Non-indigenous species along the Israeli Mediterranean coast: tally,policy, outlook

Hydrobiologia - Of the 452 multicellular non-indigenous species (NIS) recorded off the Israeli Mediterranean coast, nearly 90% are considered to have been introduced through the Suez Canal...     

Intra-individual heterogeneity of rDNA allows the distinction between two closely related species in the Genus Helianthus

The Ribosomal DNAs of Helianthus annuus and H. argophyllus were analysed. Total DNA from single individuals of six cultivated lines, one wild ecotype ofH. annuus, and three ecotypes of H. argophyllus, were digested with various restriction enzymes. Hybridisation of Southern blots with sunflower ribosomal probes containing most of the interspacer regions (R3) or the 25 s coding region (R2) reveals different patterns from those expected: while no difference between H. annuus and H. argophyllus had been observed in previous rDNA RFLP analysis, our study clearly distinguished the two species on the basis of two different patterns when using R3 and BamHI, BstYI, or EcoRI/BamHI. Furthermore, the sum of the fragment weights of the BamHI restriction patterns was much greater than that of the rDNA entire unit-weight space. The co-existence of different rDNA units within single individuals is proposed as a model to explain these results. Four rDNA units were distinguished, which differed in their state of methylation and by the presence of mutations at two BamRI restriction sites. H. annuus individuals displayed two types of rDNA units while H. argophyllus individuals displayed four types.     

Lateral differences in GABA binding sites in rat brain

An asymmetric distribution of GABA binding sites was found in the cerebral cortex, hippocampus, cerebellar hemispheres, striatum, and thalamus. Higher levels of [³H]GABA binding were observed in the left-side of most brain areas and in a greater percentage of adult rats, but the opposite asymmetry was found in the thalamus. A similar left-right difference in cerebral hemispheres was also found in five day-old rats, suggesting the genetic predetermination of asymmetry.     

Chain conformation in polyretropeptides: Quantum mechanical and empirical force field calculations on 2,6,8-trioxo-3,5,9-triazadecane,a model compound for poly(retro-glycine)

We report here our results on semiempirical AM1 calculations for the conformational preferences of 2,6,8-trioxo-3,5,9-triazadecane, a model compound for polymers made of retropeptide units. We have evaluated the effect of applying symmetry constraints between chemically equivalent torsion angles. These results suggest that preferred conformations around the ? NH? CH₂? NH? group are quite independent from those on the ? CO? CH₂? CO? unit, so all possible combinations generate the complete set of energy minima for the model compound. We have analyzed the implications of the different minimum energy conformation in an infinite chain model and we have explored the conformational space of regular polyretropeptides. This shows a close relation to that of regular polypeptides but with significant differences arising from the change of orientation of the peptide units along the polymer molecule. The energy calculations also support previously proposed models for the crystal structure of the simplest polyretropeptide, poly(retro-glycine). Finally, we discuss the consequences of retropeptide-peptide copolymerization as well as the expected conformations for regular alternate terpolymers. © 1995 John Wiley & Sons, Inc.     

Invasive Carassius carp in Georgia： Current state of knowledge and future perspectives

In Georgia, crucian carp Carassius carassius （Linnaeus, 1758） was known from only one locality after Kessler＇s record （1877-1878） with no new findings until 1985. Since then C. carassius rapidly and simultaneously invaded almost all water bodies of Georgia. In 2004, it was for the first time noted that this invasive Carassius sp. could not be a C. Carassius, but was a form of Carassius gibelio （Bloch, 1792）. However no further data is available about this invasive species in Georgia. The aim of the present study was to investigate taxonomic status of Carassius sp. in Georgia using mtDNA phylogenetic analyses and mor- phometrie study of truss network system. Genetic analysis revealed that invasive Carassius sp. is closely related to the C. gibelio from Turkey and other countries. In contrast, morphometrically Carassius sp. from Georgia can be easily differentiated from those of Turkey indicating high intraspecific variability. This is the first time discussion on the current knowledge of the present distribution of invasive carp in Georgia with identifying current problems and future research directions needed.     

Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei,Aulopiformes, Synodontidae)

Fishelson, L., Golani, D., Russell, B., Galil, B. and Goren, M. 2012. Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae). —Acta Zoologica (Stockholm) 93 : 308–318. This study compares the morphology and cytology of the alimentary tract in several species of lizardfishes (Synodontidae, Teleostei) of the genera Saurida, Synodus, and Trachinocephalus, in relation to their diets and bathymetric distribution. All the studied species feature a large, pouch‐like stomach, with the intestine beginning at the stomach’s anterior apex, adjacent to the esophageal opening. In the more ‘microphagous’Synodus spp. and Trachinocephalus, the intestine bends twice before reaching the anus, whereas in the more ‘macrophagous’Saurida spp., the intestine extends straight to the anus. The species differ also in the number and form of their pyloric ceca, the length of the intestine and in the percentile relationship between stomach length and standard body length. Along the alimentary tract folds and villi protrude into the lumen, their numbers differing on various sites of the tract. Three cell types make up the gastric gland system: (1) pyramidal cells forming the tubular gastric glands in the lamina propria; among them are large, pale secretary cells; (2) groups of neck cells that surround the pits of the tubules; and (3) groups of large and granule‐rich cells at the end portion of the stomach. All species are carnivorous and uniform in morphology, the differences in the alimentary tract found between the more shallow‐water species of Synodus and Trachinocephalus, and the deeper‐dwelling Saurida, seem to be only partly correlated with the differences in diet.