Different Stages Of Reproduction Research Articles

Microscopic Analysis of Nuclear Speckles in a Viviparous Reptile.

Nuclear speckles are compartments enriched in splicing factors present in the nucleoplasm of eucaryote cells. Speckles have been studied in mammalian culture and tissue cells, as well as in some non-mammalian vertebrate cells and invertebrate oocytes. In mammals, their morphology is linked to the transcriptional and splicing activities of the cell through a recruitment mechanism. In rats, speckle morphology depends on the hormonal cycle. In the present work, we explore whether a similar situation is also present in non-mammalian cells during the reproductive cycle. We studied the speckled pattern in several tissues of a viviparous reptile, the lizard Sceloporus torquatus, during two different stages of reproduction. We used immunofluorescence staining against splicing factors in hepatocytes and oviduct epithelium cells and fluorescence and confocal microscopy, as well as ultrastructural immunolocalization and EDTA contrast in Transmission Electron Microscopy. The distribution of splicing factors in the nucleoplasm of oviductal cells and hepatocytes coincides with the nuclear-speckled pattern described in mammals. Ultrastructurally, those cell types display Interchromatin Granule Clusters and Perichromatin Fibers. In addition, the morphology of speckles varies in oviduct cells at the two stages of the reproductive cycle analyzed, paralleling the phenomenon observed in the rat. The results show that the morphology of speckles in reptile cells depends upon the reproductive stage as it occurs in mammals.

Partial and asymmetrical reproductive isolation between two sympatric tropical shrub species: Cnidoscolus aconitifolius and C. souzae (Euphorbiaceae)

AbstractReproductive isolation is conferred by several barriers that occur at different stages of reproduction. Comprehensive reviews on the topic have identified that barriers occurring prior to zygote formation are often stronger than those that occur afterward. However, the overrepresentation of temperate perennial herbs in the current literature precludes any generalization of this pattern to plants that present other life forms and patterns of distribution. Here, we assessed reproductive isolation barriers and their absolute contribution to reproductive isolation and asymmetry in Cnidoscolus aconitifolius and C. souzae, two closely related tropical shrub species that co‐occur on the Yucatan peninsula. The reproductive barriers assessed were phenological mismatch, pollinator differentiation, pollen–pistil incompatibility (three pre‐zygotic barriers), fruit set failure, and seed unviability (post‐zygotic barriers). Reproductive isolation between the study species was found to be complete in the direction C. aconitifolius to C. souzae, but only partial in the opposite direction. One post‐zygotic barrier was the strongest example. Most barriers, particularly the pre‐zygotic examples, were asymmetrical and predicted the direction of heterospecific pollen flow and hybrid formation from C. souzae to C. aconitifolius. Both parental species, as well as the hybrids, were diploid and had a chromosome number 2n = 36. More studies with tropical woody perennials are required to fully determine whether this group of plants consistently shows stronger post‐zygotic barriers.

Cell adhesion function was altered during the seasonal regression of the seminiferous epithelium in the mink species Neovison vison.

Minks are seasonal breeders whose seminiferous epithelium undergoes regression through massive germ cell death, leaving only Sertoli cells and spermatogonial cells in the tubules. However, the molecular mechanisms that control this biological process remain largely unknown. This study describes a transcriptomic analysis of mink testes at various reproductive stages (active, regressing, and inactive). A comparison of seminiferous epithelium at different stages of reproduction shows that cell adhesion is altered during regression. In addition, genes and proteins involved in forming the blood-testis barrier (BTB) were examined in sexually active and inactive minks. The seminiferous epithelium in the testes of sexually inactive minks expressed occludin, but this expression was not discernibly observed in the testes of sexually active minks. There was no discernible expression of CX43 in the seminiferous epithelium in the testes of sexually inactive minks, but CX43 was expressed in the testes of sexually active minks. During the regression process, we observed a remarkable increase in the expression levels of Claudin-11, which is associated with Sertoli-germ cell junctions. In conclusion, these findings suggest a loss of Sertoli-germ cell adhesion, which may regulate postmeiotic cell shedding during testicular regression in mink.

Mothers modify the cost of reproduction by dynamic changes in antioxidant function and filial cannibalism.

Investment in current reproduction may negatively influence subsequent fitness. Oxidative stress has been proposed as a potential mediator of this trade-off between current and future reproductive success. However, evidence of reproduction causing oxidative stress is limited, possibly owing to compensatory mechanisms that counteract oxidative insults. Here we test the idea that organisms protect against oxidative challenges through a dynamic interaction between behavioural and physiological adjustments at different stages of reproduction. To test this idea, we manipulated maternal care in the mouthbrooding cichlid fish Astatotilapia burtoni by allowing females to continue care (brooders) or by preventing care (non-brooders). We found that brooders depleted the pool of antioxidants as brood care progressed; however, we only observed increased oxidative DNA damage at the early stage of care relative to non-brooders, possibly owing to upregulated antioxidant protection during later stages of care. Most brooders adjusted parental investment by consuming some of their offspring during mouthbrooding. Intriguingly, the level of filial cannibalism was positively related to liver antioxidant function. These changes in antioxidant function and filial cannibalism allow parents to manage the cost of reproduction and are important for our understanding of how oxidative stress mediates life-history trade-offs.

Mycotoxic effects of medicinal plants on the asexual reproduction of Aspergillus nigar ATCC 1015

Medicinal plants are tremendous source in herbal medicine for treatment of diverse range of disease, due to increasing rate of microbial infections their in vitro antimicrobial activity was analyzed. Mycotoxic effect of aqueous extract of medicinal plants Zatartia multiflora, Thymus vulgaris and Psammogeton canescens on asexual life cycle of Aspergillus nigar ATCC (American Type Culture Collection) 1015 were analyzed. To investigate the in vitro antifungal activity of Z. multiflora, T. vulgaris and P. canescens aqueous extract with three dilutions 0.13, 0.25 and 0.50% were prepared and their antifungal activity on three reproductive stages spore germination, mycelia elongation and sporulation (spore viability) of Aspergillus nigar ATCC 1015 were checked and compare with standard drug Miconazole. Plants under study possess antifungal activity that varied at different stages of reproduction, the intensity of inhibitory effects varied with the species and the concentration of extract used. P. canescens has remarkable inhibitory effects on spore germination and mycelia elongation with increase in concentration as compared to T. vulgaris and Z. multiflora. P. canescens also has well enough antifungal activity on sporulation it completely retards the spore formation at 0.50% and linear decrease in spores viability was recorded with the rise in extract amount in the medium while T. vulgaris and Z. multiflora also significantly affect spore formation and viability of spores. The maximum reduction in spore formation and viability of spore was recorded at 0.50% extract concentration i.e., 35.10 %and 64.31 %, respectively, in Zataria multiflora extract with respect to control. The standard drug Miconazole possesses splendid antifungal activity at all three stages of Aspergillus nigar strain. Hence A. nigar is extremely sensitive to Miconazole and P. canescens while T. vulgaris and Z. multiflora have significant inhibitory effects on spore germination, sporulation and on spore viability reproductive stages of Aspergillus nigar ATCC 1015.

Basis blood indices, serum biochemical profiles, antioxidant and oxidative profiles of endangered local buffaloes of Andaman and Nicobar Islands at different stages of reproduction

Andaman and Nicobar Islands (ANI) have non-defined and non-descriptive breed of buffaloes. Andaman local buffaloes (ALB) are distributed in Andaman group of Islands and few numbers are available in Campbell Bay and Nicobar group of Islands. Andaman local buffaloes represent an admixture of different Indian breeds that had been brought to these islands in different phases of inhabitation and rehabilitation of migrated people. It is believed that the ALBs have the inheritance from Murrah, Nagpuri, Bhadawari and Marathwada. It is unique buffalo, well adapted to special type of tropical humid island climatic and environmental condition. The present study was designed to standardise the normal reference haematological and biochemical ranges in different stages of reproduction of Andaman local buffaloes which were maintained in the Andaman Districts of ANI, India from April 2019 to March 2020. In this study, haematological parameters, biochemical indices and antioxidant and oxidative stress profiles were estimated in healthy, normal physiological ALBs in different reproductive stages. The present study results clearly indicated that the values of haematological, biochemical and antioxidant profiles fell under the normal physiological ranges. The results of this study may serve as the reference values in which alterations due to metabolic, nutrient deficiency, physiological and health status can be compared for diagnostic and therapeutic purposes for ALBs in ANI and its neighboring countries or other parts of the country with similar environmental and climatic conditions.

THE ROLE OF INFORMATION TECHNOLOGY IN THE ENTERPRISE MANAGEMENT SYSTEM IN THE AGRICULTURAL SECTOR AT THE PRESENT STAGE

The article examines modern approaches to solving the problem of using information technologies in the management of agricultural business, which is an urgent direction for improving the management system in the context of the implementation of national standards in the field of digitalization of the economy. The essence and content of the approaches used to collect and process information approaches are revealed, their advantages and disadvantages are noted. The direction of the use of innovative information platforms has been substantiated, contributing to the use of innovative software automated products for making managerial decisions on the provision of agricultural production with materials at different stages of reproduction, on cost optimization, rational use of financial, material and labor resources. The directions of using methods and techniques of digital information technologies in organizations of the agricultural industry in a certain future are determined, which is associated with the regulation of the expected results from agricultural production in the future.

Plasma levels of luteinizing hormone and prolactin in relation to double brooding in Great Tit (Parus major)

The reproductive behaviors of birds are mainly controlled by the hypothalamus-pituitary-gonad axis. Many studies have shown that reproductive hormones are tightly linked to the breeding sub-stages. However, only a few studies have examined the temporal trend of hormone levels among different reproductive stages in multiple brooded species. We investigated the changes in plasma luteinizing hormone (LH) and prolactin (PRL) concentrations during different reproductive stages of the facultative double-brooded Great Tit (Parus major). We found that the concentrations of LH and PRL in females were significantly higher than those in males. Females had significantly higher LH and lower PRL concentrations in the pre-breeding period than in the first/second brooding periods, and there were no significant changes between the first and second brooding periods. The concentrations of LH and PRL in males had no significant difference between the pre-breeding period and the first brooding periods, while LH and PRL concentrations in the second brooding period were significantly higher than those in the first brooding period. We conclude that there are sex-based differences between LH and PRL at different stages of reproduction. The changes in LH and PRL in both males and females should be related to their physiological functions. Especially for males, individuals with higher levels of LH and PRL are more likely to maintain second clutches.

Morphometrical study of the reproductive tract in Boran (Bos indicus) heifers in Ethiopia

Boran breed is the most suitable type of cattle breed for arid and semi-arid regions of Ethiopia due to their adaptive characteristics. Understanding their reproductive anatomy is important for successful reproductive management and has many implications for the application of assisted reproductive technology, and interpretation of physiological changes at different stages of their reproductive cycle. In this study, data of the anatomical structures of the reproductive organs of 20 Boran heifers were measured and characterized at different stages of reproduction. The mean (±SE) length (L) of the vagina, cervix, and body of uterus were 13.17±2.98 cm, 7.19±1.28 cm, and 6.70±1.08cm, respectively. The mean (±SE) length of the right uterine horn and oviduct was 18.47 ±2.54 and 18.17 ±1.27cm, respectively and that of the left were 18.05±2.73 and 17.45±1.80 cm, respectively. The mean ±SE weight (W) of right and left ovaries were 2.44±1.51 gm and 2.44±1.51 gm, respectively. The mean ±SE Length x Width x Thickness of the right ovary was 2.10±0.59 x 1.75±0.35 x 0.83±0.36 and that of the left was 1.97±0.41 x 1.58±0.29 x 0.67±0.33 cm. The mean (±SE) weight of the whole reproductive organ (without the vulva) was 301.35±66.34gm. The ovarian size was influenced by the presence of the corpus luteum(CL) usually larger with its presence.

Transcriptome Profiling of the Pacific Oyster Crassostrea gigas Visceral Ganglia over a Reproduction Cycle Identifies Novel Regulatory Peptides.

The neuropeptides involved in the regulation of reproduction in the Pacific oyster (Crassostrea gigas) are quite diverse. To investigate this diversity, a transcriptomic survey of the visceral ganglia (VG) was carried out over an annual reproductive cycle. RNA-seq data from 26 samples corresponding to VG at different stages of reproduction were de novo assembled to generate a specific reference transcriptome of the oyster nervous system and used to identify differentially expressed transcripts. Transcriptome mining led to the identification of novel neuropeptide precursors (NPPs) related to the bilaterian Eclosion Hormone (EH), crustacean female sex hormone/Interleukin 17, Nesfatin, neuroparsin/IGFBP, prokineticins, and urotensin I; to the protostome GNQQN, pleurin, prohormones 3 and 4, prothoracotropic hormones (PTTH), and QSamide/PXXXamide; to the lophotrochozoan CCWamide, CLCCY, HFAamide, and LXRX; and to the mollusk-specific NPPs CCCGS, clionin, FYFY, GNamide, GRWRN, GSWN, GWE, IWMPxxGYxx, LXRYamide, RTLFamide, SLRFamide, and WGAGamide. Among the complete repertoire of NPPs, no sex-biased expression was observed. However, 25 NPPs displayed reproduction stage-specific expression, supporting their involvement in the control of gametogenesis or associated metabolisms.

Late-stage pregnancy reduces upper thermal tolerance in a live-bearing fish.

Upper thermal limits are considered a key determinant of a population's ability to persist in the face of extreme heat events. However, these limits differ considerably among individuals within a population, and the mechanisms underlying this differential sensitivity are not well understood. Upper thermal tolerance in aquatic ectotherms is thought to be determined by a mismatch between oxygen supply and the increased metabolic demands associated with warmer waters. As such, tolerance is expected to decline during reproduction given the heightened oxygen demand for gamete production and maintenance. Among live-bearing species, upper thermal tolerance of reproductive adults may decline even further after fertilization due to the cost of meeting the increasing oxygen demands of developing embryos. We examined the upper thermal tolerance of live-bearing female Trinidadian guppies at different stages of reproduction and found that critical thermal maximum was similar during the egg yolking and early embryos stage but then declined by almost 0.5°C during late pregnancy when oxygen demands are the greatest. These results are consistent with the hypothesis that oxygen limitation sets thermal limits and show that reproduction is associated with a decline in upper thermal tolerance.

Особенности влияния бета-адреномиметика гинипрала на радикальную активность нейтрофилов в крови женщин на разных этапах репродукции

In recent years, the idea about the physiological significance of neutrophils, including during pregnancy and childbirth, has evolved significantly. There is an opinion that in the course of pregnancy, the activity of non-specific cellular immunity increases, which, in addition to performing a protective function, forms a mode of contractile activity of the uterus that is optimal for child-bearing. In obstetric practice, in order to reduce uterine hypertonicity in the treatment of miscarriage, β-adrenergic agonists are widely used. However, many aspects of their influence on the mother and the foetus remain insufficiently studied. The aim of this paper was to study the effect of Gynipral (selective β2-adrenergic agonist) on the intensity of latex-induced respiratory burst of venous blood neutrophils in women at different stages of reproduction. Using the chemiluminescence method, we showed for the first time that Gynipral, depending on the stage of reproduction, has multidirectional effect on the latex-induced radical activity of neutrophils in the venous blood of women in vitro. At a low level of radical reaction of neutrophils to latex (in the follicular phase of the cycle, during pregnancy and, which is especially important, during childbirth), Gynipral enhances the oxidative activity of cells; at a high level of radical reaction of neutrophils (during the luteal phase of the cycle and after childbirth), Gynipral inhibits it. It can be assumed that in women, catecholamines (adrenaline) during pregnancy through β2- and/or β3-adrenergic receptors increase the ability of neutrophils to produce activated forms of oxygen, while after delivery they reduce this ability. Such changes in receptor activation may be associated with the phenomenon of switching of β-adrenergic receptor coupling from Gs protein to Gi protein, which is important for regulatory mechanisms. For citation: Polezhaeva T.V., Paturova I.G., Zaytseva O.O., Solomina O.N., Khudyakov A.N., Sergushkina M.I., Dmitrieva S.L., Tsirkin V.I. Effect of Beta-Adrenergic Agonist Gynipral on the Radical Activity of Neutrophils in the Blood of Women at Different Stages of Reproduction. Journal of Medical and Biological Research, 2021, vol. 9, no. 2, pp. 171–181. DOI: 10.37482/2687-1491-Z055

Seasonally related metabolic changes and energy allocation associated with growth and reproductive phases in the liver of male goldfish (Carassius auratus)

Reproduction and growth follow a seasonal pattern in many fish species involving changes in gonadal development, growth, and metabolism. Significant metabolic energy is needed during gametogenesis in both female and male to produce hundreds of eggs and billions of sperms. Seasonal variations are controlled by the hormones of brain-pituitary-peripheral axis and are accompanied by significant metabolic changes. There is evidence that GnRH and GnIH are among the key neurohormones that regulate the reciprocal control of growth and reproduction. The objective of this study was to investigate changes in metabolic profile and energy allocation patterns at different stages of reproduction, using goldfish as a model organism and LC-MS as analytical platform for metabolic analysis. Goldfish undergoes a clear seasonal cycle of growth and reproduction. In vivo experiments were conducted at three different time point of the annual cycle: regressed gonadal phase (peak growth phase), mid gametogenesis and late gametogenesis. Emphasis is placed on changes in liver metabolic pathways to energetically sustain the physiological processes related to growth and reproduction. Moreover, we tested the hypothesis that GnRH and GnIH may play a role in the regulation of metabolism by investigating acute effects of these peptides at different stages of reproductive cycle. SignificanceThe findings in this paper provide novel information on the seasonal changes in basal metabolism during different stages of reproductive cycle, and evidence for differential allocation of energy during reciprocal control of reproduction and growth in goldfish. Chemometrics combined with pathway-driven bioinformatics elucidated a shift in the metabolic profile, indicating distinct patterns of energy allocation in the reproductive and growth seasons. Furthermore, to our knowledge this is the first study to provide evidence for a possible regulatory role of GnRH and GnIH in liver metabolism and energy allocation patterns associated with growth and reproductive processes. Together our findings present a framework for better understanding of the hormonally induced changes in metabolism to energetically sustain growth and reproduction in fish and other oviparous species undergoing seasonal cycle.

Histomorphological Studies on the Different Nuclei of Hypothalamus of Indian Buffalo

Background: Hypothalamus is an integral part of the hypothalamo-hypophyseal ovarian axis. It contains several small nuclei that have been implicated in several specialized functions. It is the master endocrine gland because it regulates the activity of the pituitary. The present investigation was planned to elucidate the histomorphological details of different nuclei in the hypothalamus of Indian buffaloes. Methods: The hypothalami of buffaloes (n =52) were collected from local abattoirs and Teaching Veterinary Clinical Complex, GADVASU, Ludhiana. The tissue samples were collected from three levels i.e. the supraoptic, tuberal and the mamillary region of the hypothalamus and processed for paraffin sectioning and the sections were stained with various stains for histomorphological studies. Result: The well-defined cell groups or nuclei were identified both in the coronal and sagittal sections of the hypothalamus in all the reproductive phases. Eight nuclei were distinctly recognized in buffalo hypothalamus at three levels in the coronal sections of the hypothalamus. At the level of optic chiasma, the nuclei were paraventricular nucleus (PVN), supraoptic nucleus (SON) and preopticnucleus (PON); at the tuberal region, there were arcuate nucleus (AN) and ventromedial nucleus (VMN) and at the mammillary region, the lateral mammillary nucleus (LMN), medial mammillary nucleus (MMN) and posterior hypothalamic nucleus (PHN) were identified. Most of the nuclei consisted of a loose or compact heterogeneous collection of neurons. The neurons of the different nuclei were of variable shape. The cytoplasm contained a varied amount of Nissl material. The neurosecretory substance was peripheral in position. Small to large-sized blood vessels were observed in between the neuronal substance. The size of the neurons varied during different stages of reproduction.

Parental dependence on the nest's spatial cues in offspring recognition decreases with nestling growth in the azure-winged magpie.

In altricial birds, to address which cues are used by parents to recognize their offspring, and when they switch between cues during reproduction, it has not been well determined. In this study, we address this question in a Tibetan population of the azure-winged magpie Cyanopica cyanus, by examining the dependence of parents on a nest’s spatial position in offspring recognition. During the egg and nestling phases, azure-winged magpie nests were translocated to new positions across various distances from their original site, and parental responses to the translocated nests were investigated. Our findings show that a nest’s spatial position is not connected with the survival of its young, but might be used as a cue in parental offspring recognition. When nests are translocated to a new position within a certain distance, parents could recognize their nests and returned to resume their parenting behaviors. Parental dependence on the nest’s spatial position in offspring recognition is higher during the egg phase than during the nestling phase, and it decreases with the growth of nestlings. After nestlings reach a certain age, the nest’ s spatial position was no longer used by parents as the single cue for offspring recognition. These findings suggest that azure-winged magpies switch their cues in offspring recognition during the different stages of reproduction. After parent–offspring communication has been established, the offspring’s phenotypic traits may become a more reliable cue than the nest’s spatial position in offspring recognition.

Intensity of Latex-Induced Respiratory Burst of Neutrophils in the Venous Blood of Women at Different Stages of Reproduction

We studied the intensity of respiratory burst of neutrophils in the venous blood of women at different stages of reproduction using the chemiluminescent method (BHL-07). The analysis of the of luminol-dependent latex-induced luminescence parameters demonstrated that the neutrophils of pregnant women are in the primed state and equally respond to latex-mediated induction during both normal pregnancy and in case of threatened miscarriage or premature birth. However, childbirth leads to the deactivation of neutrophils, while the intensity of active radical generation does not significantly differ from that in non-pregnant women.

Quantitative analysis of fish and invertebrate assemblage dynamics in association with a North Sea oil and gas installation complex

Decommissioning of offshore infrastructure has become a major issue facing the global offshore energy industry. In the North Sea alone, the decommissioning liability is estimated at £40 billion by 2040. Current international policy requires removal of offshore infrastructure when their production life ends; however, this policy is being questioned as emerging data reveal the importance of these structures to fish and invertebrate populations. Indeed, some governments are developing ‘rigs-to-reef’ (RTR) policies in situations where offshore infrastructure is demonstrated to have important environmental benefits. Using Remotely Operated Vehicles (ROVs), this study quantified and analysed fish and invertebrate assemblage dynamics associated with an oil and gas (O&G) complex in the Dogger Bank Special Area of Conservation (SAC), in the North Sea, Germany. We found clear depth zonation of organisms: infralittoral communities (0–15 m), circalittoral assemblages (15–45 m) and epi-benthic communities (45–50 m), which implies that ‘topping’ or ‘toppling’ decommissioning strategies could eliminate communities that are unique to the upper zones. Sessile invertebrate assemblages were significantly different between structures, which appeared to be driven by both biotic and abiotic mechanisms. The O&G complex accommodated diverse and abundant motile invertebrate and fish assemblages within which the whelk Buccinium undatum, cod fish Gadus morhua and lumpsucker fish Cyclopterus lumpus used the infrastructure for different stages of reproduction. This observation of breeding implies that the structures may be producing more fish and invertebrates, as opposed to simply acting as sites of attraction (sensu the ‘attraction vs production’ debate). At present, there are no records of C. lumpus spawning at such depth and distance from the coast, and this is the first published evidence of this species using an offshore structure as a spawning site. Overall, this study provides important new insight into the role of offshore O&G structures as habitat for fish and invertebrates in the North Sea, thereby helping to inform decommissioning decisions.

Nest-mediated parental care in a marine fish: Are large-scale nesting habitats selected and do these habitats respond to small-scale requirements?

Fishes have evolved various reproductive strategies including mechanisms that involve parental care and demersal eggs laid into nests. Symphodus ocellatus has a seasonal reproduction period during which large, dominant males become territorial and build nests with fragments of algae, where they attract females to spawn and provide care to the developing eggs. Based on the hypothesis that the S. ocellatus males choose the reproductive habitat based on some characteristics of the substrate, here we assessed whether, on a coastal area scale, the distribution of this species changes during the reproductive period because of the selection of some suitable sites or substrates, and whether the nesting microhabitat used by this species responding to certain requirements in relation to different characteristics. From April to September 2010, at four locations and on three substrate types, the fish were counted in three periods related to different stages of reproduction. Furthermore, several physical and biological variables have been recorded around numerous nests to select those with more recurrence. We found that S. ocellatus prefers to live on rocky substrates populated by photophilic algae, regardless of the phases of the reproductive cycle. We identified depth (1.7–3.2 m), the presence of a hole, a 10–20 cm algal canopy, and high algal coverage of Dyctiotales as nest requirements. S. ocellatus is mostly distributed in coastal sites sheltered from the action of waves. This allows the construction and maintenance of nests and the possibility to remain in a water temperature range similar to the reproductive physiological constraints.

How do helpers help? Helper contributions throughout the nesting cycle in the cooperatively breeding brown-headed nuthatch

Breeder investment in offspring reflects a trade-off between the benefits realized from current reproductive efforts and the benefits expected from future reproductive opportunities. When assisted by nonbreeding helpers that provide care for offspring, breeders may modify reproductive investments to minimize the costs of producing offspring, or in ways that maximize productivity and offspring survival. How helpers assist breeders can vary with different stages of reproduction, and how breeders alter investment in response to helpers may change depending on the stage of reproduction. We assessed how helpers contribute to reproduction and how breeders alter their investment in response to helper contributions in the cooperatively breeding brown-headed nuthatch (Sitta pusilla). We assessed helper contributions across three stages of reproduction: (1) nest excavation, (2) maternal egg production, and (3) nestling care and development at days 8–12 post-hatching, a period of rapid nestling growth. We also investigated how breeders responded to helper contributions and the relationship of helper behavior with breeders’ reproductive success. Helpers contributed to offspring care but not nest excavation. Breeders assisted by helpers did not alter investments in nest excavation, offspring production, or offspring care. As a result, offspring raised by cooperative groups received more food and weighed more. Nests with helpers were more likely to fledge at least one offspring, even when considering variation in territory characteristics and breeder experience. Results indicate breeders likely benefit from the favorable breeding conditions helpers provided for current breeding efforts, which influenced the quality of offspring produced and their likelihood of fledging in this study. Helpers may contribute to breeders’ reproductive effort during many stages of reproduction. The presence of nonbreeding helpers should therefore influence the investments made by breeders during different stages of breeding. Investment decisions in one stage should furthermore influence later investment decisions. We demonstrated that helpers assisted breeders primarily during the offspring rearing stage in brown-headed nuthatches (Sitta pusilla), a facultative cooperative breeder. Breeders with helpers maintained their level of investments in offspring similar to the investments documented for breeders without helpers. As a result, chicks in nests with helpers received more food and were heavier, and adults with helpers were more likely to fledge at least one young. Our results suggest that the combined effects of parental and helper investment provided benefits for current broods with potentially important survival consequences for offspring.

Способность гинипрала изменять негеномное влияние дидрогестерона на свободнорадикальную активность нейтрофилов женщин на разных этапах репродукции

Способность гинипрала изменять негеномное влияние дидрогестерона на свободнорадикальную активность нейтрофилов женщин на разных этапах репродукции