Acta Zoologica最新文献

Amphinomida, some also known as fireworms, are not only notorious for their painful sting but also their painfully difficult phylogenetic placement. Current understanding of the annelid tree of life suggests a close affinity with Sipuncula, the unsegmented and sessile peanut worms. This sister-group relationship is hard to explain from a morphological perspective. Here, we present the results of our histological and ultrastructural study of the central nervous system in two distantly related amphinomids: Euphrosine foliosa (Euphrosinidae) and Eurythoe complanta (Amphinomidae). We provide detailed morphological information, aiming to set up the groundwork for future comparative studies and to gain insight into the evolution of annelid nervous systems. We not only compare our observations among the two species but also discuss their implications for annelids in general and more specifically for the sipunculan affinity. The central nervous system in Amphinomida differs both from other errantian annelids and also from Sipuncula and shows no clear synapomorphies that would argue for or against their current phylogenetic placement.

Immunoreactivity for Dab2 and Foxp3 suggests that immune-suppressive cells are present in the regenerating tail blastema of lizard. Acta Zoologica (Stockolm). Tail regeneration in lizards likely occurs in immune-evasive conditions. In order to strengthen this hypothesis, the presence of the tumour suppressor and macrophage marker Dab2 and the lymphocyte regulatory marker, Foxp3, are evaluated by immunofluorescence in lizard regenerating blastema. The observations reveal sparse Dab2 and Foxp3 cells among blastema cells, identified, respectively, as healing M2-macrophages and Tregs-lymphocytes. Dab2 is also detected in basal/suprabasal layers of the apical wound epidermis, suggesting that this protein may participate in controlling cell proliferation of the growing tail by regulating Epidermal Mesenchymal Transition. Tregs marker, Foxp3, is localized in sparse cells among blastema mesenchymal cells and in the regenerating apical ependyma, suggesting the presence of immune cells that stimulate healing and sustain blastema growth. However, due to a similar 14 amino acid-long epitope between Foxp3 and Foxj1, the employed antibody might also recognize the latter protein, known to be involved in ciliogenesis of ependymal cells in fish and amphibians. It is, therefore, possible that Foxj1 may also be produced in the regenerating ependyma of lizards during ciliogenesis. The study further supports the hypothesis that lizard tail regeneration occurs in immune-tolerant conditions and that organ regeneration in vertebrates can only occur in an immune-suppressed or immune-evasive environment.

The anatomy of the African lion heart is not well documented, and assumptions are made that the anatomy is comparable to that of the domestic cat. The increasing demand for veterinary intervention in the African lion warrants sound anatomical knowledge of the heart. The heart is situated caudal to the thoracic limbs between ribs 4 and 6. It is covered by the left cranial lung lobe, and cranial and middle lobe of the right lung, respectively, with a prominent cardiac incisure present on the right. Two pericardial ligaments are present, the A. coronaria dextra is dominant, and the Atrium dextrum and Auricula dextra possess a vast network of Mm. pectinati. The massive thoracic limbs, adapted to bring down prey, appear to restrict the cranial thoracic cavity, and as a trade-off, the thoracic viscera are situated more caudally. During intense activity, the heart and lungs compete against each other for space, thus limiting physical activity to short, intense periods. Capacity for sudden increase of cardiac output is facilitated by the extensive Mm. pectinati of the Atrium dextrum. Intracardiac injection is recommended on the right, ventrally in intercostal space 5. The two pericardial ligaments may help to stabilize the heart during intense activity.

In this study, Chrysolina herbacea female reproductive system, differentiating stages of vitellogenesis, the egg chorion are examined with light and scanning electron microscopies. C. herbacea is chosen for this study because it is considered to be one of the most harmful insects that destroy mint plants, and it is an agricultural pest. Female reproductive system consists of a pair of ovaries, a pair of lateral oviducts, a common oviduct, spermathecae and a genital chamber. The ovary has 18 meroistic telotrophic ovariole. Each ovariole is divided into four regions: terminal filament, germarium, vitellarium and pedicel. Terminal filament is a long tubular structure. Germarium contains trophocytes (nurse cells), young oocytes and prefollicular cells. Vitellarium consists differentiating oogenic stages including developmental periods of previtellogenesis, vitellogenesis and choriogenesis. The ovarioles open into lateral oviduct by pedicel. The single spermatheca is located near the base of the common oviduct. Spermathecae consist of spermathecae reservoir for sperm storage and a short spermathecae duct. C. herbacea eggs are yellow and elongated. The structure of female reproductive system, the egg chorion and larva of C. herbacea are important to understand the outbreak of this insect pest and to biological control this harmful species.

In this study, we assessed the ovary structure and early oogenesis in representatives of Osteoglossomorpha, one of the most basal Teleostei groups. We aimed to perform a comparative analysis between internally fertilizing Pantodon buchholzi (Pantodontidae) and externally fertilizing Osteoglossum bicirrhosum (Osteoglossidae), Marcusenius cyprinoides, Brevimyrus niger, Gnathonemus petersii and Mormyrus rume (Mormyridae). Our results indicated differences in ovary structure between P. buchholzi and the externally fertilizing species, as well as a considerable disparity in oocyte organization in all studied species. All species possess ovaries of the cystovarian type. In P. buchholzi, the epithelium lining the lumen was columnar and formed crypts with ciliated and microvillus cells as well as deep invaginations with secretory cells, whereas in the remaining species epithelium was squamous. The organization of oogonia and one-nucleolus oocytes did not differ between species, there were variations in oocytes at subsequent steps of primary growth, including symmetry/asymmetry of the inner cell structure, differences in Balbiani body formation, presence/absence of zonation of the ooplasm, and differences in the order in which cortical alveoli and oil droplets appeared. These differences may be caused by a long and separate evolution of the families as well as adaptation to insemination in the family Pantodontidae.

Geographic distance and ecological conditions are important factors for phenological differentiation, and the adult morphological characters play significant role in several biological functions in insects. Present study showed significant intraspecific and intersex variation in colour pattern, number of spots and stripes on the forewings of Chilo partellus adults of different ecological populations. Females were comparatively light in colour with less black spots and stripes than the males across populations. Length and width of head, thorax and abdomen, wingspan, and various parts of male and female genitalia varied significantly across C. partellus populations. Abdomen, corpus bursae and papillae anales were significantly longer in females of Hisar as compared to other populations. However, the length of aedeagus was significantly longer in males of Coimbatore and Delhi as compared to other populations. Range of wingspan: body size and body size: genitalia ratios across C. partellus populations were wider in females than males. Wingspan: body size ratio was significantly lower in males of Raichur and females of Hisar and Parbhani as compared to other populations. Body size: genitalia ratio was significantly lower in males of Coimbatore and Hyderabad, and females of Coimbatore, Raichur and Surat as compared to other ecological populations. These findings suggest phenotypic plasticity in C. partellus having implications for phenotypic expression and greater fitness in response to changing climatic conditions.

The 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.

We discuss the use of the terms venom and poison, in the context of integrative biology, with particular emphasis on behaviour and natural history. Our purpose is to reach a broad scientific audience, especially that dedicated to zoology. The meaning of the two terms is reviewed from the secretory perspective, mainly focussed on the reptiles and amphibians. We justify the use of the two words, based on biological and behavioural differences.

The liver is a well-defined organ regarding its functions; however, it may present morphological variations among species. Since anurans may be exposed to toxic substances in their environment, which can disrupt liver's morphology and function, descriptive studies of organs are important to be carried out under natural condition. Thus, this study aimed to describe morphological aspects of liver in three Neotropical anuran species commonly used as experimental models: Physalaemus cuvieri (Leptodactylidae), Leptodactylus fuscus (Leptodactylidae) and Rhinella diptycha (Bufonidae). Anatomical, histological and ultrastructural analyses of six male samples of each species were carried out. A restricted analysis of the three species showed that livers' anatomy and ultrastructure are quite similar—they present three lobes, rounded nucleus polyhedral hepatocytes and some glycogen contents; however, histologically, there was a difference in the structural arrangements. In R. diptycha the parenchyma was arranged in a single cord, whereas in P. cuvieri and L. fuscus, there were double ones. This parenchyma structuring is highly variable considering Amphibia class. Knowledge about hepatic morphology and ultrastructure in amphibians is a key measure to detect changes in experimental studies and to infer about possible physiological and / or metabolic changes, when these animals are exposed to adverse conditions.

The body size and reproductive characteristics in populations of the same species is influenced by environmental and ecological factors. In this study, we analysed the relationship of environmental factors, morphological characters (body size and mass) and reproductive traits (clutch size) of females from 13 populations of Sceloporus variabilis. Results showed variation in snout‒vent length (SVL), body mass and clutch size among populations. An ANCOVA between SVL and clutch size showed an increase of the latter in females from Alvarado and Valle Nacional; ANCOVA between body mass and SVL revealed an increase in body mass in most populations. A canonical correlation analysis showed a positive relationship between SVL, body mass, and clutch size with elevation and precipitation, but not with temperature. Future studies should assess the effect of seasonality and food resource availability on reproductive investment among populations of S. variabilis to determine whether these characteristics are a function of differences in key ecological factors (e.g. availability of resources and seasonality) associated with each population, and determine the causes of geographic variation in morphological and life history characteristics among populations.