Translocation of aquaporin-containing vesicles to the plasma membrane is facilitated by actomyosin relaxation

Docking and fusion of vesicles to the plasma membrane is a fundamental process in living cells. An established model for the trafficking of vesicles is based on primary epithelial cells from the collecting duct of the nephron. Upon stimulation with the signaling peptide arginine-vasopressin (AVP), aquaporin-containing vesicles are directed to the plasma membrane. Since aquaporin selectively enhances the water permeability of plasma membranes, this process helps to balance the water content of the organism. A mechanism has been suggested involving local depolymerization of F-actin to facilitate the movement of vesicles to the membrane. Since F-actin is the major component of cytoskeletal restoring forces, AVP-stimulated cells can be expected to lose rigidity. Here, we used atomic force microscopy force mapping to test whether AVP alters cell stiffness. The Young's modulus of living epithelial cells at 37°C was continuously monitored, yielding a 51% decrease of Young's modulus after the addition of AVP. The data demonstrate that not the depolymerization of actin but a relaxation of actomyosin interaction facilitates vesicle translocation.     

Bergmann's and Rensch's rules and the spur‐thighed tortoise (Testudo graeca)

Body size is an ecologically important variable in animals. The geographical size variation of most snakes and some lizards counters Bergmann's rule in that, among related taxa, the larger ones live at warmer latitudes. However, exceptions notwithstanding, and despite being ectothermic, turtles as a group tend to obey Bergmann's rule. We examined this idea in Testudo graeca, ranging from Morocco to Romania and to Iran with disputed systematics, both at the global scale (using literature) and within the focal area of Israel (using museum specimens). Both globally and locally, carapace length correlated with latitude, in accordance with Bergmann's rule. The scant data on reproduction fully support the hypothesis that Bergmann's rule enables larger clutches where the climate would limit repeated clutches. The sexual size dimorphism (SSD) was approached using two methodologies: (1) ‘conventional’, using globally literature data and locally museum samples and (2) ‘innovated’, using photographs of copulating tortoises from Israel and Turkey. By each methodology, SSD emerged as being male biased in the larger‐bodied populations and female biased in the smaller‐bodied populations, obeying Rensch's rule. Some observations support the hypothesis that the evolution of large males serves intermale combating. Finally, Rensch's rule was found to apply separately within Anatolia and within the Levant, possibly indicating that these populations are separate.     

Description of two new species of the genus Gobio (Teleostei: Cyprinidae) from the Black Sea coast of Turkey

Thesystematics of the genus Gobio, especially of the populations on the southern Black Sea coast, seems to be still far from being resolved. Seven species were rec-orded from the northern Black Sea coast while three species were recognized from the southern Black Sea coast. We examined in total 43 specimens from K?z?l?rmak River (southern Black Sea basin), 80 specimens from Çoruh River (the Western Cau-casus of the Black Sea basin), 14 specimens from Rioni River (the Western Caucasus of the Black Sea basin), and 6 specimens from Kherota and Shakhe Rivers (the Western Caucasus of the Black Sea basin). Based on an analysis of 32 metric and 5 meristic data as well as the number of vertebrae, we concluded that the K?z?l?rmak and Coruh populations are two distinct, unnamed species, and we describe them here as Gobio kizilirmakensis from the K?z?l?rmak River and G. artvinicus from the Çoruh River.

http://www.zoobank.org/urn:urn:lsid:zoobank.org:pub:1ED54FB1-588F-4412-B376-4BE4E4516EB1     

Squalius semae,a new species of chub from the Euphrates River,Eastern Anatolia (Teleostei: Cyprinidae)

In a study of the fishes of the Euphrates River (Persian Gulf basin) three species of Squalius belonging to the cephalus-group were found: The Tohma population was identified as S. seyhanensis and the Merzimen and Hilvan populations as S. berak. The comparison of 28 metric and 5 meristic parameters and morphological characters showed that the populations of the northern Euphrates River drainages are distinct and belong to a hitherto unnamed species. We describe it here as Squalius semae sp. n.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:D195B69C-C6CB-4DEB-B85D-5B695F917CE5     

Phylogenetic relationships of nine mullet species (Mugilidae) in the Mediterranean Sea

Phylogenetic relationships among four genera and nine species (Mugil cephalus, Mugil soiuy, Liza ramada, Liza aurata, Liza abu, Liza saliens, Liza carinata, Chelon labrosus, Oedalechilus labeo) of the Mediterranean mullets (Mugilidae) were investigated by means of allozyme electrophoresis using a seven-enzyme system (CK*, GAPDH*, G3PDH*, IDHP*, ME*, MDH*, PGM*) comprising eleven putative loci. The highest genetic divergence was 1.299, detected between M. cephalus and L. aurata and the lowest (0.280) was found between L. carinata and L. saliens. The amount of genetic divergence between the genera Chelon and Oedalechilus did not appear to be high (0.285). In a UPGMA tree, all nine species were grouped in two main branchings. In the first branch, C. labrosus and O. labeo clustered as closest taxa and were sister group to L. ramada. The other four Liza species produced two sub-branching in this group; L. carinata branched together with L. saliens, and L. aurata branched together with L. abu. In the second branch the two species of the genus Mugil, M. cephalus and M. soiuy, clustered together and were clearly isolated from the other three genera.     

Genetic differentiation of Mediterranean horse mackerel (Trachurus mediterraneus) populations as revealed by mtDNA PCR-RFLP analysis

The genetic population structure of Mediterranean horse mackerel, Trachurus mediterraneus , from seven locations throughout the Black, Marmara, Aegean and eastern Mediterranean seas was investigated using restriction fragment length polymorphism (RFLP) analysis of the mtDNA 16S rDNA region. An approximately 2000-bp segment was screened in 280 individuals using six restriction enzymes, resulting in 10 composite haplotypes. The most common haplotype was present in 56.42% individuals; the next most frequent haplotype was present in 22.85% individuals. Average haplotype diversity within samples was moderate (0.38), and nucleotide diversity was low (0.00435). Mean nucleotide divergence for the seven sampling sites was 0.0028. Nucleotide divergence among samples was moderate, with the highest value detected between the Aegean Sea (Izmir) and the eastern Black Sea (Trabzon) populations (0.007055), and the lowest (−0.000043) between the Marmara Sea (Adalar) and the western Black Sea (Sile) populations. In Monte Carlo pairwise comparisons of haplotype frequencies, the Sinop from the middle Black Sea, Trabzon from the eastern Black Sea, and Iskenderun Bay from the north-eastern Mediterranean Sea exhibited highly significant (P   <   0.001) geographical differentiation from each other and from all other populations. Mantel's test indicated that the nucleotide divergence among populations of T. mediterraneus was not significantly associated with their geographical isolation ( r  = −0.2963; P   >   0.05). Consequently, the mtDNA 16S rDNA region provided evidence for the existence of three distinct T. mediterraneus populations (Sinop, Trabzon and Iskenderun Bay) in the Black and north-eastern Mediterranean seas.