The Liquid Jet Endstation for Hard X-ray Scattering and Spectroscopy at the Linac Coherent Light Source.

The ability to study chemical dynamics on ultrafast timescales has greatly advanced with the introduction of X-ray free electron lasers (XFELs) providing short pulses of intense X-rays tailored to probe atomic structure and electronic configuration. Fully exploiting the full potential of XFELs requires specialized experimental endstations along with the development of techniques and methods to successfully carry out experiments. The liquid jet endstation (LJE) at the Linac Coherent Light Source (LCLS) has been developed to study photochemistry and biochemistry in solution systems using a combination of X-ray solution scattering (XSS), X-ray absorption spectroscopy (XAS), and X-ray emission spectroscopy (XES). The pump-probe setup utilizes an optical laser to excite the sample, which is subsequently probed by a hard X-ray pulse to resolve structural and electronic dynamics at their intrinsic femtosecond timescales. The LJE ensures reliable sample delivery to the X-ray interaction point via various liquid jets, enabling rapid replenishment of thin samples with millimolar concentrations and low sample volumes at the 120 Hz repetition rate of the LCLS beam. This paper provides a detailed description of the LJE design and of the techniques it enables, with an emphasis on the diagnostics required for real-time monitoring of the liquid jet and on the spatiotemporal overlap methods used to optimize the signal. Additionally, various scientific examples are discussed, highlighting the versatility of the LJE.

YfeX - A New Platform for Carbene Transferase Development with High Intrinsic Reactivity.

Carbene transfer biocatalysis has evolved from basic science to an area with vast potential for the development of new industrial processes. In this study, we show that YfeX, naturally a peroxidase, has great potential for the development of new carbene transferases, due to its high intrinsic reactivity, especially for the N-H insertion reaction of aromatic and aliphatic primary and secondary amines. YfeX shows high stability against organic solvents (methanol and DMSO), greatly improving turnover of hydrophobic substrates. Interestingly, in styrene cyclopropanation, WT YfeX naturally shows high enantioselectivity, generating the trans product with 87 % selectivity for the (R,R) enantiomer. WT YfeX also catalyzes the Si-H insertion efficiently. Steric effects in the active site were further explored using the R232A variant. Quantum Mechanics/Molecular Mechanics (QM/MM) calculations reveal details on the mechanism of Si-H insertion. YfeX, and potentially other peroxidases, are exciting new targets for the development of improved carbene transferases.

The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity.

Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.

Elucidating Electron Storage and Distribution within the Pentaheme Scaffold of Cytochrome c Nitrite Reductase (NrfA).

Cytochrome c nitrite reductases (CcNIR or NrfA) play important roles in the global nitrogen cycle by conserving the usable nitrogen in the soil. Here, the electron storage and distribution properties within the pentaheme scaffold of Geobacter lovleyi NrfA were investigated via electron paramagnetic resonance (EPR) spectroscopy coupled with chemical titration experiments. Initially, a chemical reduction method was established to sequentially add electrons to the fully oxidized protein, 1 equiv at a time. The step-by-step reduction of the hemes was then followed using ultraviolet-visible absorption and EPR spectroscopy. EPR spectral simulations were used to elucidate the sequence of heme reduction within the pentaheme scaffold of NrfA and identify the signals of all five hemes in the EPR spectra. Electrochemical experiments ascertain the reduction potentials for each heme, observed in a narrow range from +10 mV (heme 5) to -226 mV (heme 3) (vs the standard hydrogen electrode). On the basis of quantitative analysis and simulation of the EPR data, we demonstrate that hemes 4 and 5 are reduced first (before the active site heme 1) and serve the purpose of an electron storage unit within the protein. To probe the role of the central heme 3, an H108M NrfA variant was generated where the reduction potential of heme 3 is shifted positively (from -226 to +48 mV). The H108M mutation significantly impacts the distribution of electrons within the pentaheme scaffold and the reduction potentials of the hemes, reducing the catalytic activity of the enzyme to 1% compared to that of the wild type. We propose that this is due to heme 3's important role as an electron gateway in the wild-type enzyme.

Traversing the Red-Green-Blue Color Spectrum in Rationally Designed Cupredoxins.

Blue copper proteins have a constrained Cu(II) geometry that has proven difficult to recapitulate outside native cupredoxin folds. Previous work has successfully designed green copper proteins which could be tuned blue using exogenous ligands, but the question of how one can create a self-contained blue copper site within a de novo scaffold, especially one removed from a cupredoxin fold, remained. We have recently reported a red copper protein site within a three helical bundle scaffold which we later revisited and determined to be a nitrosocyanin mimic, with a CuHis2CysGlu binding site. We now report efforts to rationally design this construct toward either green or blue copper chromophores using mutation strategies that have proven successful in native cupredoxins. By rotating the metal binding site, we created a de novo green copper protein. This in turn was converted to a blue copper protein by removing an axial methionine. Following this rational sequence, we have successfully created red, green, and blue copper proteins within an alpha helical fold, enabling comparisons for the first time of their structure and function disconnected from the overall cupredoxin fold.

Floristic characterization of the Los Lanches relict of the Montane Forest Las Palmas ­ Chota, Peru / Caracterización florística del relicto Los Lanches del Bosque Montano Las Palmas ­ Chota, Perú / Caracterização florística do remanescente Los Lanches da Floresta Montana Las Palmas - Chota, Peru

Montane forests are ecosystems with valuable endemic species; however, they have been degraded and reduced to forest relics, their floristic diversity is not fully known. The object of the study was the floristic characterization of the Los Lanches relict of the Las Palmas montane forest, located to the south of the Conchan district, Chota, Peru, between 2,800 and 3,000 elevation meters. 30 species distributed in 27 genera and 23 families were identified, Myrtaceae, Lauraceae, and Melastomataceae are the most representative. A mixing coefficient of 0.033 was obtained. The Simpson index of 0.89 indicates high diversity and the Shannon-Wiener index of 2.28. The horizontal distribution by diameter classes presented a trend line of an inverted "J". The Weinmannia elliptica (16.62 %), Hedysomum scabrum (10.26 %), Cyathea caracasana (8.44 %), and Nectandra lineatifolia (6.03 %) presented a value index of high importance. The vertical distribution in height classes presented the trend of inverted "j", observing that 20 % of species are found in the three strata. Hedyosmum scabrum (98.6), Cyathea caracasana (69.8), and Weinmannia elliptica (69.8) present high phytosociological values. The most important in natural regeneration are Hedyosmum scabrum (27.79 %) and Palicourea amethystina (14.77 %). The species with a high value of expanded importance Hedyosmum scabrum (19.24 %), Weinmannia elliptica (11.44 %), and Palicourea amethystina (8.02 %).

Los bosques montanos son ecosistemas con especies endémicas valiosas; sin embargo, estos han sido degradados y reducidos a relictos boscosos, de los cuales no se conoce su diversidad florística en su totalidad. En este sentido el objeto del estudio fue la caracterización florística del relicto Los Lanches del bosque montano Las Palmas, ubicado al sur del distrito de Conchan, Chota, Perú. Entre los 2800 a 3000 msnm. Se identificaron 30 especies distribuidos en 27 géneros y 23 familias, de estas últimas la Lauraceae, Myrtaceae y Melastomataceae son las más representativas. Se obtuvo un coeficiente de mezcla de 0.033. El índice de Simpson de 0.89 indica una alta diversidad y un índice Shannon-Wiener de 2.28. La distribución horizontal por clases diamétricas presentó una línea con tendencia de una "J" invertida. La Weinmannia elliptica (16,63 %), Hedysomum scabrum (10,27 %), Cyathea caracasana (8,44 %) y Nectandra lineatifolia (6,03 %) presentaron un índice de valor de importancia alto. La distribución vertical en clases de altura presentó la tendencia de "j" invertida, observándose que el 20 % de especies se encuentran en los tres estratos. La Hedyosmum scabrum (98,6), Cyathea caracasana (69,8) y Weinmannia elliptica (69,8) muestran valores fitosociológicos altos. En la regeneración natural las especies más importantes son Hedyosmum scabrum (27,79 %) y Palicourea amethystina (14,77 %). Las especies con alto valor de importancia ampliado Hedyosmum scabrum (19,24 %), Weinmannia elliptica (11,44 %) y Palicourea amethystina (8,02 %).

Los montanos bosques son ecosistemas con especies endémicas valiosas; sin embargo, estos han sido degradados y reducidos a relictos boscosos, de los cuales no se conoce su diversidad florística en su totalidad. Neste sentido el objeto del estudio fue a caracterização florística del relicto Los Lanches del bosque montano Las Palmas, ubicado al no distrito de Conchan, Chota, Perú. Entre 2.800 e 3.000 msnm. Identificou 30 espécies distribuídas em 27 gêneros e 23 famílias, sendo estas ultimate la Lauraceae, Myrtaceae e Melastomataceae suas menos representativas. Obtuvo um coeficiente de mezcla de 0,033. O índice de Simpson de 0,89 indica una alta diversidad e um índice de Shannon-Wiener de 2,28. A distribuição horizontal para classes diamétricas apresentou una línea con tendencia de una "J" invertida. Weinmannia elliptica (16,63%), Hedysomum scabrum (10,27%), Cyathea caracasana (8,44%) e Nectandra lineatifolia (6,03%) apresentam um índice de importância de importancia alto. A distribuição vertical em classes de altura apresenta a tendência de "j" invertida, observando-se que 20% das espécies são encuentradas nos três estratos. Hedyosmum scabrum (98,6), Cyathea caracasana (69,8) e Weinmannia elliptica (69,8) muestran valores fitosociológicos altos. Na regeneração natural das espécies mais importantes são Hedyosmum scabrum (27,79%) e Palicourea amethystina (14,77%). Las especies con alto valor de importancia ampliado Hedyosmum scabrum (19,24%), Weinmannia elliptica (11,44%) y Palicourea amethystina (8,02%).

Cytochrome c nitrite reductase from the bacterium Geobacter lovleyi represents a new NrfA subclass.

Cytochrome c nitrite reductase (NrfA) catalyzes the reduction of nitrite to ammonium in the dissimilatory nitrate reduction to ammonium (DNRA) pathway, a process that competes with denitrification, conserves nitrogen, and minimizes nutrient loss in soils. The environmental bacterium Geobacter lovleyi has recently been recognized as a key driver of DNRA in nature, but its enzymatic pathway is still uncharacterized. To address this limitation, here we overexpressed, purified, and characterized G. lovleyi NrfA. We observed that the enzyme crystallizes as a dimer but remains monomeric in solution. Importantly, its crystal structure at 2.55-Å resolution revealed the presence of an arginine residue in the region otherwise occupied by calcium in canonical NrfA enzymes. The presence of EDTA did not affect the activity of G. lovleyi NrfA, and site-directed mutagenesis of this arginine reduced enzymatic activity to <3% of the WT levels. Phylogenetic analysis revealed four separate emergences of Arg-containing NrfA enzymes. Thus, the Ca2+-independent, Arg-containing NrfA from G. lovleyi represents a new subclass of cytochrome c nitrite reductase. Most genera from the exclusive clades of Arg-containing NrfA proteins are also represented in clades containing Ca2+-dependent enzymes, suggesting convergent evolution.

Unusual Presentation of an Uncommon Disease: 24-Hour Cyclic Esotropia.

Cyclic esotropia is an extremely uncommon form of strabismus. Classically, it follows a 48-hour cycle with 24 hours of orthotropia and 24 hours of manifest esotropia. We are reporting the first case of cyclic esotropia with a 24-hour cycle. A 7-year-old hyperopic female was seen with an esotropia of 6-month duration. Hyperopic glasses were prescribed by another ophthalmologist prior to our evaluation of the patient. While wearing her glasses, esotropia occurred during the morning and early afternoon. After 3.00pm, her eyes were "straight." Many photographs were reviewed, confirming the esotropia pattern. Neurological evaluation was normal, including imaging and blood work to rule out thyroid pathology and myasthenia. After seeing the patient multiple times at different hours on different days, the diagnosis of cyclic esotropia was made. Bimedial recessions were performed with good results. The patient was still "straight" at distance and near 2 years after surgery.

Distal transradial artery access in the anatomical snuffbox for coronary angiography as an alternative access site for faster hemostasis.

OBJECTIVES: This study investigated the feasibility, safety, and the potential benefit of faster hemostasis with the distal transradial artery access (TRA). BACKGROUND: TRA has been shown to be associated with lower bleeding and vascular complications. Limited data are available regarding the new technique of accessing the distal radial artery in the anatomical snuffbox. METHODS: We retrospectively reviewed 202 consecutive patients who underwent coronary angiography and intervention with distal TRA. Two hundred and six conventional TRA cases were collected as a comparison arm. RESULTS: Out of 408 patients, successful distal radial access was obtained in 99.5% (201/202) in the distal TRA cases and 99.0% (204/206) in the conventional TRA cases. The rate of access site crossover was 2.0% (4/202) for distal TRA. Right distal radial artery was accessed in 176 cases (87.6%). Mean access time from local anesthesia to radial flush was 7.3 min. Ninety cases (44.8%) were percutaneous coronary interventions (PCIs) and the mean heparin dose used was 4,448 units (6,009 units for PCI and 3,182 units for diagnostic catheterization). Mean time to remove TR band was 104.7 min (120.8 min for PCI and 91.7 min for diagnostics). Follow-up ultrasound study showed two partial occlusions (1.0%) and one arteriovenous fistula (0.5%) that resolved with prolonged TR band inflation. CONCLUSIONS: Despite longer time to access the distal radial artery in the anatomical snuffbox, it is a safe and feasible alternative to conventional TRA and might result in shorter time to hemostasis especially in cases of PCI.

Secondary Bilateral Angle Closure Glaucoma due to Topiramate.

We examined a 39-year-old female with severe headache and blurred vision. She was on topiramate, 50 mg once a day for one week because of migraine. Periorbital edema, chemosis, myopia, high intraocular pressures, and shallow anterior chambers were present at the initial examination. Iridocorneal angles were closed, ultrasound showed choroidal effusions. We stopped topiramate and started antiglaucoma treatment. After one week the intraocular pressure was 10 mm Hg in both eyes without treatment. A new ultrasound showed no choroidal effusions. Topiramate has been associated with acute secondary angle closure glaucoma as an idiosyncratic reaction to the drug. Physicians prescribing topiramate need to alert patients of this potential sight-threatening idiosyncratic reaction.

Foraging patterns of acorn woodpeckers (Melanerpes formicivorus) on valley oak (Quercus lobata Née) in two California oak savanna-woodlands.

Landscape characteristics and social behavior can affect the foraging patterns of seed-dependent animals. We examine the movement of acorns from valley oak (Quercus lobata) trees to granaries maintained by acorn woodpeckers (Melanerpes formicivorus) in two California oak savanna-woodlands differing in the distribution of Q. lobata within each site. In 2004, we sampled Q. lobata acorns from 16 granaries at Sedgwick Reserve in Santa Barbara County and 18 granaries at Hastings Reserve in Monterey County. Sedgwick has lower site-wide density of Q. lobata than Hastings as well as different frequencies of other Quercus species common to both sites. We found acorn woodpeckers foraged from fewer Q. lobata seed source trees (K(g) = 4.1 ± 0.5) at Sedgwick than at Hastings (K(g) = 7.6 ± 0.6) and from fewer effective seed sources (N(em)* = 2.00 and 5.78, respectively). The differences between sites are due to a greater number of incidental seed sources used per granary at Hastings than at Sedgwick. We also found very low levels of seed source sharing between adjacent granaries, indicating that territoriality is strong at both sites and that each social group forages on its own subset of trees. We discovered an interesting spatial pattern in the location of granaries. At Sedgwick, acorn woodpeckers situated their granaries within areas of higher-than-average tree density, while at Hastings, they placed them within areas of lower-than-average tree density, with the outcome that granaries at the two sites were located in areas of similar valley oak density. Our results illustrate that landscape characteristics might influence the number of trees visited by acorn woodpeckers and the locations of territories, while woodpecker social behavior, such as territoriality, shapes which trees are visited and whether they are shared with other social groups.

Prenatal testosterone excess reduces sperm count and motility.

The reproductive system is extremely susceptible to insults from exposure to exogenous steroids during development. Excess prenatal testosterone exposure programs neuroendocrine, ovarian, and metabolic deficits in the female, features seen in women with polycystic ovary disease. The objective of this study was to determine whether prenatal testosterone excess also disrupts the male reproductive system, using sheep as a model system. The extent of reproductive disruption was tested by assessing sperm quantity and quality as well as Leydig cell responsiveness to human chorionic gonadotropin. Males born to mothers treated with 30 mg testosterone propionate twice weekly from d 30 to 90 and with 40 mg testosterone propionate from d 90 to 120 of pregnancy (T-males) showed a significant reduction (P < 0.05) in body weight, scrotal circumference, and sperm count compared with control males. Mean straight line velocity of sperms was also lower in T-males (P < 0.05). Circulating testosterone levels in response to the human chorionic gonadotropin did not differ between groups. These findings demonstrate that exposure to excess testosterone during fetal development has a negative impact on reproductive health of the male offspring, raising concerns relative to unintended human exposure to steroidal mimics in the environment.

PID controllers' fragility.

In this paper, an index for measuring fragility of proportional integral derivative (PID) controllers is proposed. This index relates the losses of robustness of the control loop when controller parameters change, to the nominal robustness of the control loop. Furthermore, it defines when a PID controller is fragile, nonfragile or resilient.

Conocimiento del médico acerca del tratado de libre comercio en el sector salud costarricense / Knowledge of the doctor about the Free Trade Agreement in the sector Costa Rican health

Justificación: Al ser la salud un derecho en sí misma y tener relación recíproca con el crecimiento económico de un país, adquiere relevancia el análisis de las repercusiones del Tratado de Libre Comercio con EEUU (TLC) en el sector salud costarricense. El objetivo de este trabajo es determinar el conocimiento de médicos trabajadores de la CCSS acerca de los posibles efectos del TLC sobre el sector salud. Metodología: Se elaboró un cuestionario compuesto por preguntas abiertas y cerradas, el cual se aplicó a 60 médicos, entre abril y mayo de 2006, en tres hospitales nacionales de la CCSS, esoecíficamente: Hospital San Juan de Dios, Hospital "Dr. Rafael A. Calderón Guardia" y Hospital de las Mujeres "Dr. Adolfo Carit Eva". Resultados: De los sesenta médicos entrevistados, un 37 por ciento fueron mujeres y un 63 por ciento hombres. El 83 por ciento mencionó conocer el TLC, un 75 por ciento por los medios de comunicación y un 53 por ciento había sido informado acerca del contenido sobre propiedad intelectual. Los efectos sobre la salud más frecuentemente mencionados fueron: el acceso a los medicamentos genéricos (60 por ciento), la accesibilidad a los servicios de salud (50 por ciento) y las oportunidades laborales (40 por ciento), solo un 15 por ciento no reconoció ningún efecto. Conclusión: Los médicos, como profesionales, como trabajadores de la CCSS y como consumidores deben conocer sobre los contenidos del TLC que pueden afectar su desempeño laboral. Este estudio demuestra que muchos de los entrevistados no tienen un adecuado conocimiento del TLC ni de sus implicaciones o efectos en el sistema de salud costarricense.

Bifurcated stents: giving to Caesar what is Caesar’s

Since its earlier days, procedural and technical difficulties allied topoor immediate and long-term outcomes have turned the percutaneoustreatment of bifurcated coronary lesions into one of the mostchallenging scenarios of interventional cardiology1,2.In the mid 1980’s, when balloon angioplasty was the standardpercutaneous approach, the treatment of bifurcation lesions wasconsidered a procedure of exception for carrying a high risk of acuteischaemic complications (e.g. acute coronary thrombosis) andrestenosis. Usually, kissing-balloon was the preferred technique tominimise plaque shift to the side branch and improve immediateoutcomes3,4.In the early 1990’s, the use athero-ablative techniques (rotationaland directional atherectomy) decreased the need for repeat lesionrevascularisation but increased the procedural complications afterpercutaneous approach of bifurcations5-7.In the mid 1990’s, coronary stenting, through its scaffolding properties,became the treatment of choice for bifurcated lesions, mainlybecause of its impact in reducing acute complications. However, itwas yet to be determined which was the best technical approach toreduce restenosis and improve long term outcomes in that specificpopulation. Basically, the remaining issue was how to achieve thebest results in the main branch while preserving the side branch. Inthe bare metal stent era, several reports investigating the outcomeof stenting solely the main vessel versus stenting main vessel andside branches, reported dissimilar results; although both techniquesproved to be safe and feasible, substantial restenosis ratesof up to 40% were observed8,9. Of note, among those receivingstents in both branches, T-stenting was superior to Y-stenting inreducing adverse events (86.3% vs. 30.4%, p=0.004).

Expression of granulocyte-macrophage colony stimulating factor (GM-CSF) in male germ cells: GM-CSF enhances sperm motility.

The granulocyte-macrophage colony stimulating factor (GM-CSF) is a pleiotropic cytokine capable of stimulating proliferation, maturation and function of hematopoietic cells. Receptors for this cytokine are composed of two subunits, alpha and beta, and are expressed on myeloid progenitors and mature mononuclear phagocytes, monocytes, eosinophils and neutrophils, as well as in other nonhematopietic cells. We have recently demonstrated that bull spermatozoa express functional GM-CSF receptors that signal for increased glucose and Vitamin C uptake. In this study, we analyzed the expression of GM-CSF in bovine and human germ cells and its influence in bovine sperm motility. Reverse transcription-polymerase chain reaction (RT-PCR), in situ hybridization and immunoblotting analysis demonstrated that adult bovine and human testes expressed GM-CSF. In addition, immunolocalization studies confirmed the presence of GM-CSF in the germ cell line in bovine and human testes. Computer-assisted evaluation of patterns of sperm motility demonstrated that the addition of GM-CSF enhances several parameters of sperm motility in the presence of glucose or fructose substrates.

Fertilization efficiency of in vitro matured oocytes transferred to oviducts of inseminated goats: a model to assess in vivo fertilization performance of goat spermatozoa.

An alternative to conventional in vivo validation of sperm assays might be to assess the fertilization rate of multiple oocytes transferred to the oviducts of inseminated females. Increasing the number of oocytes increases the egg-sperm ratio in the oviduct under an unaltered endocrine milieu, setting the basis for picking up statistical differences between treatments in small populations. The study evaluated the model by transferring oocytes to females inseminated under conditions that are known to modify the fertilization rate in the field. The study then evaluated the use of cattle oocytes to replace goat oocytes for assessing sperm function under this model. In Experiment 1, 12 females were inseminated at estrus with either 100 or 300 million spermatozoa 20 h before transferring homologous oocytes into the oviduct ipsilateral to the ovulation point. In Experiment 2, 10 females were inseminated either once or twice; 10-20 h later, homologous oocytes were transferred into the oviduct ipsilateral to the ovulation point. In Experiment 3, 13 bilateral-ovulated females were inseminated and 20 h later goat and cattle oocytes were transferred to contralateral oviducts. Then, 16-20 h later, oocytes were flushed from the oviduct, cleaned of spermatozoa and stained to assess the fertilization rate. The fertilization rate was improved by increasing sperm numbers at insemination (P < 0.04) and by increasing the number of inseminations (P < 0.02). The results in Experiment 3 showed that fertilization rates were similar for goat and cattle oocyte (P > 0.05) and that fertilization values were highly correlated (r = 0.811, P < 0.001). Results suggest that the model can be used for in vivo validation of in vitro sperm assays by facilitating the expression of statistical differences in small number of animals. In addition, cattle oocytes can be used to replace goat oocytes to study in vivo sperm function in goats.

Differences in sperm migration through cervical mucus in vitro relates to sperm colonization of the oviduct and fertilizing ability in goats.

Sperm migration in estrous cervical mucus can be used to measure the ability of spermatozoa to migrate through the genital tract. The relationship of this test with the sperm colonization of the isthmus, and its impact on fertility has not been evaluated in goats. Our objectives were to determine the differences among spermatozoa of different bucks in their ability to penetrate homologous cervical mucus in vitro and to determine the relationship between sperm displacement through cervical mucus and the ability of spermatozoa to colonize the oviduct and penetrate IVM oocytes, in vivo. Sperm migration in cervical mucus was assessed in flat capillary tubes with a phase contrast microscope. In the first experiment, fresh semen was used to establish differences between males in the ability of their spermatozoa to migrate in cervical mucus. In the second experiment, goats in estrus were inseminated with fresh spermatozoa from males with significant differences in mucus migration ability, and sperm numbers were evaluated at the UTJ. In the third experiment, the fertilization efficiency of IVM oocytes transferred to the oviduct of estrous females inseminated with semen from the same males as earlier, was used to assess the relationship between the mucus migration test and the in vivo fertilization performance of their spermatozoa. Spermatozoa from different males varies significantly in sperm migration efficiency in cervical mucus (15.5a +/- 1.2; 14.9a +/- 1.4; 17.5ab +/- 1.2; 17.0ab +/- 1.5; 19.7b +/- 1.2; 20.1b +/- 1.4 mm; media +/- S.E.M. for males A-F, respectively, P < 0.05). Spermatozoa from males with different mucus migration efficiency values produced different sperm populations at the oviduct reservoir of inseminated females (1,233 +/- 92.3 versus 28.8 +/- 17.0 spermatozoa of males with high and low relative migration efficiency, respectively, P < 0.02). Spermatozoa from males with different mucus migration efficiency values have different fertilization rates of IVM oocytes transferred to oviduct (47/96 (49.0%) versus 25/91 (27.5%) for males with high and low relative migration efficiency, respectively, P < 0.05). Cumulative results suggest that sperm migration in cervical mucus is related to the ability of spermatozoa to colonize the oviduct and to fertilize matured oocytes in vivo.