Duration Of Embryonic Development Research Articles

Exploring Altitude's Influence: Contrasting Embryonic Development of Hyla annectans Jerdon in High and Low Altitude Environments

The study investigated the embryonic development of Hyla annectans Jerdon, a frog species, at high and low altitude breeding sites of Meghalaya, North East India. Results revealed significant differences in the duration of embryonic development and hatching between the two altitudes. Embryos at low altitude sites exhibited a faster development, hatching approximately four days earlier than those at high altitude sites. Early embryonic stages displayed similar characteristics in size between the two sites, but distinct differences emerged during later stages, notably in stages associated with heart development, muscular response, and gill circulation. Furthermore, metamorphosis completion varied between altitudes, with a shorter duration observed at low altitude compared to high altitude. Environmental conditions, particularly water properties, also differed significantly between the two sites. Water temperature and free carbon dioxide levels were higher at low altitude, while pH and dissolved oxygen levels were higher at high altitude. These findings suggest a potential influence of altitudinal gradients as environmental factors on embryonic development in H. annectans.

The Effect of Temperature on the Embryo Development of Cephalopod Sepiella japonica Suggests Crosstalk between Autophagy and Apoptosis.

Temperature is a crucial environmental factor that affects embryonic development, particularly for marine organisms with long embryonic development periods. However, the sensitive period of embryonic development and the role of autophagy/apoptosis in temperature regulation in cephalopods remain unclear. In this study, we cultured embryos of Sepiella japonica, a typical species in the local area of the East China Sea, at different incubation temperatures (18 °C, 23 °C, and 28 °C) to investigate various developmental aspects, including morphological and histological characteristics, mortality rates, the duration of embryonic development, and expression patterns of autophagy-related genes (LC3, BECN1, Inx4) and apoptosis marker genes (Cas3, p53) at 25 developmental stages. Our findings indicate that embryos in the high-temperature (28 °C) group had significantly higher mortality and embryonic malformation rates than those in the low-temperature (18 °C) group. Furthermore, high temperature (28 °C) shortened the duration of embryonic development by 7 days compared to the optimal temperature (23 °C), while low temperature (18 °C) caused a delay of 9 days. Therefore, embryos of S. japonica were more intolerant to high temperatures (28 °C), emphasizing the critical importance of maintaining an appropriate incubation temperature (approximately 23 °C). Additionally, our study observed, for the first time, that the Early blastula, Blastopore closure, and Optic vesicle to Caudal end stages were the most sensitive stages. During these periods, abnormalities in the expression of autophagy-related and apoptosis-related genes were associated with higher rates of mortality and malformations, highlighting the strong correlation and potential interaction between autophagy and apoptosis in embryonic development under varying temperature conditions.

Application of the thermal time model of embryonic development duration to the culture of octopod cephalopods

Data about the effect of temperature on the duration of embryonic development, or the incubation process, are relatively abundant for octopod cephalopods. Experimental data can be used to fit the thermal time classic model of development in order to predict the duration of the process and the range of temperatures within which development proceeds according to the model and with high survival (permissive range), with potential applications for basic research and production activities. The present work is aimed at fitting this classical model to fourteen data sources dealing with eleven species of octopods, seven of them not being previously analyzed, and discussing the constraints and applications of the model. As a result, it is possible to hold that the thermal time model of development duration suitably fits experimental data in octopods, and can be used to schedule hatching events in a production facility. Nevertheless, the range of temperatures tested in the literature is usually too limited to allow an appropriate estimation of the permissive range, so an extension of the temperature range to the known limits of each species is suggested. In addition, when the model is applied to whole spawnings with culture purposes, it is recommended to set the very first hatchings as the criterion for the end of the incubation. Further research is needed to ascertain if temperature fluctuations within and/or out of the permissive range can have implications for the parameterization of the model in octopod species.

Effects of temperature experienced during embryonic development on biomass and C and N composition at hatching in Palaemon serratus (Pennant, 1777)

AbstractIn decapod crustaceans, the conditions experienced during embryonic development trigger phenotypic plasticity of the larvae at hatching. The objective of this study was to test the effects of temperature during embryonic development of Palaemon serratus on the phenotypic plasticity of hatching larvae. We incubated egg‐bearing females from eggs laying to hatching at four temperatures (10, 15, 18 and 20°C). Weight, carbon and nitrogen contents were measured on newly laid eggs and on freshly hatched larvae. The duration of embryonic development was negatively correlated with incubation temperature. At 20°C, all females abandoned their eggs during development. Incubation temperature had no effect on the weight and the percentage of N of the larvae at hatching, while it did affect their percentage of C and their C/N ratio. Embryos incubated at 10°C seemed to produce larvae with fewer lipid reserves than those incubated at 15 and 18°C. They probably overconsumed their lipid reserves to compensate for the metabolic losses due to the low temperature. These results provide information on the link between maternal investment per egg and larval development in P. serratus.

Antheraea peptide and its analog: Their influence on the maturation of the reproductive system, embryogenesis, and early larval development in Tenebrio molitor L. beetle.

In recent years, many new immunologically active peptides from insects have been identified. Unfortunately, in most cases, their physiological functions are not fully known. One example is yamamarin, a pentapeptide isolated from the caterpillars of the Antheraea yamamai moth. This peptide has strong antiproliferative properties and is probably involved in the regulation of diapause. Additionally, antiviral activity was discovered. The results of the research presented in this paper are, to our knowledge, the first attempt to characterize the biological effects of yamamarin on the functioning of the reproductive processes and embryonic development of insects using a model species, the beetle Tenebrio molitor, a commonly known pest of grain storage. Simultaneously, we tested the possible activity of the molecule in an in vivo system. In this research, we present the multifaceted effects of yamamarin in this beetle. We show that yamamarin influences ovarian growth and development, maturation of terminal oocytes, level of vitellogenin gene transcript, the number of laid eggs, duration of embryonic development, and larval hatching. In experiments with palmitic acid-conjugated yamamarin (C16-yamamarin), we also showed that this peptide is a useful starting molecule for the synthesis of biopharmaceuticals or new peptidomimetics with gonadotropic activity and effects on embryonic development. The data obtained additionally provide new knowledge about the possible function of yamamarin in insect physiology, pointing to the important role of this pentapeptide as a regulator of reproductive processes and embryonic development in a heterologous bioassay with T. molitor.

What are the contributions of maternal and paternal traits to fecundity and offspring development? A case study in an amphibian species, the spined toad Bufo spinosus.

Assessing the determinants of reproductive success is critical but often complicated because of complex interactions between parental traits and environmental conditions occurring during several stages of a reproductive event. Here, we used a simplified ecological situation-an amphibian species lacking post-oviposition parental care-and a laboratory approach to investigate the relationships between parental (both maternal and paternal) phenotypes (body size and condition) and reproductive success (fecundity, egg size, embryonic and larval duration, larval and metamorphic morphology). We found significant effects of maternal phenotype on fecundity, hatching success, and tadpole size, as well as on the duration of larval development. Interestingly, and more surprisingly, we also found a potential contribution of the paternal phenotype occurring during early (embryonic development duration) offspring development. Although our study focused on life-history traits such as body size and development duration, additional mechanisms involving physiological costs of development may well mediate the relationships between parental phenotypes and offspring development. Future studies are required to decipher the mechanisms underlying our findings in order to clarify the mechanistic basis of the links between parental phenotypes and offspring development.

Phenology of the 28-spotted potato ladybird beetle <i>Henosepilachna vigintioctomaculata</i> in the south of the Russian Far East

Relevance. The 28-spotted potato ladybird beetle, Henosepilachna vigintioctomaculata, causes severe damage to plants of the Solanaceae family in the south of the Russian Far East. Today the application of chemicals is the main method for protecting crops against the potato ladybird beetle. This leads not only to the eradication of the pest, but also to the pollution of agricultural ecosystems and the emergence of potato ladybird beetle populations that are resistant to pesticides. A study on the seasonal cycles of the development of the potato ladybird beetle may help to devise new methods for controlling this pest.Methods. We conducted laboratory experiments to study the developmental timing ofa potato ladybird beetlepopulation. The number of eggs was counted, and then the eggs were placed in Petri dishes. The number of emerged larvae was recorded on a daily basis. The hatched larvae were transferred to glass containers (hereafter rearing cages) in batches of 10. We recorded the dates of the transition from one immature developmental stage to another notingthe simultaneity of these transitions. At the onset of the pupal stage, the date was recorded and food was withdrawn from the rearing cages. Scientific observations were carried out on the emergence ofyoung beetles. Field research on the phenology of the potato ladybird beetle was conducted at afield site of 40 m2. The timing of the following events was recorded: the emergence of the adult beetles from diapause, the colonization of the potato field, the beginning and the end of oviposition, the emergence of the larvae and the pupae, the flight of the new insect generation.Results and conclusion. Our laboratory experiment on the immature developmental stages of the potato ladybird beetle revealed that the egg stage was 4-5 days in duration, the larval stage was 16-17 days and the pupal stage was 4-5 daysunder optimal conditions. We also observed deviations from the mean values, which could be conditioned by external factors. For instance, the duration of embryonic development depended either on humidity or on the time range of hatching from one egg mass. The observed deviations of the developmental timing of the larvae and the pupae were most probably due to the quantity and quality of the available food, and the presence of secondary metabolites and glycoalkaloids in it. The field research on thephenology of the potato ladybird beetle showed that there was only one generation in 2020, but two generations in 2021. After comparing climatic conditions in 2020 and 2021, we concluded that Henosepilachna vigintioctomaculata can produce two generations during dry and hot years.

Nicosulfuron, a sulfonylurea herbicide, alters embryonic development and oxidative status of hatchlings at environmental concentrations in an amphibian species

The widespread use of agrochemicals for controlling pests and diseases of crops is recognized as a main threat to biodiversity. Sulfonylurea herbicides are being increasingly used and display low levels of degradation in water which suggest that they might affect non-target organisms. In a common garden experiment, eggs of a widespread amphibian (Bufo spinosus) were exposed to sublethal environmentally relevant concentrations of a widely used sulfonylurea herbicide, nicosulfuron, during the whole embryonic development. We assessed development-related traits (i.e., development duration, hatching success, hatchling size and occurrence of malformation) as well as antioxidant markers in response to contamination (i.e., SOD, GPx, catalase, thiols and relevant ratios thereof). We found that sublethal concentrations of nicosulfuron increased embryonic development duration, increased hatchling size and tended to increase malformations. Embryos exposed to nicosulfuron displayed decreased thiols and increased catalase activity suggesting alteration of oxidative status. We did not find any effect of nicosulfuron on SOD and GPx levels. Interestingly, higher catalase activity was linked to higher proportion of malformed individuals, suggesting that exposure to nicosulfuron induced teratogenic effects. Our results suggest that alteration of antioxidant levels might be one physiological mechanism through which nicosulfuron might cause detrimental effects on amphibian embryos. Sublethal effects of pesticides at environmentally relevant concentrations have been overlooked and require further investigations, especially in non-target taxa occurring in agricultural landscapes.

Ten-year outcomes of patients who developed persistent azoospermia following chemotherapy associated with different oncological diagnoses: A retrospective cohort study from a different perspective.

This study evaluated the treatment procedures for chemotherapy (CT)-induced persistent azoospermia and their outcomes from a different perspective. In 63 patients (mean age: 30.16 ± 4.91 years) who had undergone CT 11 ± 5 years earlier, the semen volume, gonadotropins level, FSH level, genetics, micro-testicular sperm extraction (m-TESE) result, sperm DNA fragmentation index (SDFI), semen reactive oxidative stress (ROS) rate, duration of embryonic development, and pregnancy and baby take-home rates were examined. The correlations between the ROS rates and the SDFIs, m-TESE results, sperm motility, pathology scores, time-lapses, and baby take-home rates were evaluated. The semen volumes were 3.5 ± 1.1/ml. The FSH level following CT was 17.87 ± 5.80 mIU/ml. A sperm rate of 34.9% was found from the m-TESE result. The mean SDFI and ROS rate were 4 (<15-30>) and 1.29 ± 0.51, respectively. The time-lapse was calculated as 5h. Pregnancy and live birth were achieved at 20.63% and 12.7%, respectively. In the patients with a low ROS (≤1.42) and SDFI (≤15), the m-TESE success rate was high, the FSH value was low, the pathological score and fertilization rate were elevated, the embryonic cleavage period was normal, and the pregnancy and baby take-home rates were high. The sperms may be detected using m-TESE in patients who develop persistent azoospermia associated with CT due to different oncological diagnoses. Our study revealed that a low FSH value and normal ejaculatory ROS rates are positive predictive factors of sperm detection before m-TESE. The motility of the sperms detected after m-TESE and normal SDFI rates were found to be positive predictive criteria of high fertilization, good embryonic cleavage, pregnancy, and live birth.

Early ontogeny of Clarias gariepinus and its features under artificial cultivation at different temperature conditions

The influence of different temperature regimes (28 ° C and 25 ° C) on the early ontogeny of Clarias gariepinus was studied. Heterochronism in the development of the main systems has been provided: the central nervous system and the digestive system are actively developing, the formation of the cardiovascular, respiratory and genitourinary systems occurs more slowly. The duration of embryonic development within the membranes was 18-22 hours. The initial stages of development changed insignificantly with decreasing temperature. The duration of the larval period was 14 days at 28 ° C and 15 days at 25 ° C. The fry period lasted 30 and 32 days, respectively. In terms of the duration of embryogenesis and the timing of the release of free embryos, the indicators did not go beyond the norm. The percentage of ugly embryos (underdevelopment of the operculum, underdevelopment of the tail, head and fins) was small and amounted to 3.2%, in the first and 4% in the second temperature regime. Incubation at temperatures below the optimum temperature of this species makes it possible to obtain viable offspring, adapted to the change in temperature regime.

Embryonic Development of Grasshopper Populations Along Latitudinal Gradients Reveal Differential Thermoaccumulation for Adaptation to Climate Warming

Climate warming has a remarkable effect on the distribution, phenology, and development of insects. Although the embryonic development and phenology of non-diapause grasshopper species are more susceptible to warming than those of diapause species, the responses of developmental traits in conspecifically different populations to climate warming remain unknown. Here, we compared the mtDNA sequences and embryonic development of eight populations of grasshopper species (Chorthippus dubius) in field-based manipulated warming and laboratory experiments. The mtDNA sequences showed a significant genetic differentiation of the southernmost population from the other seven populations on the Mongolian Plateau. The embryonic development of the southernmost population was significantly slower than those of the northern populations at the same incubation temperatures. Interestingly, laboratory experiments showed that a significant difference exists in the effective accumulated degree days (EADD) but not in the lower development threshold temperatures (LDTT) among the different populations. The high-latitude populations required less EADD than the low-latitude populations. The warming treatments significantly accelerated the embryonic development in the field and decreased duration from embryos to hatchlings of all eight populations in the incubation. In addition, warming treatments in field significantly increased EADD requirement per stage in the incubation. Linear regression model confirmed that the embryonic development characteristics of eight populations were correlated with the annual mean temperature and total precipitation of embryonic development duration. The results indicated that grasshopper species have evolved a strategy of adjusting their EADD but not their LDTT to adapt to temperature changes. The variations in the EADD among the different populations enabled the grasshopper eggs to buffer the influences of higher temperatures on development and preserve their univoltine nature in temperate regions while encountering warmer climatic conditions. Thus, the findings of this study is valuable for our understanding species variation and evolution, and as such has direct implication for modeling biological response to climate warming.

Lethal and sub-lethal effects of garlic extracts on females and eggs of Tetranychus urticae Koch (Tetranychidae)

Two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important polyphagous pest on a wide range of cultivated, outdoor and protected crops worldwide. In this study, lethal and sub-lethal effects of garlic, Allium sativum Linnaeus extracts on the females and eggs of T. urticae was evaluated in laboratory conditions. The results showed that the mortality percentages of the females of T. urticae were significantly increased in the treated specimens compared with the controls in garlic ethanol extract treatment (88.52 ± 3.45%). Moreover, in the highest and lowest duration of embryonic development were recorded in ethanol with 6.09 ± 0.03 and acetic acid with 3.87 ± 0.07 days, respectively. Generally, the garlic extract had the appreciable effect from the viewpoint of mortality and sub-lethal effect (reduction of the oviposition). With carrying out further complimentary research these botanical compounds can be used in integrated pest management.

Aminomethylphosphonic acid (AMPA) alters oxidative status during embryonic development in an amphibian species

Glyphosate's primary metabolite (aminomethylphosphonic acid, AMPA) is known to alter embryonic development at environmentally relevant concentrations in amphibians. However, we have limited understanding of the physiological mechanisms through which AMPA affects organisms. In this study, we tested whether alteration of the oxidative status is one mechanism through which AMPA affects organism performance. To this end, we analysed several oxidative status markers in hatchling tadpoles that were exposed to sublethal concentrations of AMPA during embryonic development (~16 days). We compared the influence of environmentally relevant concentrations of AMPA (from 0.07 to 3.57 μg l−1) on the relation between developmental traits (i.e, embryonic development duration, embryonic mortality and hatchling size) and oxidative status markers known to alter homeostasis when unbalanced (superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), thiols and ratios thereof). We included measures of telomere length as an indicator of physiological state. We found that AMPA concentrations induce non-monotonic effects on some oxidative status markers with hatchlings displaying elevated antioxidant responses (elevated thiols and unbalanced SOD/(GPx + CAT) ratio). The lack of effect of AMPA on the relation between developmental traits, oxidative status and telomere length suggests that selective mortality of embryos susceptible to oxidative stress may have occurred prior to hatching in individuals less resistant to AMPA which display lower hatching success. Future studies are required to disentangle whether oxidative unbalance is a cause or a consequence of AMPA exposition. This study highlights the need to investigate effects of the metabolites of contaminants at environmental concentrations to comprehensively assess impacts of anthropogenic contamination on wildlife.

Clutch quality is related to embryonic development duration, hatchling body size and telomere length in the spined toad (Bufo spinosus)

AbstractReproductive success is often related to parental quality, a parameter expressed through various traits, such as site selection, mate selection and energetic investment in the eggs or progeny. Owing to the complex interactions between environmental and parental characteristics occurring at various stages of the reproductive event, it is often complicated to tease apart the relative contributions of these different factors to reproductive success. Study systems where these complex interactions are simplified (e.g. absence of parental care) can help us to understand how metrics of parental quality (e.g. gamete and egg quality) influence reproductive success. Using such a study system in a common garden experiment, we investigated the relationships between clutch hatching success (a proxy of clutch quality) and offspring quality in an amphibian species lacking post-oviposition parental care. We found a relationship between clutch quality and embryonic development duration and hatchling phenotype. We found that hatchling telomere length was linked to hatching success. These results suggest that clutch quality is linked to early life traits in larval amphibians and that deciphering the influence of parental traits on the patterns we detected is a promising avenue of research.

Does parental heart rate affect embryonic heart rate during incubation? An experiment in Common Terns Sterna hirundo

Embryonic heart rate is a strong determinant of metabolic rate and the rate of embryonic development in oviparous species. In humans, embryonic heart rate is positively correlated with the heart rate of the mother. However, human embryos do not develop autonomously from the maternal circulatory system, making it impossible to separate maternal control from an independent embryonic adjustment of its heart rate to that of its mother. In birds, embryonic development does occur autonomously from the mother, while the embryo can auditively perceive the heart rate of the incubating parent. In this study, we used Common Terns (Sterna hirundo) to experimentally test whether the embryonic heart rate is affected by parental heart rate during incubation. We artificially incubated freshly laid eggs under standardized conditions and continuously exposed them to the sound of either a slow or fast parental heart rate throughout the first 18 days of embryonic development. At day 18 of embryonic development (a few days before hatching) there was no significant difference in the embryonic heart rate between both treatments. There was also no effect of treatment on either total duration of embryonic development or hatching success. We suggest that embryonic heart rate and development rate may not be affected by the heart rate of the parent because natural parental heart rates are very sensitive to external conditions that may fluctuate drastically, while embryos may need a relatively stable heart rate for optimal development.

Reproductive performance of Macrobrachium acanthurus (Crustacea, Palaemonidae) females subjected to unilateral eyestalk ablation

AbstractThe present study investigated the effects of eyestalk ablation on the reproductive performance of females from the native caridean shrimp Macrobrachium acanthurus. The reproduction parameters fertility, fecundity, egg volume, larvae size, loss of embryos and number of females with viable eggs/larvae were evaluated. Females presenting carapace length of 12–15 mm and spent stage of gonadal development were divided into two groups, one undergoing unilateral eyestalk ablation and the other remaining intact. The specimens were kept in aquarium until ovarian maturation, then brought together with males for mating (proportion of two females for each male). Fecundity and fertility were greater in intact females (1,741 eggs and 1,045 larvae) than in ablated ones (1,373 eggs and 741 larvae). Ablation also reduced the percentage of females with viable eggs (68% intact versus 49% ablated) and larvae (82% intact versus 64% ablated), besides increasing the loss of embryos. Egg volume and shape (ellipsoid) and larvae size were similar, as was the duration of embryonic development. The results of this study suggest that, although ablated females exhibit a high rate of survival, their reproductive performance is reduced; therefore, the ablation technique is not recommended in M. acanthurus farming, so as to protect the animals from physiological stress.

Effects of moisture during incubation on green sea turtle (Chelonia mydas) development, morphology and performance

While the effect of temperature on embryonic development in sea turtles has been well studied over recent years, our understanding of the effect of substrate moisture, another important environmental variable, is limited. High sand moisture decreases nest temperature through evaporative and direct cooling during rainfall, but its direct effect on hatchling development, morphology and performance is unclear. To address this knowledge gap, we incubated 40 green sea turtle Chelonia mydas clutches in a beach hatchery under either high (~8% v/v) or low (~5% v/v) sand moisture concentrations for the duration of embryonic development. In half of the clutches, temperature sensors were deployed to measure any effect of sand moisture on nest temperature. As hatchlings emerged, we measured body size and locomotory performance during the first 24 h, an important period of frenzied activity for sea turtles. We excavated clutches post-emergence to determine hatching success, emergence success and to determine the stage of embryonic death for unsuccessful eggs. High moisture concentrations increased incubation duration, decreased nest temperature and had marginal effects on hatchling morphology, but no effect on hatching success, stage of embryonic death, crawling speed or initial swimming performance. However, after 24 h of swimming, hatchlings from high-moisture clutches produced less mean swim thrust and spent less time powerstroking than hatchlings from low-moisture clutches, suggesting reduced swimming endurance and potentially impacting the ability of hatchlings to successfully disperse. The effect of moisture on nest temperature and hatchling endurance highlights the importance of considering rainfall patterns when predicting future impacts of climate change on sea turtle populations.

HEMATOLOGICAL INDICES AND THE RATE OF GROWTH DEPENDING ON DURATION OF EMBRYONIC GROWTH OF PIGS OBTAINED BY COMMERCIAL CROSS-BREEDING

The studies were performed in pigs obtained by commercial cross-breeding under conditions of pig-breeding complex of Agricultural Open Joint-Stock Company Agrokombinat Kalyta. 115 crossbred breeding sows (Big White x Landras) – of similar age and development – were selected for the study; they were mated with purebred Big White boars. Three groups by five animals were selected from these breeding sows by pregnancy duration. The first one (control group, the pregnancy duration was the farm average) – 112-116 days; the second one (study group, reduced pregnancy duration) – 103-111 days; the third one (study group, extended pregnancy duration) – 117-120 days. The authors studied the growth duration and hematological parameters of these breeding sows’ offsprings after ablactation until the end of fattening. The piglets were ablactated at the age of 26 days. The young stock were fed with dry feed stuff according to the conventional technology. The feed level for the pigs of all groups was the same. The pigs were weighted upon birth at 1, 2, 4, 6 months, and the relative weight gain and actual growth rate of the pigs were determined by Shmalgauzen and Brody formula. Hematological tests were performed at the age of 2, 4 and 6 months in four animals from each group (two gilts and two boars). Blood for tests was collected from auricular veins before feeding. Red blood cell count and hemoglobin concentration were measured by hemascope, total protein, albumin and globulins were measured refractometrically. It has been established that the piglets obtained from the breeding sows with reduced pregnancy duration had the lowest body weight at birth, and the piglets obtained from the extended pregnancy had the highest body weight. From the age of two months, the young stock with the reduced embryonic growth duration were superior to the age-mates with the average and extended pregnancy in terms of body weight. The animals with reduced embryonic growth duration had higher relative weight gain and the actual growth rate factor, which characterizes their high growth intensity. The pigs obtained at commercial cross-breeding with different embryonic development duration had different blood composition. Thus, the piglets with reduced and average embryonic growth duration, had higher red blood cells count, hemoglobin and total protein content. Higher hematological indicators in pigs with reduced embryonic period coincide with the period of their higher growth energy which indicates the interrelation between the intensity of the animals’ growth and the red blood cell count, hemoglobin and total protein in blood. Therefore, the embryonic development period reduction positively affects the growth energy, that is associated with improved hematological indicators, which is advisable to consider in pigs selection program.

Keeping, Breeding, and Maintenance of Zooculture of the Ladakh Toad, &lt;i&gt;Bufotes latastii&lt;/i&gt; (Boulenger, 1882)

In this paper we present results of laboratory reproduction of the Ladakh toad (Bufotes latastii) for three generations. Two pairs of animals, which were collected in April of 2013 in Jammu and Kashmir (India), became founders of a laboratory population. The first female gave offspring four times, while the second only once. The number of eggs in clutches obtained from the first female was 6804 – 10149 and from the second was 4080 eggs. Males, which were born in laboratory, started to vocalize at the age of 3 – 4 months after metamorphosis and at the age of one year successfully reproduced. Females become mature at the two-year age only. Thus, B. latastii is a fast-growing and early-maturing species. The number of eggs in clutches of 2-year-old laboratory females ranged from 31 to 6420 eggs (n = 28) and 3-year-old females from 19 to 6859 eggs (n = 21). Clutches were single- or double-row strings. The average thickness of egg strings was 3.2 – 5.9 mm. The diameter of eggs was 0.8 – 1.9 mm. The duration of embryonic development (until separation of pre-larvae from egg strings) was 2 – 5 days. The total body length of pre-larvae was 2.0 – 4.3 mm. The first larvae that started swimming and feeding were observed within 2 – 3 days after separation of pre-larvae from egg strings. The body length of larvae at the time of start of exogenous feeding was 2.9 – 4.3 mm and the length of tail was 1.6 – 6.3 mm. The total duration of embryogenesis was 4 – 8 days, larval development was 86 – 125 days, and overall development was 90 – 127 days.

Особенности развития клариевого сома (Clarias gariepinus, Burchell, 1822) в раннем онтогенезе

The article presents a research of the features of embryonic development of clarid catfish (Clarias gariepinus (Burchell, 1822)) conducted at the Southern Scientific Centre of the Russian Academy of Sciences in the period 2016-2019, as well as at the Department of aquaculture and fisheries of Astrakhan State Technical University. The aim of research is to analyze the duration of embryonic development of the clarid catfish (Clarias gariepinus, Burchell, 1822) in early ontogenesis during artificial reproduction, as well as to study changes in the rate of development of clarid catfish at different temperatures and changes in temperature regime. When analyzing the influence of temperature on the embrional development it was found that duration of the initial stages of development changes slightly and the decrease rates of embryogenesis due to a decrease in temperature corresponds to the late stages of the embryo growth, which can be explained by the adaptation to hatching in the most favorable conditions. A description of embryonic development and growth of catfish embryos and pre-larvae is given. During embryogenesis, morphological features that are easily identified and reflect the process of morphogenesis are identified. It has been found that the duration of embryogenesis of clarid catfish, as well as its individual stages, increases with a decreasing water temperature. As a result of the research, it has been inferred that the duration of embryonic development inside the shells is 18-22 hours. The results of observations on the behavior and morphogenesis of pre-larval clarid catfish kept in an artificially formed system are analyzed