Dietary supplementation with integral chia and flax flours ameliorates systemic inflammation.

INTRODUCTION: Chia and flax seeds are rich in alphalinolenic acid (ALA), which is bioconverted into the active derivatives eicosapentaenoic (EPA) and docosahexaenoic (DHA) having multiple beneficial effects. However, there is limited knowledge about the antiinflammatory effects of chia and flax integral flours diets rich in ALA. OBJECTIVE: The study aimed to evaluate the antiinflammatory effect of dietary supplementation with integral chia and flax flours in a murine model of LPSinduced systemic inflammation. METHODS: Balb/c mice were distributed into three groups: diet A (control), diet B (supplemented with integral chia flour), and diet C (supplemented with integral flax flour). Nutritional, hematological, and biochemical determinations were performed. ALA, EPA, and DHA were assessed by GC-MS in the liver, brain, cardiac and skeletal muscles. NF-kB immunoassays were performed in kidney, liver, and peritoneal macrophages, respectively. The phagocytic capacity was determined in peritoneal macrophages and the expression of the pro- and anti-inflammatory cytokines was assessed by RT-qPCR in the kidney, liver, and spleen. RESULTS: Diets B and C exhibited optimal nutritional adequacy and caused increased levels of ALA, EPA, and DHA in critical tissues compared to the control. The phagocytic capacity of murine peritoneal macrophages (p< 0.01) and IL-10 transcription increased, whereas the expression of NF-κB, IL-1Β, IL-6, and TNF-α decreased in animals fed both experimental diets. CONCLUSIONS: This work contributes to the current knowledge of the anti-inflammatory effects of chia and flax integral flours rich in ALA and reinforces the health advantages of their consumption.

Introducción: Las semillas de chía y lino son ricas en ácido alfa-linolénico (ALA), sus derivados activos eicosapentaenoico (EPA) y docosahexaenoico (DHA) ejercen probados efectos beneficiosos. Existe un conocimiento limitado sobre los efectos protectores de ambas semillas bajo la forma de harinas integrales, siendo de particular interés el efecto antiinflamatorio. OBJETIVO: El objetivo de este trabajo fue evaluar el efecto antiinflamatorio de la suplementación dietaria con harinas integrales de semillas de chía y lino en un modelo murino de inflamación sistémica inducido por LPS. Métodos: Ratones de la cepa Balb/c fueron distribuidos en tres grupos: dieta A (control), dieta B (suplementada con harina integral de chía) y dieta C (suplementada con harina integral de lino). Se efecturaron determinaciones nutricionales, hematológicas y bioquímicas. El contenido de ALA, EPA y DHA en hígado, cerebro, corazón y músculo esquelético se determinó por cromatografía GC-MS. Se realizó la inmunodetección de NF-kB en macrófagos peritoneales, riñón e hígado. Se determinó la capacidad fagocítica de macrófagos peritoneales y se evaluó la expresión de citoquinas pro y antiinflamatorias por RT-qPCR en riñón, hígado y bazo. RESULTADOS: Las dietas B y C mostraron una adecuación nutricional óptima y generaron niveles elevados de ALA, EPA y DHA en tejidos críticos. La capacidad fagocítica de los macrófagos peritoneales (p< 0.01) y la transcripción de IL-10 aumentó, mientras que la expresión de NF-κB, IL-1Β, IL-6 y TNF-α disminuyó en animales de los grupos B y C. CONCLUSIONES: Este trabajo contribuye al conocimiento actual de los efectos antiinflamatorios de ambas harinas integrales y refuerza los beneficios de su consumo.

A call-to-action to assist in efforts to protect owl monkeys (Aotus spp.).

The majority of the 11 species of owl monkeys (Aotus spp.) have declining populations or are listed as data deficient. Deforestation due to agriculture, development, or logging poses threats to owl monkeys throughout their range. In some areas, Aotus are hunted for bushmeat or trapped for the wildlife trade. In Colombia, the country with the greatest number of Aotus species, owl monkeys are also threatened by civil unrest. To help combat these challenges, nonprofit organizations and field researchers in habitat countries have successfully implemented a variety of conservation projects such as censusing and monitoring owl monkey populations, establishing protected areas, reforesting degraded areas, filing lawsuits to protect wild populations, helping law enforcement with environmental regulation, and promoting environmental education. We highlight some of the conservation successes and suggest actions people around the world can take to contribute to these important efforts.

The effects of resistance training to near failure on strength, hypertrophy, and motor unit adaptations in previously trained adults.

Limited research exists examining how resistance training to failure affects applied outcomes and single motor unit characteristics in previously trained individuals. Herein, resistance-trained adults (24 ± 3 years old, self-reported resistance training experience was 6 ± 4 years, 11 men and 8 women) were randomly assigned to either a low-repetitions-in-reserve (RIR; i.e., training near failure, n = 10) or high-RIR (i.e., not training near failure, n = 9) group. All participants implemented progressive overload during 5 weeks where low-RIR performed squat, bench press, and deadlift twice weekly and were instructed to end each training set with 0-1 RIR. high-RIR performed identical training except for being instructed to maintain 4-6 RIR after each set. During week 6, participants performed a reduced volume-load. The following were assessed prior to and following the intervention: (i) vastus lateralis (VL) muscle cross-sectional area (mCSA) at multiple sites; (ii) squat, bench press, and deadlift one-repetition maximums (1RMs); and (iii) maximal isometric knee extensor torque and VL motor unit firing rates during an 80% maximal voluntary contraction. Although RIR was lower in the low- versus high-RIR group during the intervention (p < 0.001), total training volume did not significantly differ between groups (p = 0.222). There were main effects of time for squat, bench press, and deadlift 1RMs (all p-values < 0.05), but no significant condition × time interactions existed for these or proximal/middle/distal VL mCSA data. There were significant interactions for the slope and y-intercept of the motor unit mean firing rate versus recruitment threshold relationship. Post hoc analyses indicated low-RIR group slope values decreased and y-intercept values increased after training suggesting low-RIR training increased lower-threshold motor unit firing rates. This study provides insight into how resistance training in proximity to failure affects strength, hypertrophy, and single motor unit characteristics, and may inform those who aim to program for resistance-trained individuals.

Bibliometric analysis of publications discussing the use of the artificial intelligence technique agent-based models in sustainable agriculture.

The purpose of this article consists of analyzing publications discussing the use of agent-based artificial intelligence models in sustainable agriculture research. The analysis involved bibliometric indicators and the Rstudio software with Bibliometrix library. The methodology is descriptive with a quantitative approach. Scientific databases SCOPUS and Web of Science were consulted and the PRISMA methodology was used during the selection process. This led to finding 86 publications that met the inclusion criteria. Amongst the results, United States was listed as the country with the highest production of scientific material, although France had a higher impact. Additionally, the bibliographical resources that help promote scientific development are open source. It was concluded that the agent-based model has been adopted to simulate different scenarios, which help decision-makers to formulate public policies in favor of sustainable agriculture. This optimizes the use of natural resources and reduces negative consequences for the environment, while also delivering value for the stakeholders of the agricultural system.

Production and Characterization of Biocomposite Films of Bacterial Cellulose from Kombucha and Coated with Chitosan.

The purpose of this research is to produce and characterize bacterial cellulose (BC) films coated with chitosan (BC-CH). BC films were produced in a fermentation medium based on Camellia sinensis tea and dextrose (12 days at 25 °C) and subsequently treated with coating-forming solutions (CFSs) based on chitosan (BC-CH 0.5%, BC-CH 1.0%, and BC-CH 1.5%). As a result, the FTIR spectra of BC and BC-CH 1.5% showed the main characteristic bands of cellulose and chitosan. In the physicochemical characterization of the films, it was found that the incorporation of the chitosan coatings did not affect the thickness; however, it decreased the luminosity (L*) and increased redness (a*), yellowness (b*), and opacity (75.24%). Additionally, the light absorption properties in the UV-Vis range were improved. Furthermore, the application of the CFSs increased: the solubility (64.91%), the antimicrobial activity against S. aureus (6.55 mm) and E. coli (8.25 mm), as well as the antioxidant activity (57.71% and 24.57% free radical scavenging activity), and the content of total phenols (2.45 mg GAE/g). Finally, our results suggest that the BC-CH films developed in the present study show a potential application as active packaging material for food.

South American snake venoms with abundant neurotoxic components. Composition and toxicological properties. A literature review.

In South America there are three snake genera with predominantly neurotoxic venoms: Crotalus, Micrurus and Hydrophis, which include nine species/subspecies, 97 species and a single marine species, respectively. Although accidents with neurotoxic venoms are less frequent than those with anticoagulant, cytotoxic or necrotic venoms (e.g. from Bothrops), they are of major public health importance. Venoms from genus Crotalus have been extensively studied, while data on the venoms from the other two genera are very limited, especially for Hydrophis. The venoms of North and South American Crotalus species show biochemical and physiopathological differences. The former species cause bothrops-like envenomation symptoms, while the latter mainly have neurotoxic and myotoxic effects, leading to respiratory paralysis and, occasionally, renal failure by myoglobinuria and death, often with no local lesions. Micrurus and Hydrophis also cause neurotoxic envenomations. Many studies have isolated, identified and characterized new enzymes and toxins, thus expanding the knowledge of snake venom composition. The present review summarizes the currently available information on neurotoxic venoms from South American snakes, with a focus on protein composition and toxicological properties. It also includes some comments concerning potential medical applications of elapid and crotalic toxins.

A Two-Stage Data-Driven Spatiotemporal Analysis to Predict Failure Risk of Urban Sewer Systems Leveraging Machine Learning Algorithms.

Risk-informed asset management is key to maintaining optimal performance and efficiency of urban sewer systems. Although sewer system failures are spatiotemporal in nature, previous studies analyzed failure risk from a unidimensional aspect (either spatial or temporal), not accounting for bidimensional spatiotemporal complexities. This is owing to the insufficiency of good-quality data, which ultimately leads to under-/overestimation of failure risk. Here, we propose a generalized methodology/framework to facilitate a robust spatiotemporal analysis of urban sewer system failure risk, overcoming the intrinsic challenges of data imperfections-e.g., missing data, outliers, and imbalanced information. The framework includes a two-stage data-driven modeling technique that efficiently models the highly right-skewed sewer system failure data to predict the failure risk, leveraging a bidimensional space-time approach. We implemented our analysis for Bogotá, the capital city of Colombia. We train, test, and validate a battery of machine learning algorithms-logistic regression, decision trees, random forests, and XGBoost-and select the best model in terms of goodness-of-fit and predictive accuracy. Finally, we illustrate the applicability of the framework in planning/scheduling sewer system maintenance operations using state-of-the-art optimization techniques. Our proposed framework can help stakeholders to analyze the failure-risk models' performance under different discrimination thresholds, and provide managerial insights on the model's adequate spatial resolution and appropriateness of decentralized management for sewer system maintenance.

Choline Glycerophospholipid-Derived Prostaglandins Attenuate TNFα Gene Expression in Macrophages via a cPLA2α/COX-1 Pathway.

Macrophages are professional antigen presenting cells with intense phagocytic activity, strategically distributed in tissues and cavities. These cells are capable of responding to a wide variety of innate inflammatory stimuli, many of which are signaled by lipid mediators. The distribution of arachidonic acid (AA) among glycerophospholipids and its subsequent release and conversion into eicosanoids in response to inflammatory stimuli such as zymosan, constitutes one of the most studied models. In this work, we used liquid and/or gas chromatography coupled to mass spectrometry to study the changes in the levels of membrane glycerophospholipids of mouse peritoneal macrophages and the implication of group IVA cytosolic phospholipase A2 (cPLA2α) in the process. In the experimental model used, we observed that the acute response of macrophages to zymosan stimulation involves solely the cyclooxygenase-1 (COX-1), which mediates the rapid synthesis of prostaglandins E2 and I2. Using pharmacological inhibition and antisense inhibition approaches, we established that cPLA2α is the enzyme responsible for AA mobilization. Zymosan stimulation strongly induced the hydrolysis of AA-containing choline glycerophospholipids (PC) and a unique phosphatidylinositol (PI) species, while the ethanolamine-containing glycerophospholipids remained constant or slightly increased. Double-labeling experiments with 3H- and 14C-labeled arachidonate unambiguously demonstrated that PC is the major, if not the exclusive source, of AA for prostaglandin E2 production, while both PC and PI appeared to contribute to prostaglandin I2 synthesis. Importantly, in this work we also show that the COX-1-derived prostaglandins produced during the early steps of macrophage activation restrict tumor necrosis factor-α production. Collectively, these findings suggest new approaches and targets to the selective inhibition of lipid mediator production in response to fungal infection.

Phospholipid Arachidonic Acid Remodeling During Phagocytosis in Mouse Peritoneal Macrophages.

Macrophages contain large amounts of arachidonic acid (AA), which distributes differentially across membrane phospholipids. This is largely due to the action of coenzyme A-independent transacylase (CoA-IT), which transfers the AA primarily from diacyl choline-containing phospholipids to ethanolamine-containing phospholipids. In this work we have comparatively analyzed glycerophospholipid changes leading to AA mobilization in mouse peritoneal macrophages responding to either zymosan or serum-opsonized zymosan (OpZ). These two phagocytic stimuli promote the cytosolic phospholipase A2-dependent mobilization of AA by activating distinct surface receptors. Application of mass spectrometry-based lipid profiling to identify changes in AA-containing phospholipids during macrophage exposure to both stimuli revealed significant decreases in the levels of all major choline phospholipid molecular species and a major phosphatidylinositol species. Importantly, while no changes in ethanolamine phospholipid species were detected on stimulation with zymosan, significant decreases in these species were observed when OpZ was used. Analyses of CoA-IT-mediated AA remodeling revealed that the process occurred faster in the zymosan-stimulated cells compared with OpZ-stimulated cells. Pharmacological inhibition of CoA-IT strongly blunted AA release in response to zymosan but had only a moderate effect on the OpZ-mediated response. These results suggest a hitherto undescribed receptor-dependent role for CoA-independent AA remodeling reactions in modulating the eicosanoid biosynthetic response of macrophages. Our data help define novel targets within the AA remodeling pathway with potential use to control lipid mediator formation.

A Lipidomic Perspective of the Action of Group IIA Secreted Phospholipase A2 on Human Monocytes: Lipid Droplet Biogenesis and Activation of Cytosolic Phospholipase A2α.

Phospholipase A2s constitute a wide group of lipid-modifying enzymes which display a variety of functions in innate immune responses. In this work, we utilized mass spectrometry-based lipidomic approaches to investigate the action of Asp-49 Ca2+-dependent secreted phospholipase A2 (sPLA2) (MT-III) and Lys-49 sPLA2 (MT-II), two group IIA phospholipase A2s isolated from the venom of the snake Bothrops asper, on human peripheral blood monocytes. MT-III is catalytically active, whereas MT-II lacks enzyme activity. A large decrease in the fatty acid content of membrane phospholipids was detected in MT III-treated monocytes. The significant diminution of the cellular content of phospholipid-bound arachidonic acid seemed to be mediated, in part, by the activation of the endogenous group IVA cytosolic phospholipase A2α. MT-III triggered the formation of triacylglycerol and cholesterol enriched in palmitic, stearic, and oleic acids, but not arachidonic acid, along with an increase in lipid droplet synthesis. Additionally, it was shown that the increased availability of arachidonic acid arising from phospholipid hydrolysis promoted abundant eicosanoid synthesis. The inactive form, MT-II, failed to produce any of the effects described above. These studies provide a complete lipidomic characterization of the monocyte response to snake venom group IIA phospholipase A2, and reveal significant connections among lipid droplet biogenesis, cell signaling and biochemical pathways that contribute to initiating the inflammatory response.

Exploring ultra-high concentrator photovoltaic Cassegrain-Koehler-based designs up to 6000×.

Ultra-High Concentrator Photovoltaic (UHCPV) designs with up to more than 6000× geometrical concentration and optical efficiency of 80% are demonstrated in this paper by means of ray tracing simulations. These are developed based on Cassegrain-Koehler concentrators [Opt. Lett.41(9), 1985 (2016)], with four pairs of paraboloid-hyperboloid mirrors and a central receiver composed of four Cartesian ovals of revolution. Designs at different geometrical concentrations are analyzed based on their aspect ratios (F-number). The most compact designs exhibit highest optical efficiencies. Moreover, a 3015× geometrical concentration one-cell prototype, made of aluminum and PMMA (poly(methyl methacrylate)), is fabricated and characterized indoors, achieving an effective concentration of 938 suns. This represents the CPV module with the highest geometrical concentration that has been experimentally investigated that could be found in the scientific literature.

A Lipidomic perspective of the action of group IIA secreted phospholipase A2 on human monocytes: lipid droplet biogenesis and activation of cytosolic phospholipase A2a

Phospholipase A2s constitute a wide group of lipid-modifying enzymes which display a variety of functions in innate immune responses. In this work, we utilized mass spectrometry-based lipidomic approaches to investigate the action of Asp-49 Ca2+-dependent secreted phospholipase A2 (sPLA2) (MT-III) and Lys-49 sPLA2 (MT-II), two group IIA phospholipase A2s isolated from the venom of the snake Bothrops asper, on human peripheral blood monocytes. MT-III is catalytically active, whereas MT-II lacks enzyme activity. A large decrease in the fatty acid content of membrane phospholipids was detected in MT III-treated monocytes. The significant diminution of the cellular content of phospholipid-bound arachidonic acid seemed to be mediated, in part, by the activation of the endogenous group IVA cytosolic phospholipase A2a. MT-III triggered the formation of triacylglycerol and cholesterol enriched in palmitic, stearic, and oleic acids, but not arachidonic acid, along with an increase in lipid droplet synthesis. Additionally, it was shown that the increased availability of arachidonic acid arising from phospholipid hydrolysis promoted abundant eicosanoid synthesis. The inactive form, MT-II, failed to produce any of the effects described above. These studies provide a complete lipidomic characterization of the monocyte response to snake venom group IIA phospholipase A2, and reveal significant connections among lipid droplet biogenesis, cell signaling and biochemical pathways that contribute to initiating the inflammatory response.

A Lipidomic perspective of the action of group IIA secreted phospholipase A2 on human monocytes: lipid droplet biogenesis and activation of cytosolic phospholipase A2a

Phospholipase A2s constitute a wide group of lipid-modifying enzymes which display a variety of functions in innate immune responses. In this work, we utilized mass spectrometry-based lipidomic approaches to investigate the action of Asp-49 Ca2+-dependent secreted phospholipase A2 (sPLA2) (MT-III) and Lys-49 sPLA2 (MT-II), two group IIA phospholipase A2s isolated from the venom of the snake Bothrops asper, on human peripheral blood monocytes. MT-III is catalytically active, whereas MT-II lacks enzyme activity. A large decrease in the fatty acid content of membrane phospholipids was detected in MT III-treated monocytes. The significant diminution of the cellular content of phospholipid-bound arachidonic acid seemed to be mediated, in part, by the activation of the endogenous group IVA cytosolic phospholipase A2a. MT-III triggered the formation of triacylglycerol and cholesterol enriched in palmitic, stearic, and oleic acids, but not arachidonic acid, along with an increase in lipid droplet synthesis. Additionally, it was shown that the increased availability of arachidonic acid arising from phospholipid hydrolysis promoted abundant eicosanoid synthesis. The inactive form, MT-II, failed to produce any of the effects described above. These studies provide a complete lipidomic characterization of the monocyte response to snake venom group IIA phospholipase A2, and reveal significant connections among lipid droplet biogenesis, cell signaling and biochemical pathways that contribute to initiating the inflammatory response.

Consequences of placentophagia by adult virgin male California mice (Peromyscus californicus).

Placentophagia increases parental motivation in sexually inexperienced adult female rodents. We hypothesized that placenta ingestion has similar effects in virgin male California mice (Peromyscus californicus), a monogamous rodent in which fathers provide extensive care for their offspring. To test this hypothesis, we administered either a conspecific's placenta in oil or oil alone to adult virgin males via oral gavage. One, 7 or 24 hours later, each male underwent a 1-hour behavior test with either an unfamiliar pup or a novel object marble), immediately after which the mouse was perfused and the brain collected. Neural activation (Fos-immunoreactivity) was quantified in brain regions involved in parental care (bed nucleus of the stria terminalis, medial preoptic area, amygdala). We found few significant effects of placenta treatment, but at 7 h post-gavage, placenta-treated males had decreased latencies to approach both pups and marbles, compared to oil-treated controls (p = 0.05). Placenta-treated males also showed lower Fos-immunoreactivity in the dorsal bed nucleus of the stria terminalis, irrespective of stimulus type, compared to controls, both 1 h (p = 0.04) and 7 h (p = 0.05) post-treatment. These results suggest that placentophagia does not directly affect paternal motivation but might increase willingness to interact with novel stimuli in virgin male California mice.

Sequestration of 9-Hydroxystearic Acid in FAHFA (Fatty Acid Esters of Hydroxy Fatty Acids) as a Protective Mechanism for Colon Carcinoma Cells to Avoid Apoptotic Cell Death.

Hydroxy fatty acids are known to cause cell cycle arrest and apoptosis. The best studied of them, 9-hydroxystearic acid (9-HSA), induces apoptosis in cell lines by acting through mechanisms involving different targets. Using mass spectrometry-based lipidomic approaches, we show in this study that 9-HSA levels in human colorectal tumors are diminished when compared with normal adjacent tissue. Since this decrease could be compatible with an escape mechanism of tumors from 9-HSA-induced apoptosis, we investigated different features of the utilization of this hydroxyfatty acid in colon. We show that in colorectal tumors and related cell lines such as HT-29 and HCT-116, 9-HSA is the only hydroxyfatty acid constituent of branched fatty acid esters of hydroxyfatty acids (FAHFA), a novel family of lipids with anti-inflammatory properties. Importantly, FAHFA levels in tumors are elevated compared with normal tissue and, unlike 9-HSA, they do not induce apoptosis of colorectal cell lines over a wide range of concentrations. Further, the addition of 9-HSA to colon cancer cell lines augments the synthesis of different FAHFA before the cells commit to apoptosis, suggesting that FAHFA formation may function as a buffer system that sequesters the hydroxyacid into an inactive form, thereby restricting apoptosis.

Gingival biotypes in Mexican students aged 17-19 years old and their associated anatomic structures, socio-demographic and dietary factors.

This was a cross-sectional study with 550 students aged 17-19 years old. Gingival biotype (GB) was classified as thin, thick, and mixed based on visual inspection. Biotypes were associated with anatomical parameters from the anterior teeth, including probing depth, keratinized gingiva (KG), and gingival attachment (GA). Upper lip distance, facial thirds, tooth shape, gingival recessions, and gummy smile (GS) were also measured. Other variables included sex, age, dietary intake, and oral hygiene habits. Prevalence of thin, thick, and mixed biotypes was 68.4%, 19%, and 12.5%, respectively. Recessions occurred most often in those with thin biotypes. GS was more often seen in men with thin biotypes and in women with thick biotypes. There was a relationship between thin biotypes and oval teeth, and between thick biotypes and square teeth. The lower facial third was larger in thin biotypes. Thin biotypes were also related to larger canines, larger lateral and central incisors, and less KG and GA. Conversely, thick biotypes were associated with shorter teeth and with more KG and GA. Dietary intake and dental hygienic were not significantly associated with GB. Morphologic and phenotypic characterization of GBs can be relevant when planning and performing common dental procedures (e.g., prosthetics, implants, and orthodontics).

Next-generation sequencing yields the complete organellar genomes of kelp Lessonia flavicans (Lessoniaceae, Phaeophyceae) from the Sub-Antarctic ecoregion of Magallanes, Chile.

The generitype Lessonia flavicans Bory is an endemic and important kelp from Sub-Antarctic Magellanic ecoregion that shows affinity to extreme salinity, temperature, and photoperiod conditions. Genomic analysis of L. flavicans from Rinconada Bulnes, Punta Arenas, Chile, resulted in the assembly of its organellar genomes. The L. flavicans complete mitogenome is 37,226 base pairs (bp) in length and contains 66 genes (GenBank accession number MN561186), the complete plastid genome is 130,085 bp and has 173 genes (MN561187) and the data assembled 8205 bp of the nuclear ribosomal cistron (MN561188). The organellar genomes are similar in structure and content to L. spicata (Suhr) Santelices and other Laminariales.

Behavioral and endocrine consequences of placentophagia in male California mice (Peromyscus californicus).

Ingestion of placenta by mammalian mothers can lead to changes in pain sensitivity, hormone levels, and behavioral responses to newborns. In some biparental mammals, males, in addition to females, ingest placenta when their offspring are born. In the monogamous, biparental California mouse (Peromyscus californicus), males first become attracted to placenta when cohabitating with their pregnant mate, and virgin males administered placenta are less neophobic than males given oil vehicle. In this study, we investigated the effects of placentophagia on pain sensitivity, anxiety-like behavior, behavioral responses to pups, and circulating corticosterone levels of both breeding and nonbreeding male California mice. We orally administered either a conspecific placenta or oil vehicle to male mice from three reproductive conditions (first-time fathers, first-time expectant fathers, and virgin males) and tested their pain sensitivity 1 h later, as well as their exploratory behavior and paternal responsiveness in an open field 4 h post-treatment. We measured plasma corticosterone immediately after the open-field test. We found that placenta-treated males, independent of reproductive condition, traveled significantly longer distances in the open field than males treated with oil, indicative of lower anxiety. Additionally, fathers had shorter latencies to approach and to care for pups (i.e., huddling and licking pups), and spent more time engaging in these behaviors, than did age-matched expectant fathers and virgin males, independent of treatment. We found no effect on plasma corticosterone levels or pain sensitivity as a result of either treatment or reproductive condition. These findings indicate that placenta ingestion decreases anxiety-related behaviors in male California mice, but might not influence pain sensitivity, paternal responsiveness, or plasma corticosterone concentrations.

Paternal Care in Biparental Rodents: Intra- and Inter-individual Variation.

Parental care by fathers, although rare among mmmals, can be essential for the survival and normal development of offspring in biparental species. A growing body of research on biparental rodents has identified several developmental and experiential influences on paternal responsiveness. Some of these factors, such as pubertal maturation, interactions with pups, and cues from a pregnant mate, contribute to pronounced changes in paternal responsiveness across the course of the lifetime in individual males. Others, particularly intrauterine position during gestation and parental care received during postnatal development, can have long-term effects on paternal behavior and contribute to stable differences among individuals within a species. Focusing on five well-studied, biparental rodent species, we review the developmental and experiential factors that have been shown to influence paternal responsiveness, and consider their roles in generating both intra- and inter-individual variation. We also review hormones and neuropeptides that have been shown to modulate paternal care and discuss their potential contributions to behavioral differences within and between males. Finally, we discuss the possibility that vasopressinergic and possibly oxytocinergic signaling within the brain, modulated by gonadal steroid hormones, may represent the "final common pathway" mediating effects of developmental and experiential variables on intra- and inter-individual variation in paternal care.

Effects of repeated pup exposure on behavioral, neural, and adrenocortical responses to pups in male California mice (Peromyscus californicus).

In biparental mammals, the factors facilitating the onset of male parental behavior are not well understood. While hormonal changes in fathers may play a role, prior experience with pups has also been implicated. We evaluated effects of prior exposure to pups on paternal responsiveness in the biparental California mouse (Peromyscus californicus). We analyzed behavioral, neural, and corticosterone responses to pups in adult virgin males that were interacting with a pup for the first time, adult virgin males that had been exposed to pups 3 times for 20min each in the previous week, and new fathers. Control groups of virgins were similarly tested with a novel object (marble). Previous exposure to pups decreased virgins' latency to approach pups and initiate paternal care, and increased time spent in paternal care. Responses to pups did not differ between virgins with repeated exposure to pups and new fathers. In contrast, repeated exposure to a marble had no effects. Neither basal corticosterone levels nor corticosterone levels following acute pup or marble exposure differed among groups. Finally, Fos expression in the medial preoptic area, ventral and dorsal bed nucleus of the stria terminalis was higher following exposure to a pup than to a marble. Fos expression was not, however, affected by previous exposure to these stimuli. These results suggest that previous experience with pups can facilitate the onset of parental behavior in male California mice, similar to findings in female rodents, and that this effect is not associated with a general reduction in neophobia.