Genetic structure and relationships among anadromous and landlocked populations of rainbow smelt, Osmerus mordax, Mitchill, as revealed by mtDNA restriction analysis

Larvae of anadromous rainbow smelt originating in various spawning tributaries are retained in the St Lawrence estuary. We proposed that these smelt represent one population genetically differentiated from adjacent populations characterized by geographically distinct larval retention areas. We also analysed four landlocked populations to evaluate the phylogenetic basis of dwarf and normal-sized phenotypes and their relation to an adromous smelt. A phylogenetic distinction was revealed between anadromous and landlocked smelt, with only one of the two mtDNA phylogenetic groups of anadromous fish observed among landlocked smelt. Significant geographical heterogeneity in the distribution of mtDNA genotypes was observed among landlocked smelt, suggesting that dwarfism in smelt may be polyphyletic in origin. St Lawrence smelt were genetically identical but distinct from adjacent populations, supporting the proposition that population genetic structure reflects the number of larval retention zones rather than spawning sites.     

Presence of ornithine decarboxylase antizyme in primary cultured hepatocytes of the frog Xenopus laevis

Ornithine decarboxylase (ODC; EC 4.1.1.17) could be induced in primary cultured hepatocytes of the frog, Xenopus laevis, by a hypotonic treatment. Addition of 10 mM putrescine caused a rapid decay of preinduced ODC after a lag period of 30 min. The putrescine-induced ODC decay was faster than the ODC decay in the presence of cycloheximide. Simultaneous addition of cycloheximide blocked the putrescine-induced acceleration of ODC decay, indicating an involvement of protein synthesis. Addition of putrescine to normal medium caused complete loss of ODC activity in 2 h and then ODC-inhibitory activity appeared and progressively increased. The inhibitory factor was non-dialysable and temperature-sensitive and showed a time-independent and stoichiometric pattern of ODC inhibition. On the basis of these observations the inhibitory factor was identified as ODC antizyme. These results indicated that in frog hepatocytes, like in mammalian cells and tissues, ODC is under negative feedback regulation mediated by antizyme.     

Increase in the rate of recombinants in tomato (Lycopersicon esculentum L.) after in vitro regeneration

Summary Modification to the cross-over (C. O.) rate of tomato (Lycopersicon esculentum) was attempted by using in vitro plant regeneration. F1 hybrids with the same genetical homozygous background were compared at two loci: bs-ms32 on chromosome I, and aa-d on chromosome II. For each, the genetic distance separating the two markers was about 20 to 30 map units. One cotyledon of each F2 hybrid seedling was used as in vitro tissue culture material, while the rest of the plantlet was grown as a control. Recombination rates of the selfed progenies from each regenerated and matched control couple were compared. For the first set of markers 59,000 seeds were analysed (5 controls' and 7 regenerated progenies), and for the second, 11,000 (5 controls' and 8 regenerated progenies). There were significant increases in the genetic distance between markers in about half the regenerated individuals. For the first set the increases ranged from 6.07 to 6.91 units out of a control distance of the 19.84 to 25.65, corresponding to lengthenings of 30.59 to 35.29%. For the second set they ranged from 4.92 to 6.04 out of a control distance of 25.05 to 26.57, representing increases of 19.64 to 22.75%. Such a phenomenon can be important either from a fundamental or practical viewpoint, regarding selection efficiency in plants, and potential for gene reassortment.The experiment reported in this paper has been submitted by M. Biglary in partial fulfillment of the requirements for Docteur-Ingénieur degree. (Nov. 1982, Laboratoire d'Amélioration des Plantes, Université Paris-Sud, F-91405 Orsay)     

Neuroprotective Potential of Bacopa monnieri and Bacoside A Against Dopamine Receptor Dysfunction in the Cerebral Cortex of Neonatal Hypoglycaemic Rats

Neonatal hypoglycaemia initiates a series of events leading to neuronal death, even if glucose and glycogen stores return to normal. Disturbances in the cortical dopaminergic function affect memory and cognition. We recommend Bacopa monnieri extract or Bacoside A to treat neonatal hypoglycaemia. We investigated the alterations in dopaminergic functions by studying the Dopamine D1 and D2 receptor subtypes. Receptor-binding studies revealed a significant decrease (p < 0.001) in dopamine D1 receptor number in the hypoglycaemic condition, suggesting cognitive dysfunction. cAMP content was significantly (p < 0.001) downregulated in hypoglycaemic neonatal rats indicating the reduction in cell signalling of the dopamine D1 receptors. It is attributed to the deficits in spatial learning and memory. Hypoglycaemic neonatal rats treated with Bacopa extract alone and Bacoside A ameliorated the dopaminergic and cAMP imbalance as effectively as the glucose therapy. The upregulated Bax expression in the present study indicates the high cell death in hypoglycaemic neonatal rats. Enzyme assay of SOD confirmed cortical cell death due to free radical accumulation. The gene expression of SOD in the cortex was significantly downregulated (p < 0.001). Bacopa treatment showed a significant reversal in the altered gene expression parameters (p < 0.001) of Bax and SOD. Our results suggest that in the rat experimental model of neonatal hypoglycaemia, Bacopa extract improved alterations in D1, D2 receptor expression, cAMP signalling and cell death resulting from oxidative stress. This is an important area of study given the significant motor and cognitive impairment that may arise from neonatal hypoglycaemia if proper treatment is not implemented.     

Heregulin-induced epigenetic regulation of the utrophin-A promoter

Utrophin is the autosomal homolog of dystrophin, the product of the Duchenne's muscular dystrophy (DMD) locus. Utrophin is of therapeutic interest since its over-expression can compensate dystrophin's absence. Utrophin is enriched at neuromuscular junctions due to heregulin-mediated utrophin-A promoter activation. We demonstrate that heregulin activated MSK1/2 and phosphorylated histone H3 at serine 10 in cultured C2C12 muscle cells, in an ERK-dependent manner. MSK1/2 inhibition suppressed heregulin-mediated utrophin-A activation. MSK1 over-expression potentiated heregulin-mediated utrophin-A activation and chromatin remodeling at the utrophin-A promoter. These results identify MSK1/2 as key effectors modulating utrophin-A expression as well as identify novel targets for DMD therapy.     

High fidelity epigenetic inheritance: Information theoretic model predicts threshold filling of histone modifications post replication

During cell devision, maintaining the epigenetic information encoded in histone modification patterns is crucial for survival and identity of cells. The faithful inheritance of the histone marks from the parental to the daughter strands is a puzzle, given that each strand gets only half of the parental nucleosomes. Mapping DNA replication and reconstruction of modifications to equivalent problems in communication of information, we ask how well enzymes can recover the parental modifications, if they were ideal computing machines. Studying a parameter regime where realistic enzymes can function, our analysis predicts that enzymes may implement a critical threshold filling algorithm which fills unmodified regions of length at most k. This algorithm, motivated from communication theory, is derived from the maximum à posteriori probability (MAP) decoding which identifies the most probable modification sequence based on available observations. Simulations using our method produce modification patterns similar to what has been observed in recent experiments. We also show that our results can be naturally extended to explain inheritance of spatially distinct antagonistic modifications.     

Concentration dependent growth/non-growth linked kinetics of endosulfan biodegradation by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis>

The rates of biodegradation of endosulfan by P. aeruginosa were determined with different initial endosulfan concentrations (10, 50, 100, 150, 200 and 250 mg l⁻¹) and different growth linked kinetic models were fitted at these concentrations. At 10 mg endosulfan l⁻¹, Monod no growth model was well fitted. Monod with growth model described the biodegradation pattern at an initial concentration of 50, 100 and 150 mg endosulfan l⁻¹. Significant increases of P. aeruginosa MN2B14 density in broth culture during incubation further support this result. Conversely, zero order kinetic model was well fitted into the biodegradation data if initial endosulfan concentration was ≥200 mg endosulfan l⁻¹. The kinetics of endosulfan biodegradation by P. aeruginosa MN2B14 in liquid broth was highly dependent upon its initial concentration. The results of this study could be employed for predicting the persistence of endosulfan in water environment containing P. aeruginosa as an endosulfan degrading bacterium.     

Natural Rabies Infection in a Domestic Fowl (Gallus domesticus): A Report from India

Background

Rabies is a fatal encephalitis caused by viruses belonging to the genus Lyssavirus of the family Rhabdoviridae. It is a viral disease primarily affecting mammals, though all warm blooded animals are susceptible. Experimental rabies virus infection in birds has been reported, but naturally occurring infection of birds has been documented very rarely.

Principal Findings

The carcass of a domestic fowl (Gallus domesticus), which had been bitten by a stray dog one month back, was brought to the rabies diagnostic laboratory. A necropsy was performed and the brain tissue obtained was subjected to laboratory tests for rabies. The brain tissue was positive for rabies viral antigens by fluorescent antibody test (FAT) confirming a diagnosis of rabies. Phylogenetic analysis based on nucleoprotein gene sequencing revealed that the rabies virus strain from the domestic fowl belonged to a distinct and relatively rare Indian subcontinent lineage.

Significance

This case of naturally acquired rabies infection in a bird species, Gallus domesticus, being reported for the first time in India, was identified from an area which has a significant stray dog population and is highly endemic for canine rabies. It indicates that spill over of infection even to an unusual host is possible in highly endemic areas. Lack of any clinical signs, and fewer opportunities for diagnostic laboratory testing of suspected rabies in birds, may be the reason for disease in these species being undiagnosed and probably under-reported. Butchering and handling of rabies virus- infected poultry may pose a potential exposure risk.     

Differential response of etiolated pea seedlings to inoculation with rhizobacteria capable of utilizing 1-aminocyclopropane-1-carboxylate or L-methionine

The majority of soil microorganisms can derive ethylene from L-methionine (L-MET), while some rhizobacteria can hydrolyze 1-aminocyclopropane-1-carboxylate (ACC) due to their ACC-deaminase activity. In this study, three strains having either ACC-deaminase activity (Pseudomonas putida biotype A, A7), or the ability to produce ethylene from L-MET (Acinetobacter calcoaceticus, M9) or both (Pseudomonas fluorescens, AM3) were used for inoculation. The highly ethylene specific bioassay of a classical "triple" response in pea seedlings was used to investigate the effect of the inoculation with the rhizobacteria in the presence of 10 mM ACC or L-MET. The exogenous application of ACC had a concentration-dependent effect on the etiolated pea seedlings in creating the classical "triple" response. The inoculation with P. putida diluted the effect of ACC, which was most likely due to its ACC-deaminase activity. Similarly, the application of Co2+ reduced the ACC-imposed effect on etiolated pea seedlings. In contrast, the inoculation of A. calcoaceticus or P. fluorescens in the presence of L-MET caused a stronger classical "triple" response in etiolated pea seedlings; most likely by producing ethylene from L-MET. This is the first study, to our knowledge, reporting on the comparative effect of rhizobacteria capable of utilizing ACC vs L-MET on etiolated pea seedlings.     

Spectroscopic investigation on glutamic acid by Coulomb-attenuating and double hybrid density functional theory methods

This study deals with the identification of glutamic acid by means of quantum chemical approach. FT-IR, FT-Raman and UV–vis spectra were recorded in the region 4000–400, 4000–50 cm^? 1 and 200–600 nm, respectively. CAM-B3LYP/6-31G(d,p) and B2PLYP/6-31G(d,p) calculations were performed to obtain the optimised molecular structures, vibrational frequencies and corresponding vibrational assignment, thermodynamic properties and natural bonding orbital (NBO) analysis. The results show that the obtained optimised geometric parameters (bond lengths, bond angles and bond dihedrals) and vibrational frequencies were found to be in good agreement with the experimental results. The calculations of the electronic spectra were compared with the experimental ones. Furthermore, highest occupied molecular orbital and lowest unoccupied molecular orbital analyses and UV–vis spectral analysis were also performed to determine the energy band gaps and transition states. NBO analysis, calculated using density functional theory methods (CAM-B3LYP/6-31G(d,p) and B2PLYP/6-31G(d,p)), was induced to find inter-molecular atoms. ¹³C and ¹H NMR isotropic chemical shifts were calculated and the assignments made were compared with the ChemDraw Ultra values.