Acta Zoologica

doi: 10.1111/azo.12473pmid: N/A

Alibardi, Lorenzo

doi: 10.1111/azo.12487pmid: N/A

The present review formulates an evolutionary hypothesis on the distribution of regeneration in invertebrates and vertebrates. Regeneration is a basal ancestral property of animals living in aqueous environment where life was generated. The specific life cycles that evolved in each phylum indicate that only adult aquatic animals with asexual reproduction, larval stages and metamorphosis, possess broad regenerative abilities, protostomes or deuterostomes. Regeneration derives from the re‐utilization in different forms of numerous developmental gene pathways active during development and the transitional phases of larval metamorphosis. An injured adult animal, composed of differentiated tissues, cannot repeat the same sequence of gene activation of embryogenesis, resulting in a variable regeneration (most aquatic invertebrates and anamiotes). In contrast, species with a genome that is not programmed for producing larvae and intense metamorphosis, mainly terrestrial (numerous nematodes, arthropods and amniotes), cannot regenerate their organs after injury. It is hypothesized that during the evolution of terrestrial animals, they lost genes involved in regeneration so that they repair by wound healing associated with grow (regengrow) or by scarring. Future molecular knowledge on developmental pathways that evolved in regenerating competent animals will tell us whether or not organ regeneration in regenerative incompetent animals will be feasible.

Stemme, Torben

doi: 10.1111/azo.12466pmid: N/A

Although scorpions have comparatively low regenerative potential, legs and pedipalps are able to regenerate some structures in an often incomplete manner. The most intriguing scorpion appendages are the ventrally located pectines. These organs are equipped with numerous sensilla that scan the substrate for mechanosensory‐ and chemosensory cues. Due to their ventral position and frequent substrate contact, pectines are vulnerable to traumatic injuries. Pecten malformations have been hypothesized to be the result of incomplete regeneration. To investigate their regeneration capabilities, the pectines of postembryonic stages of Euscorpius italicus (Herbst, 1800) were amputated before the second moult at three different positions. Data on intermoult periods and the number of pectinal teeth were gathered for approximately 2.5 years. The regeneration process on exuviae of up to six moulting events was documented by photographs and confocal laser‐scanning microscopy. Regardless of the amputation site, no evidence for regenerative capabilities of pectines in E. italicus could be reported. Thus, incomplete regenerations mentioned in the literature are likely the result of simple wound healing. Depending on habitat complexity, substrate contact time of the pectines seem to differ, which might be interpreted as a trade‐off between highest sensory input and the avoidance of traumatic injury of the pectines.

Suzuki, Hirohumi; Isobe, Ami; Yamamoto, Toshiharu

doi: 10.1111/azo.12468pmid: N/A

This is the first study to examine the distribution of a chemokine CXCL14‐like peptide in the pituitary and hypothalamus of an avian species, the Japanese quail (Coturnix japonica). We employed immunohistochemical techniques using a specific anti‐human CXCL14 antibody. CXCL14‐immunoreactive cells were detected in the caudal lobe of the pars distalis. CXCL14‐immunoreactive puncta were densely distributed in the external layer and sparsely distributed in the internal layer of the median eminence. CXCL14 staining was absent after pre‐absorption of the antibody with recombinant human CXCL14. All CXCL14‐immunoreactive cells corresponded to growth hormone (GH)‐producing cells in the caudal lobe. In addition, the majority of CXCL14‐immunoreactive puncta in the median eminence corresponded to somatostatin‐containing fibres. CXCL14 secreted from GH‐producing cells and somatostatin‐containing fibres may act as an inhibitor of GH release via an autocrine mechanism and neuroendocrine signalling, respectively.

Esmaeili, Hamid Reza; Echreshavi, Sorour; Masoumi, Amir Hassan; Nejad, Abbas Motlagh

doi: 10.1111/azo.12469pmid: N/A

Secondary sexual dimorphism is an interesting and stupendous subject of research study due to the fact that it is a result of sexual selection, mostly attributed to either female mate choice or male–male competition. This study aims to investigate the microscopic characterization of scales and fin rays in several aphaniids (Cyprinodontiformes: Aphaniidae) to find out the possibility of using these structures as secondary sexual dimorphism traits and discuss their taxonomic and evolutionary significance. Herein, the results reveal that (i) male individuals of aphaniid species of the genera Aphanius, Aphaniops and Paraphanius present contact organs in the forms of ctenus‐like structure (in posterior margin of the scales) and spicule‐like structure (in anal fin rays) that show sexual dimorphism of scales and fins; (ii) number, position, size and shape of contact organs provide taxonomic signal to distinguish members of the genus Aphaniops from two other genera; (iii) females of Aphaniops ginaonis also represent contact organs in scales but fewer than males and (iv) as the sexual dimorphism results from different sexual selection pressures acting on males and females, it provides evolutionary signals.

Cheij, Esteban; Olea, Gabriela Beatriz; Rodríguez, Florencia; Céspedez, Jorge; Flores Quintana, Carolina

doi: 10.1111/azo.12470pmid: N/A

This study aims to characterize the gonads, folliculogenesis, and spermatogenesis processes of male and female Rhinella bergi through anatomical, histological and morphometric analysis. We worked with specimens previously collected in the spring and summer seasons (2014–2015), in which the gonads were studied based on morphological, histological and morphometric analysis. The reproductive system was analyzed using a stereoscopic microscope and a scanning electron microscope (SEM). Histological preparations were made following the conventional protocol of dehydration, inclusion in paraffin and stained with haematoxylin–eosin, Mallory trichrome and PAS histochemical reactions. The anatomical and morphometric characteristics and the gametogenesis in R. bergi agree with what was proposed for other analyzed species of the Bufonidae family. Females with ovaries with oocytes in different stages of maturity and postovulatory females were found. The males presented continuous spermatogenesis. The results of this work serve as a basis for the characterization of the reproductive cycle in R. bergi and, at the same time, provide background information on the analysis of gametogenic activity. Future investigations will be focused on evaluating the reproductive cycle in this species, both in ovaries and testes as well as Bidder's organ, to compare and correlate with the results obtained in this study.

Alesci, Alessio; Messina, Emmanuele; Zuwala, Krystyna; Fumia, Angelo; Miller, Anthea; D'Angelo, Roberta; Kuciel, Michal; Albano, Marco; Savoca, Serena; Capillo, Gioele

doi: 10.1111/azo.12475pmid: N/A

Ciliated and non‐ciliated mechanosensory cells in invertebrates have intricate cytoskeletal structures that, combined with microtubules, act as a mechanical link between external stimulus and signal processing. As a result, they can perceive forces like touch, cuticle deformation, gravity and sound. Through the expression of antibodies against serotonin (5‐HT), calbindin, inducible nitric oxide synthase (iNOS) and α‐smooth muscle actin (αSMA), this research aims to investigate mechanosensory cells in the integument of Lumbricus terrestris (Linnaeus, 1758) in an evolutionary perspective. In the epidermis, we discovered isolated mechanosensory cells that were immunopositive to every antibody examined. Our findings improve the knowledge and the evolution of annelid sensory biology adding new insights on the sensory signal transduction and help to better understand the morpho‐structural adaptations of invertebrate skin on an evolutionary scale and to give more taxonomic data for species distinction.

Masoumi, Amir Hassan; Esmaeili, Hamid Reza; Sadeghi, Reza

doi: 10.1111/azo.12476pmid: N/A

Otolith morphology in the toothcarps of the family Aphaniidae is an important source of taxonomic information. However, little is known about the ontogenetic variation in otolith morphology. In this study, the development of otolith morphology in different life stages of Aphaniops kruppi, an endemic toothcarp of the Arabian Peninsula, is described and discussed. The results reveal (i) a significant correlation between standard length and otolith size (length) in larval and early juvenile stages, (ii) clear differences in otolith morphology between larvae/early juveniles and adults, and (iii) a temporal link between the appearance of the sulcus on the otolith's inner face and lifestyles, that is demersal in larvae and early juveniles, and pelagic in adults. Moreover, our new data on otoliths of Ap. kruppi propose that otoliths of larvae or early juveniles of Ap. kruppi can be recognized by adults not only because of their small size but also based on their short and rounded rostrum and antirostrum and shallow, wide excisura. As the above‐mentioned characteristics are also found in the otoliths of juveniles and larvae of several other studied aphaniids, it can be concluded that otoliths are not diagnostic at the species level in Ap. kruppi, and this holds for other closely related species.

Degan, Massimo; Alibardi, Lorenzo

doi: 10.1111/azo.12477pmid: N/A

Tail regeneration in lizards derives from the formation of a regenerative blastema. Numerous snoRNAs exclusively up‐regulated in the regenerating tail but absent in the scarring limb of the lizard Podarcis muralis have been detected suggesting they are key genes for regeneration. While most snord‐, snora‐ and scarna‐RNAs are activators of protein synthesis and cell proliferation (oncogenes) some may also be tumour suppressors. A tail blastema of 2–3 mm in length consists of proliferating mesenchymal cells, fibroblasts and keratinocytes with active nucleoli, rosette‐patterned ribosomes and few rough endoplasmic cisternae. In few days, the blastema grows into a new tail indicating intense protein synthesis within this short period. A quantitative RT‐PCR analysis of snord87, snord26, snord74, snora63, scarna11, U2 and U4 shows that, aside snord87, the other ncRNAs are up‐regulated, particularly, U2, U4 and scarna11. These ncRNAs might regulate the rate of production of ribosomes from the nucleolus (snora‐ and snord‐RNAs), the splicing process (snord‐ and scarna‐RNAs, U2 and U4), the speed of protein synthesis (snora‐ and snord‐RNAs) and cell proliferation in the blastema. These non‐coding‐RNAs are hypothesized to intensify the production of more functional ribosomes that accelerate the rate of protein synthesis and rapid growth of the blastema into a new tail.

García‐Rosales, Aaron; Cruz‐Elizalde, Raciel; Ramírez‐Bautista, Aurelio; Hernández‐Camacho, Norma

doi: 10.1111/azo.12478pmid: N/A

Caudal autotomy is a behaviour in lizards that favours survival but brings with it some associated costs, mainly loss of energy, which is related to the position of the breaking point. Moreover, the frequency of tail loss can vary at different levels, between sexes, populations, seasons and at an intra‐ and inter‐population level. In this study, we analysed the breaking position of the tails in individuals and frequencies of tail loss between years, sexes, seasons and populations of the lizard Sceloporus variabilis that inhabit contrasting environments. The results showed a low frequency of tail loss at the ends (distal and proximal) of this organ (except for individuals from the xeric scrubland population) and there was a higher proportion of complete than incomplete tails in lizards for all analysed populations. Also, there was no variation in the frequency of tail loss among populations, sexes (except in one population), years or seasons. A higher proportion of organisms with complete tails suggests that this organ is an important element for these lizards. In addition, the lack of variation in the frequency of tail loss may indicate a similar behaviour such as escape from predators among the groups analysed.