Immunotherapeutic implications of negative regulation by protein tyrosine phosphatases in T cells: the emerging cases of PTP1B and TCPTP.

In the context of inflammation, T cell activation occurs by the concerted signals of the T cell receptor (TCR), co-stimulatory receptors ligation, and a pro-inflammatory cytokine microenvironment. Fine-tuning these signals is crucial to maintain T cell homeostasis and prevent self-reactivity while offering protection against infectious diseases and cancer. Recent developments in understanding the complex crosstalk between the molecular events controlling T cell activation and the balancing regulatory cues offer novel approaches for the development of T cell-based immunotherapies. Among the complex regulatory processes, the balance between protein tyrosine kinases (PTK) and the protein tyrosine phosphatases (PTPs) controls the transcriptional and metabolic programs that determine T cell function, fate decision, and activation. In those, PTPs are de facto regulators of signaling in T cells acting for the most part as negative regulators of the canonical TCR pathway, costimulatory molecules such as CD28, and cytokine signaling. In this review, we examine the function of two close PTP homologs, PTP1B (PTPN1) and T-cell PTP (TCPTP; PTPN2), which have been recently identified as promising candidates for novel T-cell immunotherapeutic approaches. Herein, we focus on recent studies that examine the known contributions of these PTPs to T-cell development, homeostasis, and T-cell-mediated immunity. Additionally, we describe the signaling networks that underscored the ability of TCPTP and PTP1B, either individually and notably in combination, to attenuate TCR and JAK/STAT signals affecting T cell responses. Thus, we anticipate that uncovering the role of these two PTPs in T-cell biology may lead to new treatment strategies in the field of cancer immunotherapy. This review concludes by exploring the impacts and risks that pharmacological inhibition of these PTP enzymes offers as a therapeutic approach in T-cell-based immunotherapies.

The induction of SHP-1 degradation by TAOK3 ensures the responsiveness of T cells to TCR stimulation.

Thousand-and-one-amino acid kinase 3 (TAOK3) is a serine and threonine kinase that belongs to the STE-20 family of kinases. Its absence reduces T cell receptor (TCR) signaling and increases the interaction of the tyrosine phosphatase SHP-1, a major negative regulator of proximal TCR signaling, with the kinase LCK, a component of the core TCR signaling complex. Here, we used mouse models and human cell lines to investigate the mechanism by which TAOK3 limits the interaction of SHP-1 with LCK. The loss of TAOK3 decreased the survival of naïve CD4+ T cells by dampening the transmission of tonic and ligand-dependent TCR signaling. In mouse T cells, Taok3 promoted the secretion of interleukin-2 (IL-2) in response to TCR activation in a manner that depended on Taok3 gene dosage and on Taok3 kinase activity. TCR desensitization in Taok3-/- T cells was caused by an increased abundance of Shp-1, and pharmacological inhibition of Shp-1 rescued the activation potential of these T cells. TAOK3 phosphorylated threonine-394 in the phosphatase domain of SHP-1, which promoted its ubiquitylation and proteasomal degradation. The loss of TAOK3 had no effect on the abundance of SHP-2, which lacks a residue corresponding to SHP-1 threonine-394. Modulation of SHP-1 abundance by TAOK3 thus serves as a rheostat for TCR signaling and determines the activation threshold of T lymphocytes.

Loss of T-cell protein tyrosine phosphatase in the intestinal epithelium promotes local inflammation by increasing colonic stem cell proliferation.

T-cell protein tyrosine phosphatase (TC-PTP) has a critical role in the development of the immune system and has been identified as a negative regulator of inflammation. Single-nucleotide polymorphisms in the TC-PTP locus have been associated with increased susceptibility to inflammatory bowel diseases (IBDs) in patients. To further understand how TC-PTP is related to IBDs, we investigated the role of TC-PTP in maintaining the intestinal epithelial barrier using an in vivo genetic approach. Intestinal epithelial cell (IEC)-specific deletion of TC-PTP was achieved in a mouse model at steady state and in the context of dextran sulphate sodium (DSS)-induced colitis. Knockout (KO) of TC-PTP in IECs did not result in an altered intestinal barrier. However, upon DSS treatment, IEC-specific TC-PTP KO mice displayed a more severe colitis phenotype with a corresponding increase in the immune response and inflammatory cytokine profile. The absence of TC-PTP caused an altered turnover of IECs, which is further explained by the role of the tyrosine phosphatase in colonic stem cell (CoSC) proliferation. Our results suggest a novel role for TC-PTP in regulating the homeostasis of CoSC proliferation. This supports the protective function of TC-PTP against IBDs, independently of its previously demonstrated role in intestinal immunity.

Mining the Complex Family of Protein Tyrosine Phosphatases for Checkpoint Regulators in Immunity.

The family of protein tyrosine phosphatases (PTPs) includes 107 genes in humans that are diverse in their structures and expression profiles. The majority are present in immune cells and play various roles in either inhibiting or promoting the duration and amplitude of signaling cascades. Several PTPs, including TC-PTP (PTPN2) and SHP-1 (PTPN6), have been recognized as being crucial for maintaining proper immune response and self-tolerance, and have gained recognition as true immune system checkpoint modulators. This chapter details the most recent literature on PTPs and immunity by examining their known functions in regulating signaling from either established checkpoint inhibitors or by their intrinsic properties, as modulators of the immune response. Notably, we review PTP regulatory properties in macrophages, antigen-presenting dendritic cells, and T cells. Overall, we present the PTP gene family as a remarkable source of novel checkpoint inhibitors wherein lies a great number of new targets for immunotherapies.

SLAMF7 is critical for phagocytosis of haematopoietic tumour cells via Mac-1 integrin.

Cancer cells elude anti-tumour immunity through multiple mechanisms, including upregulated expression of ligands for inhibitory immune checkpoint receptors. Phagocytosis by macrophages plays a critical role in cancer control. Therapeutic blockade of signal regulatory protein (SIRP)-α, an inhibitory receptor on macrophages, or of its ligand CD47 expressed on tumour cells, improves tumour cell elimination in vitro and in vivo, suggesting that blockade of the SIRPα-CD47 checkpoint could be useful in treating human cancer. However, the pro-phagocytic receptor(s) responsible for tumour cell phagocytosis is(are) largely unknown. Here we find that macrophages are much more efficient at phagocytosis of haematopoietic tumour cells, compared with non-haematopoietic tumour cells, in response to SIRPα-CD47 blockade. Using a mouse lacking the signalling lymphocytic activation molecule (SLAM) family of homotypic haematopoietic cell-specific receptors, we determined that phagocytosis of haematopoietic tumour cells during SIRPα-CD47 blockade was strictly dependent on SLAM family receptors in vitro and in vivo. In both mouse and human cells, this function required a single SLAM family member, SLAMF7 (also known as CRACC, CS1, CD319), expressed on macrophages and tumour cell targets. In contrast to most SLAM receptor functions, SLAMF7-mediated phagocytosis was independent of signalling lymphocyte activation molecule-associated protein (SAP) adaptors. Instead, it depended on the ability of SLAMF7 to interact with integrin Mac-1 (refs 18, 19, 20) and utilize signals involving immunoreceptor tyrosine-based activation motifs. These findings elucidate the mechanism by which macrophages engulf and destroy haematopoietic tumour cells. They also reveal a novel SAP adaptor-independent function for a SLAM receptor. Lastly, they suggest that patients with tumours expressing SLAMF7 are more likely to respond to SIRPα-CD47 blockade therapy.

An evaluation by potential IVF/Donor Oocyte patients of the Use and Handling of the Bemfola® Pen compared with the Gonal-f® Pen and Puregon Pen® / Evaluación del uso y manejo de la pluma Bemfola® en comparación con el de la pluma Gonal-f® y la pluma Puregon® en pacientes potenciales de FIV/ donantes de ovocitos

BACKGROUND: Since the 1990s recombinant human FSH (r-hFSH), such as Gonal-f® and Puregon®, have been in widespread use for fertility treatment [1]. More recently Bemfola®, biosimilar to r-hFSH, has been introduced with similar efficacy and safety to Gonal-f® [2], but delivered in a novel, innovative injector pen system (Reddot design award 2011). The Bemfola® pen (BP) is a single-use, disposable pen available in five different presentations (i.e., 75IU, 150IU, 225IU, 300IU and 450IU), each of which provides a range of doses that it can deliver. Non-compliance to hormonal treatment regimens might be a critical issue to reach therapeutic goals. The use of pens by patients is often limited by factors such as fear of injection, but can be also related to the device itself [3-6]. Therefore, easy-to-use devices may also positively influence physicians» hormonal prescribing habits and patient's compliance. Accordingly, this user acceptance study aimed to assess the use of the Bemfola® pen in a population of potential users with regard to the easiness and convenience of handling of the Bemfola® Pen in comparison to the Gonal-f® pen and Puregon® pen. Material and Methods Randomised and single-blind study with three-arm user test. The investigation was conducted in females who considered undergoing hormonal treatment for the first time (naïve) and who were considering to start an IVF or donor egg treatment cycle. A total of 10 centers from Spain participated in this investigation. This study of user acceptance included 460 females qualifying for potential patients considering a therapy with follicle stimulating hormone. Users received the three pens in a randomized, consecutive sequence, completed for each of the pen one questionnaire (same for all 3 pens) and thereafter completed a concluding questionnaire comparing the handling, convenience and indicating their preference among the 3 pens. No self-injections were performed and an application pad for injections was used. Results The Bemfola® pen showed the highest scorings and strong preferences in all pen features assessed and achieved the highest proportion of best choice compared to both the Gonal-f® and Puregon®. pen. Conclusions The results indicated significant preferences of women, who intended to undergo a hormonal treatment, for the Bemfola® pen compared to both the Puregon® pen and the Gonal-f® pen

ANTECEDENTES: Desde la década de los noventa, la hormona foliculoestimulante humana recombinante (hFSH-r) como Gonal-f® y Puregon®, se ha utilizado ampliamente en el tratamiento de la fertilidad [1]. Más recientemente se ha introducido Bemfola®, biosimilar de la hFSH-r con eficacia y seguridad similar a Gonal-f® [2], pero desarrollada con un innovador sistema de pluma inyectora (premio de diseño Reddot, 2011). Bemfola® es una pluma precargada desechable de un solo uso, disponible en cinco presentaciones diferentes (75 UI, 150 UI, 225 UI, 300 UI y 450 UI), cada una de las cuales proporciona un rango de dosis determinado. El no-cumplimiento de las pautas de tratamiento hormonal es un problema fundamental en la consecución de los objetivos terapéuticos. El uso de plumas por las pacientes se ve a menudo limitado por el miedo a la inyección e incluso relacionado con el propio dispositivo [3-6]. Por tanto, los dispositivos de fácil uso pueden influir positivamente tanto en los hábitos de prescripción de terapias hormonales de los médicos como en el cumplimiento del paciente. En consecuencia, el objetivo de este estudio consiste en evaluar el uso de Bemfola® en una población de usuarias potenciales con respecto a la facilidad, y conveniencia en su manejo en comparación con las plumas Gonal-f® y Puregon®. Material y Métodos Estudio aleatorizado y simple ciego de tres ramas de tratamiento. Esta investigación se llevó a cabo en mujeres sin tratamiento previo que estaban considerando bien iniciar un ciclo de FIV o bien ser donantes de ovocitos. En este estudio participaron 10 centros de fertilidad de España. Se incluyeron 460 mujeres cualificadas para ser «pacientes potenciales de terapia hormonal con hormona foliculoestimulante humana recombinante» Las usuarias recibieron las tres plumas (Bemfola®, Gonal-f® y Puregon®) en una secuencia aleatoria y consecutiva, y completaron un cuestionario idéntico por cada una de las plumas, y un cuestionario de conclusión con el fin de comparar el manejo, la comodidad y la preferencia de las tres plumas. En ningún caso se realizaron auto-inyecciones y en su lugar se utilizó una almohadilla de aplicación de inyecciones. Resultados La pluma Bemfola® mostró la mayor puntuación y elevadas preferencias en todas las características evaluadas, y alcanzó la mayor proporción de «mejor» opción en comparación con la pluma Gonal-f® y la pluma Puregon®. Conclusiones Los resultados mostraron preferencias significativas de mujeres que tenían la intención de someterse a un tratamiento hormonal, para la pluma Bemfola® en comparación con las plumas Gonal-f® y Puregon®

Evaluación del uso y manejo de la pluma Bemfola® en comparación con el de la pluma Gonal-f® y la pluma Puregon® en pacientes potenciales de FIV/ donantes de ovocitos / An evaluation by potential IVF/Donor Oocyte patients of the Use and Handling of the Bemfola® Pen compared with the Gonal-f® Pen and Puregon Pen®

ANTECEDENTES: Desde la década de los noventa, la hormona foliculoestimulante humana recombinante (hFSH-r) como Gonal-f® y Puregon®, se ha utilizado ampliamente en el tratamiento de la fertilidad [1]. Más recientemente se ha introducido Bemfola®, biosimilar de la hFSH-r con eficacia y seguridad similar a Gonal-f® [2], pero desarrollada con un innovador sistema de pluma inyectora (premio de diseño Reddot, 2011). Bemfola® es una pluma precargada desechable de un solo uso, disponible en cinco presentaciones diferentes (75 UI, 150 UI, 225 UI, 300 UI y 450 UI), cada una de las cuales proporciona un rango de dosis determinado. El no-cumplimiento de las pautas de tratamiento hormonal es un problema fundamental en la consecución de los objetivos terapéuticos. El uso de plumas por las pacientes se ve a menudo limitado por el miedo a la inyección e incluso relacionado con el propio dispositivo [3-6]. Por tanto, los dispositivos de fácil uso pueden influir positivamente tanto en los hábitos de prescripción de terapias hormonales de los médicos como en el cumplimiento del paciente. En consecuencia, el objetivo de este estudio consiste en evaluar el uso de Bemfola® en una población de usuarias potenciales con respecto a la facilidad, y conveniencia en su manejo en comparación con las plumas Gonal-f® y Puregon®. Material y MÉTODOS: Estudio aleatorizado y simple ciego de tres ramas de tratamiento. Esta investigación se llevó a cabo en mujeres sin tratamiento previo que estaban considerando bien iniciar un ciclo de FIV o bien ser donantes de ovocitos. En este estudio participaron 10 centros de fertilidad de España. Se incluyeron 460 mujeres cualificadas para ser «pacientes potenciales de terapia hormonal con hormona foliculoestimulante humana recombinante». Las usuarias recibieron las tres plumas (Bemfola®, Gonal-f® y Puregon®) en una secuencia aleatoria y consecutiva, y completaron un cuestionario idéntico por cada una de las plumas, y un cuestionario de conclusión con el fin de comparar el manejo, la comodidad y la preferencia de las tres plumas. En ningún caso se realizaron auto-inyecciones y en su lugar se utilizó una almohadilla de aplicación de inyecciones. RESULTADOS: La pluma Bemfola® mostró la mayor puntuación y elevadas preferencias en todas las características evaluadas, y alcanzó la mayor proporción de «mejor» opción en comparación con la pluma Gonal-f® y la pluma Puregon®. CONCLUSIONES: Los resultados mostraron preferencias significativas de mujeres que tenían la intención de someterse a un tratamiento hormonal, para la pluma Bemfola® en comparación con las plumas Gonal-f® y Puregon®

BACKGROUND: Since the 1990s recombinant human FSH (r-hFSH), such as Gonal-f® and Puregon®, have been in widespread use for fertility treatment [1]. More recently Bemfola® has been introduced with familiar efficacy and safety to Gonal-f® [2], but delivered in a novel, innovative injector pen system (Reddot design award 2011). The Bemfola® pen (BP) is a singleuse, disposable pen available in five different presentations (i.e., 75IU, 150IU, 225IU, 300IU and 450IU), each of which provides a range of doses that it can deliver. Non-compliance to hormonal treatment regimens might be a critical issue to reach therapeutic goals. The use of pens by patients is often limited by factors such as fear of injection, but can be also related to the device itself [3-6]. Therefore, easy-to-use devices may also positively influence physicians' hormonal prescribing habits and patient's compliance. Accordingly, this user acceptance study aimed to assess the use of the Bemfola® pen in a population of potential users with regard to the easiness and convenience of handling of the Bemfola® Pen in comparison to the Gonal-f® pen and Puregon® pen. Material and methods Randomised and single-blind study with three-arm user test. The investigation was conducted in females who considered undergoing hormonal treatment for the first time (naïve) and who were considering to start an IVF or donor egg treatment cycle. A total of two 10 centres from Spain participated in this investigation. This study of user acceptance included 460 females qualifying for potential patients considering a therapy with follicle stimulating hormone. Users received the three pens in a randomized, consecutive sequence, complete for each of the pen one questionnaire (same for all 3 pens) and thereafter complete a concluding questionnaire comparing the handling, convenience and indicating their preference among the 3 pens. No self-injections were performed and an application pad for injections was used. Results The Bemfola® pen showed the highest scorings and strong preferences in all pen features assessed and achieved the highest proportion of best choice compared to both, the Gonal-f® and Puregon® pen. Conclusions The results indicated significant preferences of women, who intended to undergo a hormonal treatment, for the Bemfola® pen compared to both the Puregon® pen and the Gonal-f® pen

A hematopoietic cell-driven mechanism involving SLAMF6 receptor, SAP adaptors and SHP-1 phosphatase regulates NK cell education.

Activation of natural killer (NK) cells by hematopoietic target cells is controlled by the SLAM family of receptors and by the associated SAP family of adaptors. Here we found that SLAM receptors also enhanced NK cell activation by nonhematopoietic target cells, which lack ligands for SLAM receptors. This function was mediated by SLAMF6, a homotypic SLAM receptor found on NK cells and other hematopoietic cells, and was regulated by SAP adaptors, which uncoupled SLAM receptors from phosphatase SHP-1 and diminished the effect of SLAMF6 on NK cell responsiveness toward nonhematopoietic cells. Thus, in addition to their role in NK cell activation by hematopoietic cells, the SLAM-SAP pathways influence responsiveness toward nonhematopoietic targets by a process akin to NK cell 'education'.

Modulating p56Lck in T-Cells by a Chimeric Peptide Comprising Two Functionally Different Motifs of Tip from Herpesvirus saimiri.

The Lck interacting protein Tip of Herpesvirus saimiri is responsible for T-cell transformation both in vitro and in vivo. Here we designed the chimeric peptide hTip-CSKH, comprising the Lck specific interacting motif CSKH of Tip and its hydrophobic transmembrane sequence (hTip), the latter as a vector targeting lipid rafts. We found that hTip-CSKH can induce a fivefold increase in proliferation of human and Aotus sp. T-cells. Costimulation with PMA did not enhance this proliferation rate, suggesting that hTip-CSKH is sufficient and independent of further PKC stimulation. We also found that human Lck phosphorylation was increased earlier after stimulation when T-cells were incubated previously with hTip-CSKH, supporting a strong signalling and proliferative effect of the chimeric peptide. Additionally, Lck downstream signalling was evident with hTip-CSKH but not with control peptides. Importantly, hTip-CSKH could be identified in heavy lipid rafts membrane fractions, a compartment where important T-cell signalling molecules (LAT, Ras, and Lck) are present during T-cell activation. Interestingly, hTip-CSKH was inhibitory to Jurkat cells, in total agreement with the different signalling pathways and activation requirements of this leukemic cell line. These results provide the basis for the development of new compounds capable of modulating therapeutic targets present in lipid rafts.

EAT-2, a SAP-like adaptor, controls NK cell activation through phospholipase Cγ, Ca++, and Erk, leading to granule polarization.

Ewing's sarcoma-associated transcript 2 (EAT-2) is an Src homology 2 domain-containing intracellular adaptor related to signaling lymphocytic activation molecule (SLAM)-associated protein (SAP), the X-linked lymphoproliferative gene product. Both EAT-2 and SAP are expressed in natural killer (NK) cells, and their combined expression is essential for NK cells to kill abnormal hematopoietic cells. SAP mediates this function by coupling SLAM family receptors to the protein tyrosine kinase Fyn and the exchange factor Vav, thereby promoting conjugate formation between NK cells and target cells. We used a variety of genetic, biochemical, and imaging approaches to define the molecular and cellular mechanisms by which EAT-2 controls NK cell activation. We found that EAT-2 mediates its effects in NK cells by linking SLAM family receptors to phospholipase Cγ, calcium fluxes, and Erk kinase. These signals are triggered by one or two tyrosines located in the carboxyl-terminal tail of EAT-2 but not found in SAP. Unlike SAP, EAT-2 does not enhance conjugate formation. Rather, it accelerates polarization and exocytosis of cytotoxic granules toward hematopoietic target cells. Hence, EAT-2 promotes NK cell activation by molecular and cellular mechanisms distinct from those of SAP. These findings explain the cooperative and essential function of these two adaptors in NK cell activation.

X-linked lymphoproliferative syndromes and related autosomal recessive disorders.

PURPOSE OF REVIEW: X-linked lymphoproliferative (XLP) syndromes and related autosomal disorders are severe primary immune deficiencies triggered by infection with Epstein-Barr virus (EBV), the causative agent of infectious mononucleosis. Recent findings reviewed herein provided key new insights into the genetic and immunological basis of these diseases. They also improved our comprehension of the immunological mechanisms controlling EBV infection. RECENT FINDINGS: Mutations of an X-linked gene, SH2D1A, which encodes the signaling lymphocytic activation molecule (SLAM)-associated protein (SAP), are responsible for most cases of XLP disorders. More recently, other genetic causes for XLP syndromes and autosomal recessive variants of this disease were elucidated. Mutations in genes such as XIAP, ITK, and CD27 were identified. The clinical manifestations and immunological defects seen in these patients were characterized. SUMMARY: The similarities and differences in immunological defects and clinical manifestations between XLP syndromes and related autosomal recessive disorders enabled important new insights into the pathogenesis of these diseases. They also helped our comprehension of the mechanisms implicated in the control of EBV infection. They suggested that CD8+ T cells, natural killer (NK) cells, and NKT cells are critically involved.

The adaptor SAP controls NK cell activation by regulating the enzymes Vav-1 and SHIP-1 and by enhancing conjugates with target cells.

The adaptor SAP, mutated in X-linked lymphoproliferative disease, has critical roles in multiple immune cell types. Among these, SAP is essential for the ability of natural killer (NK) cells to eliminate abnormal hematopoietic cells. Herein, we elucidated the molecular and cellular bases of this activity. SAP enhanced NK cell responsiveness by a dual molecular mechanism. It coupled SLAM family receptors to the kinase Fyn, which triggered the exchange factor Vav-1 and augmented NK cell activation. SAP also prevented the inhibitory function of SLAM family receptors. This effect was Fyn independent and correlated with uncoupling of SLAM family receptors from the lipid phosphatase SHIP-1. Both mechanisms cooperated to enable conjugate formation with target cells and to stimulate cytotoxicity and cytokine secretion by NK cells. These data showed that SAP secures NK cell activation by a dichotomous molecular mechanism, which is required for conjugate formation. These findings may have implications for the role of SAP in other immune cell types.

Importance and mechanism of 'switch' function of SAP family adapters.

The signaling lymphocytic activation molecule (SLAM)-associated protein (SAP) family of adapters includes SAP, Ewing's sarcoma-associated transcript-2 (EAT-2), and EAT-2-related transducer (ERT). These Src homology-2 (SH2) domain-only molecules play critical roles in immune regulation. The prototype of the SAP family, SAP, is mutated in X-linked lymphoproliferative disease in humans. Moreover, genetically engineered mice lacking one or more SAP family members have defects in multiple immune cell types including T cells, natural killer (NK) cells, NKT cells, and B cells. Accumulating data show that SAP family adapters regulate immunity by influencing the functions of SLAM family receptors, through two distinct but cooperative mechanisms. First, SAP family adapters couple SLAM family receptors to active biochemical signals, which promote immune cell functions. Second, SAP family adapters interfere with the intrinsic ability of SLAM family receptors to trigger inhibitory signals, which could be mediated via molecules such as SH2 domain-containing 5'-inositol phosphatase-1. The latter effect of SAP family adapters does not seem to be because of direct blocking of inhibitory effector binding to SLAM family receptors. Rather, it appears to implicate alternative mechanisms such as functional competition, trans-regulation, or steric hindrance. In the absence of SAP family adapters, the inhibitory signals mediated by SLAM family receptors suppress critical activating receptors, explaining in part the pronounced phenotypes seen in SAP family adapter-deficient humans and mice. Thus, SAP family adapters are molecular switches that regulate immunity as a result of their capacity to control the type of signals and functions emanating from SLAM family receptors.

Evaluación biológica de dos sistemas de apareamiento en ovinos de raza Columbia en producción intensiva / Biological evaluation of two breeding systems of intensive production in the Columbia breed sheep

The biological efficiency of two breeding systems for sheep in the Mexican high plateau was evaluated. A total of 300 adult and 60 replacement sheep of the Columbia breed were randomly distributed into two groups of 150 adults and 30 young ones (mean age to first birth of 18 months). Mates of 36 days with natural mount every eight months (March, November and July) were done in the first group (intensive system). In the second group (annual system), a 45-day mating was done starting on November every year. Marker males were introduced 15 days before mating in all cases, which were replaced on the first day of mating for stallions at a one male for every 20 female ratios. The physical condition of all females was evaluated every month. The animals grazed 8 to 9 hours in grasslands of alfalfa (Medicago sativa) and Orchard (Dactylis glomerata) and Rye (Lolium perenne) grasses irrigated by aspersion. Only the sheep in the intensive system received supplement during lactation and re-mating. Breeding was achieved in both systems in all seasons. The mean fertility of the three breeding of the intensive system was 83.9%; while the mean fertility of the two annual breeding was 88.3% (P < 0.05). Prolificacy was 1.12 vs 1.32 (P < 0.05) for the intensive and annual breeding, respectively; mortality at weaning was 5.3% vs 6.4% (P < 0.05), weaning rate was 0.89 vs 1.09 (P < 0.05), the number of weaned lambs per ewe in two years was 2.5 vs 2.0 and lamb weight was 55.9 vs 44.4 kg (P < 0.05), respectively. Adult ewes were superior to the young ones in all the evaluated parameters, regardless of the kind of mating (P < 0.05). Results in this study allowed to compare the biological efficiency between an intensive breeding system every eight months and an annual breeding system. They also show the possibility of mating sheep of the Columbia breed in an intensive way.

Se evaluó la eficacia biológica de dos sistemas de apareamiento en ovinos del altiplano central de México. Un total de 300 ovejas adultas y 60 de reemplazo de la raza Columbia se distribuyeron al azar en dos grupos de 150 adultas y 30 jóvenes (edad promedio al primer parto de 18 meses). En el primer grupo (sistema intensivo) se realizaron empadres de 36 días, con monta natural cada ocho meses (marzo, noviembre y julio), mientras que en el segundo grupo (sistema anual) se llevó a cabo un empadre de 45 días, iniciando en noviembre de cada año. En todos los casos, quince días antes del empadre se introdujeron machos marcadores, que en la fecha de inicio del empadre se sustituían por sementales en proporción de un macho por cada 20 hembras. Mensualmente se evaluó la condición física de todas las hembras. Los animales pastorearon de ocho a nueve horas diarias en praderas de alfalfa (Medicago sativa) y pastos orchard (Dactylis glomerata) y rye grass (Lolium perenne) irrigadas por aspersión. Solamente las ovejas del sistema intensivo recibieron complemento durante la lactancia y el reempadre. En los dos sistemas se lograron apareamientos en todas las épocas, la fertilidad en los tres empadres del sistema intensivo fue de 83.9%, mientras que el promedio de los dos empadres anuales fue de 88.3% (P < 0.05). En el mismo orden, la prolificidad fue de 1.12 vs 1.32 (P < 0.05); la mortalidad al destete, 5.3% vs 6.4% (P > 0.05); la tasa de destete, 0.89 vs 1.09 (P < 0.05); el número de corderos destetados por oveja en dos años fue de 2.5 vs 2.0, y de kg de cordero de 55.9 vs 44.4 kg (P < 0.05). Independientemente del tipo de empadre, las ovejas adultas fueron superiores a las jóvenes en todos los parámetros evaluados (P < 0.05). Los resultados de este estudio permiten comparar la eficacia biológica entre un sistema de apareamiento intensivo cada ocho meses y uno anual, también muestra la posibilidad de aparear ovejas de la raza Columbia en forma intensiva.

El efecto macho como inductor de la actividad reproductiva en sistemas intensivos de apareamiento en ovinos / Use of the male effect to induce reproductive activity in ovine intensive breeding systems

The presence of the male effect and its importance in the reproductive management of Columbia ewes was evaluated during a comparative study between a herd of ewes subjected to an annual breeding system with services in November (AS) and another herd subjected to an intensive system with breeding periods in November, July and March (IS). The two herds were kept on intensive irrigated prairies with moderate climate: the ewes in the IS were supplemented during the lactation and rebreeding periods. Estrus expression was detected by the presence of marks on the rump left by aniline-impregnated teaser males. In addition, the concentrations of progesterone were determined in blood samples from 20 adult ewes and 5 ewe-lambs from each breeding system. These samples were taken twice per week from the time the teaser males were introduced. The conception date for each ewe was retrospectively calculated from the date of lambing. The results indicate a clear male effect in the IS group during the breeding periods of July and March, when such a male effect proved to be very important for the reproductive success of the herd. In contrast, the male effect was not apparent during November breeding periods because the animals of both herds were already cycling when the teaser males were introduced at that time of the year. It is concluded that the use of the male effect can improve the reproductive efficiency of Columbia ewes exposed to intensive breeding systems in Mexico.

Se determinó la presencia del efecto macho y su importancia en el manejo reproductivo de ovejas de la raza Columbia, en un estudio comparativo entre un rebaño sometido a un sistema de apareamiento anual con empadres en noviembre (S-A) y otro intensivo con empadres en noviembre, julio y marzo (S-I). Los rebaños se mantuvieron en condiciones de pastoreo intensivo en praderas irrigadas de clima templado: las ovejas en el S-I se complementaron durante la lactancia y el reempadre. Se estableció la ocurrencia de estros por medio de la presencia de marcas de anilina que los machos vasectomizados dejaron en la grupa. Además, en cada sistema de empadre se determinaron las concentraciones de progesterona en muestras sanguíneas de 20 ovejas adultas y cinco primalas dos veces por semana a partir de la introducción de los machos. La distribución de los partos permitió calcular la fecha de concepción. Los resultados indican un claro efecto macho en el grupo S-I durante los empadres de julio y marzo, cuando dicho efecto macho confirmó su importancia en el éxito reproductivo del rebaño.. En cambio, el efecto macho no se presentó durante el empadre de noviembre del grupo S-I, ni durante los empadres del grupo S-A, debido a que al inicio de dichos empadres las ovejas se encontraban ciclando. Se concluye que el efecto macho puede ser utilizado para mejorar la eficiencia reproductiva de ovejas de la raza Columbia sometidas a sistemas intensivos de apareamiento en México.

Efecto de los implantes subcutáneos de melatonina y la suplementación alimentaria, sobre la inducción de la actividad ovárica en ovejas pelibuey durante la época de anestro / Effect of melatonin subcutaneous implants and feed supplementation on ovarian activity induction in Pelibuey ewes during the anestrous season

Se evaluó el efecto de implantes de melatonina sobre la inducción de la actividad ovárica en ovejas Pelibuey suplementadas o no durante la época de anestro. El estudio se realizó bajo condiciones de trópico húmedo (20º 4' latitud Norte). Se utilizaron 90 ovejas Pelibuey en anestro que parieron a finales del otoño (noviembre y diciembre). La mitad del rebaño se suplementó de febrero a junio con concentrado (14 por ciento PC y 3500 Kcal/kg). A mediados de marzo, los grupos suplementados y no suplementados fueron subdivididos para recibir o no un implante subcutáneo conteniendo 18 mg de melatonina, de esta manera se formaron los siguientes grupos: M + S (suplementado, con melatonina; n = 24), M + P (pastoreo con melatonina; n = 23); S (suplementado; n = 22) y testigo (en pastoreo; n = 21). La actividad ovárica en las ovejas fue seguida por determinación de niveles de progesterona plasmática y por detección diaria de estros. Sólo 54.4 por ciento del rebaño presentó estro. No se encontraron diferencias (P > 0.05) entre tratamientos en los porcentajes de ovejas que ovularon (M + S = 84.6 por ciento; M + P = 72.9 por ciento; S = 80.0 por ciento y testigo = 55.5 por ciento) y que mostraron estro (M + S = 70.8 por ciento; M + P = 47.8 por ciento; S = 45.4 por ciento y testigo = 52.3 por ciento), ni en el intervalo del inicio del tratamiento con melatonina a primera elevación de progesterona (11.6 ñ 2.9 días; 16.5 ñ 3.3 días; 12.2 ñ 1.3 días y 8.0 ñ 3.6 días para los grupos M + S, M + P, S y testigo, respectivamente). El intervalo inicio del tratamiento con melatonina-primer estro (M + S, 18.8 ñ 2.8 días; M + P, 14.0 ñ 1.9 días; S, 10.4 ñ 1.5 días; testigo, 11.5 ñ 1.9 días) también fue igual (P > 0.05) entre grupos. Se concluye que la rápida inducción de la actividad ovárica de las ovejas en anestro no fue debida a la melatonina exógena o a la suplementación con concentrado, sino a un posible "efecto macho".

Desarrollo de un método de radioinmunoanálisis para cortisol, utilizando anticuerpos obtenidos y purificados de la yema de huevo de gallinas inmunizadas / A radioimmunoassay method developed with antibodies purified from the yolk of immunized hen eggs

Se indujeron anticuerpos anticortisol en gallinas de postura, para lo cual se realizó una primera aplicación de 1 mg de cortisol conjugado con albúmina sérica bovina (BSA) y mezclado con adyuvante completo de Freund y solución salina fisiológica; posteriormente se realizaron seis aplicaciones más de 0.5 mg del mismo inmunógeno, los cuales se aplicaron a intervalos de 15 días. Se encontró en suero un título promedio, durante el periodo de colección del huevo, de 39.4 por ciento en una dilución de trabajo 1:1000. Los anticuerpos anticortisol se recuperaron y purificaron a partir de la yema de huevo y con ellos se desarrolló la pueba de radioinmunoanálisis (RIA) de fase líquida. Los anticuerpos de la yema mostraron alta especificidad para el cortisol respecto de otros esteroides (reacción cruzada menora 0.1 por ciento con androstenediona, estradiol, 17-hidroxiprogesterona y testosterona), así como una sensibilidad de 339 pg/ml. La precisión del RIA fue adecuada (C.V intensayo menor a 15 por ciento), al igual que la recuperación del sistema. El rendimiento fue de 594 552.63 mg de proteína que sirven para procesar 95 000 000 tubos. Se concluye que la yema de huevo de gallinas inmunizadas es una efectiva fuente de anticuerpos anticortisol, la cual puede ser utilizada como una alternativa al suero de conejos

Influencia del carnero sobre la ocurrencia de estros en la oveja Pelibuey / Ram effect on oestrus activity in Pelibuey ewes

Con el objetivo de evaluar el efecto de la introducción repentina del carnero sobre la ocurrencia de estros en un rebaño de ovejas Pelibuey del trópico húmedo de México, se analizó la información de registros del empadre de verano en 328 ovejas Pelibuey (62 corderas y 266 adultas) en el Centro de Enseñanza, Investigación y Extensión en Ganadería Tropical, de la Facultad de Medicina Veterinaria y Zooctenia de la Universidad Nacional Autónoma de México (20º 04' latitud Norte y 97º 03' longitud Oeste). Dentro del programa reproductivo del rebaño se realizan cada ocho meses empadres con monta dirigida, previa detección de estros en las ovejas con el uso de carneros vasectomizados. Durante el periodo que transcurre entre un empadre y otro, los machos son separados totalmente del rebaño y se les confina durante todo el año en potreros aislados, excepto los 35 días que dura cada empadre. Después de iniciado el periodo de montas, los máximos porcentajes diarios de ovejas mostrando estro se observaron en los días 17 (7.4 por ciento) y 23 (14.2 por ciento), con un 70 por ciento de los estros en el rebaño ocurriendo dentro de un periodo comprendido entre los días 15 y 24 del empadre, lo cual concuerda con el patrón de distribución de estros informado para el "efecto macho". Asimismo un alto porcentaje (90.5 por cinto) de las hembras que entraron al empadre exhibieron estro, con una frecuencia casi nula de ovejas que repitieron un segundo celo (1.0 por ciento) durante el periodo de empadre a pesar de que muchas de ellas no quedaron gestantes en el primer servicio. Se concluye que la introducción repentina de los carneros al rebaño al inicio del periodo de montas influyó sobre la actividad ovárica de las ovejas Pelibuey en el trópico húmedo mexicano