Magnetosensation in zebrafish

Many species, from bacteria to vertebrates, have been reported to use the geomagnetic field as a major cue for oriented short and long range migration 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., but the molecular nature of the underlying receptor has remained elusive. One of the main reasons may be that past attempts to train animals to respond to magnetic stimuli proved surprisingly difficult [11]. We present a novel approach to magnetic conditioning, using a fast, fully automated assay system relying on negative reinforcement. Weak electric impulses were applied to punish fish that failed to escape upon magnetic field alterations (avoidance behaviour). Using this assay we first demonstrate magnetosensation in Mozambique tilapia, a fish migrating regularly between freshwater and the sea. Next we wondered whether non-migratory fish have a magnetic sense, such as zebrafish, the genetic fish model organism. Zebrafish were trained in groups of 4 individuals, and statistically highly significant reactions to magnetic field changes were recorded. The demonstration of magnetosensation in zebrafish opens a possibility to genetically identify the magnetoreceptor and its downstream signalling cascade.     

Marker-Dependent Recombination in T4 Bacteriophage. IV. Recombinational Effects of Antimutator T4 DNA Polymerase

Recombinational effects of the antimutator allele tsL42 of gene 43 of phage T4, encoding DNA polymerase, were studied in crosses between rIIB mutants. Recombination under tsL42-restricted conditions differed from the normal one in several respects: (1) basic recombination was enhanced, especially within very short distances; (2) mismatch repair tracts were shortened, while the contribution of mismatch repair to recombination was not changed; (3) marker interference at very short distances was augmented. We infer that the T4 DNA polymerase is directly involved in mismatch repair, performing both excision of a nonmatched single strand (by its 3' -> 5' exonuclease) and filling the resulting gap. A pathway for the mismatch repair was substantiated; it includes sequential action of endo VII (gp49) -> 3'->5' exonuclease (gp43) -> DNA polymerase (gp43) -> DNA ligase (gp30). It is argued that the marker interference at very short distances may result from the same sequence of events during the final processing of recombinational intermediates.     

Update on the praying mantises (Insecta: Mantodea) of South-East Vietnam

A report of Mantodea species collected in South-East Vietnam (provinces Dong Nai, Binh Phuoc and Lam Dong) is presented. New for Vietnam are the subfamily Phyllothelyinae, the tribe Anaxarchini of the subfamily Hymenopodinae and the species Leptomantella lactea (Saussure, 1870), Tropidomantis gressitti Tinkham, 1937, Amantis bolivari Giglio-Tos, 1915, Anaxarcha graminea Stål, 1877, Creobroter nebulosa Zheng, 1988, Phyllothelys breve (Wang, 1993), Ceratocrania macra Westwood, 1889, Ceratomantis saussuri Wood-Mason, 1876 and Theopompa tosta Stål, 1877, as well as five additional species whose precise identifications are less certain. Eighteen species are new for the South-East region and seven are new for the provinces sampled. The fauna of Vietnam now contains 69 species of Mantodea, 40 of which occur in the South-East region. Morphological, taxonomical and identification details for selected species are discussed and illustrated.     

Population parameters and exploitation rate of Sarotherodon galilaeus galilaeus (Cichlidae) in Lakes Doukon and Togbadji,Benin

Growth, mortality, recruitment and relative yield per recruit of Sarotherodon galilaeus galilaeus from Lakes Doukon and Togbadji were studied. Data on total length, total weight and sex were recorded on a monthly basis between January and December 2013 for S. g. galilaeus captured by local fishers. The estimated asymptotic lengths L_∞ were 26.2 and 23.6?cm for Lakes Doukon and Togbadji, respectively, while the growth rate K was 0.73 in Lake Doukon and 0.87 in Lake Togbadji. Estimates of fishing mortality, 0.27 and 0.47 y^?1 for Doukon and Togbadji, respectively, were low relative to natural mortality, 1.51 and 1.74 y^?1, respectively. Sizes at first sexual maturity were 12.8 and 13.2?cm for females and males, respectively, in Lake Doukon, and 11.5 and 12.4?cm for females and males, respectively, in Lake Togbadji. The size at first capture was estimated at 13.3 and 12.7?cm for Lakes Doukon and Togbadji, respectively, which, in the light of the size at maturity estimates, indicates that fish spawn at least once before capture. The current exploitation rates of 0.15 for Lake Doukon and 0.21 for Lake Togbadji suggest that their stocks of S. g. galilaeus are not overexploited in either lake.     

Histopathological biomarkers and genotoxicity in gill and liver tissues of Nile tilapia Oreochromis niloticus from a polluted part of the Nile River,Egypt

Fish health is affected by water pollution. Oreochromis niloticus collected during summer 2014 from El-Serw, a polluted site on the Nile River, were compared with fish from a reference site, El-Zamalek. Histopathological changes were detected in gill and liver tissue samples using light and electron microscopy. In addition, the degree of DNA damage was measured using the comet assay. To indicate the severity of water pollution at the two sites, physico-chemical properties and heavy metal concentrations were investigated. Gill damage, including lamellar cell hyperplasia and aneurysm, was observed in the fish samples from the polluted site. The livers of fish from the polluted area showed necrosis and an increase in melanomacrophage centres. Histochemical results confirmed a marked rise of gill mucopolysaccharides and a reduction of carbohydrate stored in hepatocytes. Electron microscopy revealed clear alterations in gill and liver tissue of fish from the polluted site. The comet assay showed highly significant DNA damage in tilapia collected from the polluted site, compared to those from the reference site. Histopathological biomarkers and the comet assay may therefore be sensitive indicators of exposure to mixtures of aquatic pollutants in Nile tilapia.     

Immune Checkpoints of the B7 Family. Part 2. Representatives of the B7 Family B7-H3, B7-H4, B7-H5, B7-H6, B7-H7, and ILDR2 and Their Receptors

Russian Journal of Bioorganic Chemistry - Immune checkpoints regulate polarity, strength, and termination of the immune response. The leading roles in these processes are played by molecules of the...