Zoology最新文献

Reproductive specializations in caviomorphs (infraorder Hystricognathi), are very peculiar within the Order Rodentia. These include long gestations, the birth of offspring with an extreme degree of precociality, and short lactation periods. This study describes the embryo-placental relationship of viable implantation sites (IS) of the plains viscacha, Lagostomus maximus, after 46 post-coital days. The observations recorded in this study are comparatively discussed with those of other hystricognaths and eutherians. At this stage, the embryo resembles that of other eutherians. At this time of embryo development, the placenta exhibits a size, shape, and organization similar to that it will have in its mature state. Besides, the subplacenta is already highly folded. These characteristics are adequate to sustain the development of future precocial offspring. The mesoplacenta, a structure present in other hystricognaths and related to uterine regeneration is described for the first time in this species. This detailed description of the placental and embryonic structure contributes to the knowledge of the reproductive and developmental biology of the viscacha, as well as that of hystricognaths. These characteristics will allow testing other hypotheses related to the morphology and physiology of the placenta and subplacenta, and their relationship with the growth and development of precocial offspring in Hystricognathi.

The Common Wasp, Vespula vulgaris (Hymenoptera: Vespidae), has an annual nest cycle with new colonies initiated by over-wintered queens. Survival of adult queen wasps through winter dormancy is enabled through the deposition of substantial quantities of triglycerides in fat bodies. Worker (and male) wasps lack these fat reserves. By comparing micro-CT scans of workers, pre-hibernation queens and post-hibernation queens, we demonstrate that it is possible to semi-quantitatively measure fat reserves using arbitrary X-ray attenuation ranges. Venom in the venom gland of the queen wasps, has a significantly lower X-ray attenuation value than the triglyceride-rich fat bodies. This may be due to its content of low molecular weight volatile pheromones in addition to its other known constituents. We also demonstrate the utility of micro-CT for visualising a range of physiological and anatomical features of insects. This non-destructive method for measuring fat reserves can be used on appropriately preserved or freshly collected insect specimens.

There is a gap in our knowledge of microorganization and the functioning of ovaries in earthworms (Crassiclitellata) and allied taxa. Recent analyses of ovaries in microdriles and leech-like taxa revealed that they are composed of syncytial germline cysts accompanied by somatic cells. Although the pattern of cyst organization is conserved across Clitellata – each cell is connected via one intercellular bridge (ring canal) to the central and anuclear cytoplasmic mass termed the cytophore – this system shows high evolutionary plasticity. In Crassiclitellata, only the gross morphology of ovaries and their segmental localization is well known, whereas ultrastructural data are limited to lumbricids like Dendrobaena veneta. Here we present the first report about ovarian histology and ultrastructure in Hormogastridae, a small family of earthworms inhabiting the western parts of the Mediterranean sea basin. We analyzed three species from three different genera and showed that the pattern of ovary organization is the same within this taxon. Ovaries are cone-like, with a broad part connected to the septum and a narrow distal end forming an egg string. Ovaries are composed of numerous cysts uniting a small number of cells, eight in Carpetania matritensis. There is a gradient of cysts development along the long ovary axis, and three zones can be distinguished. In zone I, cysts develop in complete synchrony and unite oogonia and early meiotic cells (till diplotene). Then (zone II), the synchrony is lost, and one cell (prospective oocyte) grows faster than the rest (prospective nurse cells). In zone III, oocytes pass the growth phase and gather nutrients; at this time, their contact with the cytophore is lost. Nurse cells grow slightly, eventually die via apoptosis, and are removed by coelomocytes. The most characteristic feature of hormogastrid germ cysts is the inconspicuous cytophore in the form of thread-like thin cytoplasmic strands (reticular cytophore). We found that the ovary organization in studied hormogastrids is very similar to that described for D. veneta and propose the term "Dendrobaena" type of ovaries. We expect the same microorganization of ovaries will be found in other hormogastrids and lumbricids.

Gastropods of the superfamily Conoidea are present in high diversity in the oceans and are characterized by having modified foregut anatomy and radular morphology. This study provides details on variations in the radula teeth of the species Hastula cinerea, which have hypodermic radula teeth of the toxoglossan type and are part of the Terebridae family – inserted in the Conoidea superfamily. Hastula cinerea specimens were collected at Flecheiras beach, Trairi, Ceará, Brazil. Scanning Electron Microscopy (SEM) was performed to analyse the radula specificities. Thirty specimens were used between females and males, with different sizes. The total length of the shell and the length of the teeth of all analysed specimens were measured. With the SEM result, more than one radula tooth morphotype was found for the species H. cinerea. The pattern of the teeth found is similar to the hypodermic teeth of the group, however, with structural and length differences between smaller and larger individuals. It was possible to observe three radula variations (morphotype-1, morphotype-2 and morphotype-3), 26 related to different sizes of individuals, regardless of sex, configuring a variation in the radula teeth. Therefore, this result brings a contribution that stimulates future research with the functional morphology of H. cinerea and others auger snails.

Microbial communities inhabiting sponges are known to take part in many metabolic pathways, including nutrient cycles, and possibly also in the bioaccumulation of trace elements (TEs). Here, we used high-throughput, Illumina sequencing of 16S rRNA genes to characterize the prokaryotic communities present in the cortex and choanosome, respectively the external and internal body region of Chondrosia reniformis, and in the surrounding seawater. Furthermore, we estimated the total mercury content (THg) in these body regions of the sponge and in the corresponding microbial cell pellets. Fifteen prokaryotic phyla were detected in association with C. reniformis, 13 belonging to the domain Bacteria and two to the Archaea. No significant differences between the prokaryotic community composition of the two regions were found. Three lineages of ammonium-oxidizing organisms (Cenarchaeum symbiosum, Nitrosopumilus maritimus, and Nitrosococcus sp.) co-dominated the prokaryotic community, suggesting ammonium oxidation/nitrification as a key metabolic pathway within the microbiome of C. reniformis. In the sponge fractions, higher THg levels were found in the choanosome compared to the cortex. In contrast, comparable THg levels found in the microbial pellets obtained from both regions were significantly lower than those observed in the corresponding sponge fractions. Our work provides new insights into the prokaryotic communities and TEs distribution in different body parts of a model organism relevant for marine conservation and biotechnology. In this sense, this study paves the way for scientists to deepen the possible application of sponges not only as bioindicators, but also as bioremediation tools of metal polluted environments.

Claws are a common anatomical feature among limbed amniotes and contribute to a variety of functions including prey capture, locomotion, and attachment. Previous studies of both avian and non-avian reptiles have found correlations between habitat use and claw morphology, suggesting that variation in claw shape permits effective functioning in different microhabitats. How, or if, claw morphology influences attachment performance, particularly in isolation from the rest of the digit, has received little attention. To examine the effects of claw shape on frictional interactions, we isolated the claws of preserved specimens of Cuban knight anoles (Anolis equestris), quantified variation in claw morphology via geometric morphometrics, and measured friction on four different substrates that varied in surface roughness. We found that multiple aspects of claw shape influence frictional interactions, but only on substrates for which asperities are large enough to permit mechanical interlocking with the claw. On such substrates, the diameter of the claw’s tip is the most important predictor of friction, with narrower claw tips inducing greater frictional interactions than wider ones. We also found that claw curvature, length, and depth influence friction, but that these relationships depend on the substrate’s surface roughness. Our findings suggest that although claw shape plays a critical role in the effective clinging ability of lizards, its relative importance is dependent upon the substrate. Description of mechanical function, as well as ecological function, is critical for a holistic understanding of claw shape variation.

Every year, more and more discoveries of photoluminescence in different mammal species are made. The more recent cases thus far have been in duck-billed platypus (Ornithorhyncus anatinus), New World squirrels (Glaucomys spp.) and springhare (Pedetidae). Now we can add another species to the list: the garden dormouse (Eliomys quercinus), an endemic rodent to Europe, currently categorized as Near Threatened (NT) by the IUCN. The fluorescence was described and compared qualitatively in museum specimens, deceased and hibernating animals. The feet and nose of the hibernating dormouse displayed greenish-blue photoluminescence under UV light through a yellow filter, whereas the fur was bright red. The live animal had more vivid red colouring than the museum specimen. The fading and changing of the colour and brightness of photoluminescence was observed in a recently deceased animal and even more strongly in museum specimens.

Shark intestine presents a complicated three-dimensional morphology, characterized by the development of a coiled internal septum. A basic question regarding the intestine is its movement. This lack of knowledge has prevented the testing of the hypothesis on its functional morphology. The present study, to our knowledge, for the first time, visualized the intestinal movement of three captive sharks using an “underwater ultrasound” system. The results indicated that the movement of the shark intestine involved strong twisting. We suspect that this motion is the mechanism that tightens the coiling of the internal septum, enhancing compression of the intestinal lumen. Our data also revealed the presence of active undulatory movement of the internal septum, of which the undulatory wave propagated in the opposite (anal-to-oral) direction. We hypothesize that this motion decreases the flow rate of the digesta and increases absorptive time. These observations indicate that the kinematics of the shark spiral intestine are more complicated than expected based on morphology, and the fluid flow in the intestine is likely highly regulated by intestinal muscular activity.

During tail regeneration in lizards the new corneous layer formed in the regenerating epidermis includes antimicrobial peptides, cystatin and serpins, likely forming an anti-microbial barrier. The present study aims to reveal other proteins potentially contributing to this protective barrier of the epidermis. Using immunohistochemistry we have detected a peptidoglycan-like recognition protein-3 (pglyrp3), an antimicrobial molecule, and an epidermal growth factor receptor kinase 8 l (eps8l), a receptor of EGF (Epidermal Growth Factor) that stimulates epidermal formation. The study shows that the two proteins are mostly accumulated in the forming wound epidermis and in the shedding layer of the regenerating scales. The shedding layer is the intra-epidermal layer that allows the separation of the initial corneous layer from the regenerating epidermis. While presence of pglyrp3 is likely related to the formation of the anti-microbial barrier, the function of the eps8l protein in epidermal regeneration remains unknown. Whether the latter protein is involved in keratinocyte movement within the regenerating epidermis has to be specifically determined in future studies. Together with the antimicrobial peptides cystatin and serpins, previously detected in the wound epidermis and shedding layer, the present study indicates that pglyp3, and potentially eps8l, contribute to protect the new skin and underlying regenerated tissues from the potential microbe invasion.

Functional morphology considers form and function to be intrinsically related. To understand organismal functions, a detailed knowledge of morphological and physiological traits is necessary. Regarding the respiratory system, the combined knowledge about pulmonary morphology and respiratory physiology is fundamental to understand how animals exchange gases and regulate critical functions to sustain metabolic activity. In the present study, the paucicameral lungs of Iguana iguana were analyzed morphometrically through stereological analysis using light and transmission electron images and compared with unicameral and multicameral lungs of six other non-avian reptiles. The morphological data were combined with physiological information to perform a principal component analysis (PCA) and phylogenetic tests of the relationship of the respiratory system. Iguana iguana, Lacerta viridis, and Salvator merianae presented similar pulmonary morphologies and physiologies when compared to Varanus examthematicus, Gekko gecko, Trachemys scripta, and Crocodylus niloticus. The former species showed an elevated respiratory surface area (%A_R), a high diffusion capacity, a low volume of total parenchyma (V_P), a low percentage of parenchyma concerning the lung volume (V_L), and a higher surface/volume ratio of the parenchyma (S_AR/V_P), with high respiratory frequency (f_R) and consequently total ventilation. The total parenchymal surface area (S_A), effective parenchymal surface-to-volume ratio (S_AR/V_P), respiratory surface area (S_AR), and anatomical diffusion factor (ADF) showed a phylogenetic signal, evidence that the morphological traits are more strongly correlated with the species' phylogeny than the physiological traits. In sum, our results indicated that the pulmonary morphology is intrinsically related to physiological traits of the respiratory system. Furthermore, phylogenetic signal tests also indicate that morphological traits are more likely to be evolutionary conserved than physiological traits, suggesting that evolutive physiological adaptations in the respiratory system could happen faster than morphological changes.