- Development and regulation of breathing rhythms in embryonic and hatchling birds. [Review]
- RPRespir Physiol Neurobiol 2019 Jul 05
- For many, if not all, air-breathing vertebrates, breathing-like movements begin while the embryo is still ensconced in an aqueous environment. This is because primordial regions of the CNS become spo…
For many, if not all, air-breathing vertebrates, breathing-like movements begin while the embryo is still ensconced in an aqueous environment. This is because primordial regions of the CNS become spontaneously active during early gestation and then must functionally transform and specialize once air breathing commences. The degree to which the embryonic ventilatory control system is established and competent at birth is variable, however, even between different components of the respiratory system. Moreover, the embryological experiences of an individual can also affect the outcomes and responsiveness of ventilation to respiratory stimuli and these details have major clinical implications. The broad field of respiratory neurobiology still has much to learn about the ontogeny of breathing control systems, and the oviparity of birds provides a unique model to examine how early rhythms transform day-to-day as they become functional. This hybrid review and research article will highlight the contributions of birds to the study of breathing control during early development. We will detail what is currently known about the onset and maturation of respiratory rhythm generation and also provide novel data about the development of central chemosensitivity. Finally, we will review data regarding the development of peripheral afferent inputs during early development and discuss whole-animal reflex responsiveness to common respiratory stimuli, both chronic and acute, during the incubation period and following hatching.
- Effects of selenium on benthic macroinvertebrates and fathead minnow (Pimephales promelas) in a boreal lake ecosystem. [Journal Article]
- EEEcotoxicol Environ Saf 2019 Jul 01; 182:109354
- Selenium (Se) is a contaminant of concern in many aquatic ecosystems due to its narrow range between essentiality and toxicity in oviparous (yolk-bearing) vertebrates. The objective of the present st…
Selenium (Se) is a contaminant of concern in many aquatic ecosystems due to its narrow range between essentiality and toxicity in oviparous (yolk-bearing) vertebrates. The objective of the present study was to determine the effects of Se, experimentally added to in situ limnocorrals as selenite, on invertebrate communities and fathead minnow (Pimephales promelas) at environmentally realistic Se concentrations. Nine limnocorrals were deployed in a mesotrophic lake at the International Institute for Sustainable Development - Experimental Lakes Area in Ontario, Canada in May 2017. From June 1 to August 17, 2017, selenite was added to six enclosures to attain mean measured aqueous Se concentrations of 1.0 ± 0.10 or 8.9 ± 2.7 μg/L Se (in triplicate) and three limnocorrals were untreated controls (background mean aqueous Se = 0.12 ± 0.03 μg/L). Benthic macroinvertebrates were collected throughout and at the end of the exposure period using artificial substrates to determine density, dry biomass, diversity, and taxa richness at the family level. Reproductively mature female fathead minnows (added on d 33 of the study) were collected throughout and at the end of the exposure period. After 77 d, Chironomidae and Gammaridae densities and biomass were significantly lower in the 8.9 μg/L Se treatment relative to the 1.0 μg/L Se treatment and the control. Invertebrate diversity (measured as Shannon's and Simpson's indices) significantly declined in the 1.0 μg/L and 8.9 μg/L Se treatments relative to the control (0.12 μg/L Se group). Fulton's condition factor for fathead minnow was significantly less in the 8.9 μg/L treatment compared to 0.12 and 1.0 μg/L Se experimental groups. The results of this study indicated that exposure to relatively low aqueous selenite concentrations can negatively affect invertebrate density and biomass, as well as fish condition. More research is necessary to characterize the risk of selenite exposure to aquatic invertebrates under realistic field conditions, and future risk assessments may need to consider reduced food availability as a factor that may impair the health of higher trophic level organisms in areas with elevated selenite.
- Energy budget of Drosophila embryogenesis. [Letter]
- CBCurr Biol 2019 Jun 17; 29(12):R566-R567
- Eggs of oviparous animals must be prepared to develop rapidly and robustly until hatching. The balance between sugars, fats, and other macromolecules must therefore be carefully considered when loadi…
Eggs of oviparous animals must be prepared to develop rapidly and robustly until hatching. The balance between sugars, fats, and other macromolecules must therefore be carefully considered when loading the egg with nutrients. Clearly, packing too much or too little fuel would lead to suboptimal conditions for development. While many studies have measured the overall energy utilization of embryos, little is known of the identity of the molecular-level processes that contribute to the energy budget in the first place . Here, we introduce Drosophila embryos as a platform to study the energy budget of embryogenesis. We demonstrate through three orthogonal measurements - respiration, calorimetry, and biochemical assays - that Drosophila melanogaster embryogenesis utilizes 10 mJ of energy generated by the oxidation of the maternal glycogen and triacylglycerol (TAG) stores (Figure 1). Normalized for mass, this is comparable to the resting metabolic rates of insects . Interestingly, alongside data from earlier studies, our results imply that protein, RNA, and DNA polymerization require less than 10% of the total ATPs produced in the early embryo.
- Gestation alters the gut microbiota of an oviparous lizard. [Journal Article]
- FMFEMS Microbiol Ecol 2019 Jul 01; 95(7)
- Mammalian pregnancy can alter the diversity, membership and structure of the maternal gut microbiota, but it is unclear whether this phenomenon occurs in vertebrates with different reproductive strat…
Mammalian pregnancy can alter the diversity, membership and structure of the maternal gut microbiota, but it is unclear whether this phenomenon occurs in vertebrates with different reproductive strategies. We conducted 16S rRNA bacterial inventories to investigate whether oviparous lizards exhibit shifts in gut microbiota similar to those observed in mammals. Using wild-caught eastern fence lizards from Alabama, USA, we collected and extracted fecal DNA from gravid and non-gravid individuals over 54 days in captivity. We predicted that, like mammals, the alpha diversity of lizard gut microbiota would decrease over gestation, and that inter-individual variation in community composition would increase. Indeed, we found that individuals in late-gestation harbored lower gut bacterial richness compared to non-gravid females. Lizard gut microbial communities of late-gestational females exhibited higher pairwise distances for both community membership and community structure compared to earlier gestation stages, indicating a higher degree of inter-individual variation as gestation progressed. Additionally, we found that the relative abundance and prevalence of the candidate phylum Melainabacteria tended to decrease over the course of gestation. While the consequences of these specific alterations are unknown, our results suggest that a general restructuring of gut microbial communities over gestation may be widespread across vertebrate reproductive strategies.
- How do actinyls interact with hyperphosphorylated yolk protein phosvitin? [Journal Article]
- CChemistry 2019 Jun 17
- The development of nuclear industries has raised multiple questions about its impact on the biotope and humans. Proteins are key biomolecules in cell machinery and essential actors in deciphering tox…
The development of nuclear industries has raised multiple questions about its impact on the biotope and humans. Proteins are key biomolecules in cell machinery and essential actors in deciphering toxicological processes. Phosvitin was chosen as a relevant model for phosphorylated proteins and because of its important role as an iron, calcium, and magnesium storage protein in egg yolk. Here we carried out a multi-technique spectroscopic investigation in order to reveal the coordination geometry of two oxocations of the actinide family (actinyl U(VI), Np(V)) in speciation with phosvitin. Infrared spectroscopy revealed phosphoryl groups as the main functional groups interacting with U(VI). This was confirmed through laser luminescence spectroscopy (U) and UV-Vis absorption spectroscopy (Np). X-ray Absorption Spectroscopy at LIII edge revealed for U(VI) a small contribution of bidentate binding present along with predominantly monodentate binding of phosphoryl groups and for Np(V) uniquely bidentate binding. As a perspective to this work, XAS speciation of U(VI) and Np(V) in the extracted yolk of the living eggs of Dogfish Scyliorhinus canicula was determined, which corroborates the binding of phosphorous together with a reduction process of the actinyl moiety. Such data are essential to pinpoint the mechanisms of heavy metals (actinyls) accumulation and toxicity in oviparous organisms and therefore, contribute to shift from descriptive approaches to predictive toxicology.
- Development of scleral ossicles in Podocnemis expansa (Testudines: Podocnemididae) embryos exposed to atrazine. [Journal Article]
- DCDrug Chem Toxicol 2019 Jun 14; :1-6
- Understanding the effects of atrazine exposure on embryo development in oviparous animals may provide important data regarding the impacts of agrochemical use on wildlife and the ecosystem. This stud…
Understanding the effects of atrazine exposure on embryo development in oviparous animals may provide important data regarding the impacts of agrochemical use on wildlife and the ecosystem. This study set out to determine the effects of embryonic atrazine exposure on the development of osseous and cartilaginous components of scleral ossicles in Podocnemis expansa. Eggs were collected at the Environmental Protection Area Meandros do Rio Araguaia, Brazil, and artificially incubated in sand treated with solutions containing 2, 20 or 200 µg/L of atrazine. Sixty embryos were collected per treatment throughout the incubation period. Embryos were diaphanized with potassium hydroxide (KOH) and stained with Alizarin Red S and Alcian blue (bone and cartilage tissue respectively). Scleral ossicles were then counted and examined for skeletal abnormalities at different stages of embryonic development. Scleral ossicle counts were significantly reduced in P. expansa embryos treated with 200 μg/L atrazine solution. Rudimentary ossicles and gaps were also noted in embryos exposed to atrazine concentrations of 2 μg/L or 200 μg/L. Findings of this study emphasize the relevance of ecotoxicological investigations in determining the impacts of agrochemicals on native fauna.
- Climate change will decrease the range size of snake species under negligible protection in the Brazilian Atlantic Forest hotspot. [Journal Article]
- SRSci Rep 2019 Jun 12; 9(1):8523
- Reptiles are highly susceptible to climate change, responding negatively to thermal and rainfall alterations mainly in relation to their reproductive processes. Based on that, we evaluated the effect…
Reptiles are highly susceptible to climate change, responding negatively to thermal and rainfall alterations mainly in relation to their reproductive processes. Based on that, we evaluated the effects of climate change on climatically suitable areas for the occurrence of snakes in the Atlantic Forest hotspot, considering the responses of distinct reproductive groups (oviparous and viviparous). We assessed the species richness and turnover patterns affected by climate change and projected the threat status of each snake species at the end of the century. We also evaluated the effectiveness of the protected areas in safeguarding the species by estimating the mean percentage overlap between snake species distribution and protected areas (PAs) network and by assessing whether such areas will gain or lose species under climate change. Our results showed greater species richness in the eastern-central portion of the Atlantic Forest at present. In general, we evidenced a drastic range contraction of the snake species under climate change. Temporal turnover tends to be high in the western and north-eastern edges of the biome, particularly for oviparous species. Our predictions indicate that 73.6% of oviparous species and 67.6% of viviparous species could lose at least half of their original range by 2080. We also found that existing protected areas of the Atlantic Forest Hotspot have a very limited capacity to safeguard snakes at the current time, maintaining the precarious protection in the future, with the majority of them predicted to lose species at the end of this century. Although oviparous and viviparous snakes have been designated to be dramatically impacted, our study suggests a greater fragility of the former in the face of climate change. We advocated that the creation of new protected areas and/or the redesign of the existing network to harbour regions that maximize the snake species occupancy in the face of future warming scenarios are crucial measures for the conservation of this group.
- Evidence for cell turnover as the mechanism responsible for the transport of embryos towards the vagina in viviparous onychophorans (velvet worms). [Journal Article]
- FZFront Zool 2019; 16:16
- CONCLUSIONS: Our results confirm the hypothesis that the uterus of placentotrophic onychophorans grows proximally but is resorbed distally. This is supported by the detection of a proximal proliferation zone and a distal degenerative zone in the two placentotrophic species. Hence, cell turnover might be responsible for the transport of their embryos towards the vagina, analogous to a conveyor belt. Surprisingly, the distal degenerative zone is also found in the non-placentotrophic species, in which cell turnover was unexpected. These findings suggest that the distal degenerative zone is an ancestral feature of Onychophora, whereas the proximal proliferation zone might have evolved in the last common ancestor of the placentotrophic Peripatidae.
- Vitellogenin in the European cave salamander, Proteus anguinus: Its characterization and dynamics in a captive female as a basis for non-destructive sex identification. [Journal Article]
- CBComp Biochem Physiol B Biochem Mol Biol 2019; 235:30-37
- Vitellogenin (Vtg) is a precursor protein of egg yolk proteins in oviparous and ovoviviparous vertebrates. Except in a case of exposure to estrogenic endocrine disruptors, Vtg is a female-specific pr…
Vitellogenin (Vtg) is a precursor protein of egg yolk proteins in oviparous and ovoviviparous vertebrates. Except in a case of exposure to estrogenic endocrine disruptors, Vtg is a female-specific protein and could be used as a molecular marker for sex identification. This would be especially useful in the case of the endangered European cave salamander Proteus anguinus in which sexes are indistinguishable according to external morphology, which hinders the establishment of a successful captive breeding program. Here we describe the identification, partial characterization, and purification of Vtg from P. anguinus. Vtg was identified in the plasma of a vitellogenic proteus female with visible oocytes. The identification of this protein was accomplished by mass spectrometry analysis. Two-dimensional gel electrophoresis revealed proteus Vtg as a mix of 190 kDa isoforms with isoelectric points in the pH range 5.3-6.0. Vtg was purified from proteus blood by gel filtration followed by anion-exchange chromatography. Using specific staining of SDS-PAGE gels, the Vtg was found to be phosphorylated and lipidated. Unlike the case in some other aquatic vertebrates, in P. anguinus, Vtg was not present in detectable amounts in cutaneous mucus. Degradation of oocytes in the captive vitellogenic female was accompanied by simultaneous decrease of Vtg concentration. Over a period of 10 months, the concentration of Vtg dropped from maximal to sub-detectable. Our results show that Vtg is a promising molecular marker for sex identification and ovary maturation in P. anguinus, which could contribute to the development of a viable program for captive reproduction of this unique species.
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- Egg incubation temperature influences the growth and foraging behaviour of juvenile lizards. [Journal Article]
- BPBehav Processes 2019; 165:9-13
- After laying their eggs, oviparous reptiles are reliant on the external environment to provide the required incubation conditions for successful embryonic development. Egg incubation temperature can …
After laying their eggs, oviparous reptiles are reliant on the external environment to provide the required incubation conditions for successful embryonic development. Egg incubation temperature can impact the behaviour of various species of reptiles, but previous experiments have focused on the impact of incubation environment on hatchlings, with only a limited number of studies focussing on the longer-term behavioural consequences of incubation environment. This study investigated the effects of developmental environment on bearded dragon lizards (Pogona vitticeps) that were incubated at different temperatures within the natural range; half of them were incubated at a 'hot' temperature (30 ± 3 °C) and half at a 'cold' temperature (27 ± 3 °C). The growth and foraging behaviour of the lizards was then compared over 18 weeks of development. Although the lizards incubated at a cool temperatures grew more quickly, those incubated at the hotter temperature completed the foraging task more often and had significantly faster running speeds. These results show that egg incubation temperature impacts the foraging behaviour of juvenile lizards and suggest a potential trade-off between growth and foraging speed, which could influence an animal's life history trajectory.