Roles of Subunit NuoK (ND4L) in the Energy-transducing Mechanism of Escherichia coli NDH-1 (NADH:Quinone Oxidoreductase)

The bacterial H⁺-translocating NADH:quinone oxidoreductase (NDH-1) catalyzes electron transfer from NADH to quinone coupled with proton pumping across the cytoplasmic membrane. The NuoK subunit (counterpart of the mitochondrial ND4L subunit) is one of the seven hydrophobic subunits in the membrane domain and bears three transmembrane segments (TM1–3). Two glutamic residues located in the adjacent transmembrane helices of NuoK are important for the energy coupled activity of NDH-1. In particular, mutation of the highly conserved carboxyl residue (_KGlu-36 in TM2) to Ala led to a complete loss of the NDH-1 activities. Mutation of the second conserved carboxyl residue (_KGlu-72 in TM3) moderately reduced the activities. To clarify the contribution of NuoK to the mechanism of proton translocation, we relocated these two conserved residues. When we shifted _KGlu-36 along TM2 to positions 32, 38, 39, and 40, the mutants largely retained energy transducing NDH-1 activities. According to the recent structural information, these positions are located in the vicinity of _KGlu-36, present in the same helix phase, in an immediately before and after helix turn. In an earlier study, a double mutation of two arginine residues located in a short cytoplasmic loop between TM1 and TM2 (loop-1) showed a drastic effect on energy transducing activities. Therefore, the importance of this cytosolic loop of NuoK (_KArg-25, _KArg-26, and _KAsn-27) for the energy transducing activities was extensively studied. The probable roles of subunit NuoK in the energy transducing mechanism of NDH-1 are discussed.     

A recombinant foot-and-mouth disease virus antigen inhibits DNA replication and triggers the SOS response in Escherichia coli

Abstract The 3D gene of foot-and-mouth disease virus encodes the viral RNA dependent RNA polymerase, also called virus infection associated (VIA) antigen, which is the most important serological marker of virus infection. This 3D gene from a serotype Cl virus has been cloned and overexpressed in Escherichia coli under the control of the strong lambda lytic promoters. The resulting 51 kDa recombinant protein has been shown to be immunoreactive with sera from infected animals. After induction of gene expression, an immediate and dramatic arrest of cell DNA synthesis occurs, similar to that produced by genotoxic doses of the drug mitomycin C. This effect does not occur during the production of either a truncated VIA antigen or other related and non-related viral proteins. The inhibition of DNA replication results in a subsequent induction of the host SOS DNA-repair response and in an increase of the mutation frequency in the surviving cells.     

Prioritizing Tiger Conservation through Landscape Genetics and Habitat Linkages

Even with global support for tiger (Panthera tigris) conservation their survival is threatened by poaching, habitat loss and isolation. Currently about 3,000 wild tigers persist in small fragmented populations within seven percent of their historic range. Identifying and securing habitat linkages that connect source populations for maintaining landscape-level gene flow is an important long-term conservation strategy for endangered carnivores. However, habitat corridors that link regional tiger populations are often lost to development projects due to lack of objective evidence on their importance. Here, we use individual based genetic analysis in combination with landscape permeability models to identify and prioritize movement corridors across seven tiger populations within the Central Indian Landscape. By using a panel of 11 microsatellites we identified 169 individual tigers from 587 scat and 17 tissue samples. We detected four genetic clusters within Central India with limited gene flow among three of them. Bayesian and likelihood analyses identified 17 tigers as having recent immigrant ancestry. Spatially explicit tiger occupancy obtained from extensive landscape-scale surveys across 76,913 km² of forest habitat was found to be only 21,290 km². After accounting for detection bias, the covariates that best explained tiger occupancy were large, remote, dense forest patches; large ungulate abundance, and low human footprint. We used tiger occupancy probability to parameterize habitat permeability for modeling habitat linkages using least-cost and circuit theory pathway analyses. Pairwise genetic differences (F _ST) between populations were better explained by modeled linkage costs (r>0.5, p<0.05) compared to Euclidean distances, which was in consonance with observed habitat fragmentation. The results of our study highlight that many corridors may still be functional as there is evidence of contemporary migration. Conservation efforts should provide legal status to corridors, use smart green infrastructure to mitigate development impacts, and restore habitats where connectivity has been lost.     

Association of four isozyme loci with a reciprocal translocation between 1R/4R chromosomes in cultivated rye (Secale cereale L.)

Summary The progeny of four crosses between a structural heterozygote for a reciprocal translocation and a homozygote for the standard chromosome arrangement were analyzed in rye (Secale cereale L. cv Ailés) for the electrophoretic patterns of eight different leaf and endosperm isozymes and also for the meiotic configuration at metaphase I. The Pgi-1, 6-Pgd-2 and Mdh-1 loci are linked to each other and also to the reciprocal translocation. These loci have been located on chromosome 1R. The Mdh-1 locus is located in the interstitial segment of chromosome 1R, between the centromere and the breakpoint. The Pgm-1 locus has been located on chromosome arm 4RS and is linked to Pgi-1, 6-Pgd-2, Mdh-1 and the reciprocal translocation. The estimated distance between the Pgm-1 locus and the centromere is 14.98 ± 2.27 cM. Therefore, the reciprocal translocation involves the 1R and 4R chromosomes. Other linked loci detected have been Mdh-2b and Est-2 (7.40 ± 2.90 cM) and Got-3 and Est-2 (5.62 ± 3.07 cM). These three last loci are located on chromosome 3R and their order most probably is Mdh-2b — Est-2 — Got-3.     

Thamnobryum subserratum and T. subseriatum (Musci) in Asia

A review of the nomenclatural history ofThamnobryum subserratum andThamnobryum subseriatum shows that the former, which ranges widely from the Himalayas to Southeast Asia, has been misrepresented in the literature asThamnobryum “subseriatum,” and that the latter, which appears to be a Japanese endemic, has been called a superfluous name,Thamnobryum sandei. A new combination,Thamnobryum subseriatum (Mitt. ex Sande Lac.) Tan, is proposed for the Japanese endemic and its lectotype hereby designated. In addition, morphological differences between the two taxa are discussed.     

The problem of the acts duration measurement in relation to the “focal-animal” technique of behavioral recording

The focal-animal technique assumes the continuous recording of the behavior of an individual during a certain time interval. The length of this interval (sampling unit) can be problematic when estimating the duration of behavioral acts. Two acts from the behavioral repertoire of the ant Leptothorax fuenteiwere focused on in this work at different ranges of temporal scales. Analyzing these acts we show the possibility of existence of a sampling artifact, in such a way that the estimates of the durations of the acts would be forced to depend upon the length of the sampling unit that is being used.     

Guaianolides and lignans from Centaurea solstitialis subs Schouwii

Aerial parts of Centaurea solstitialis subs schouwii afforded the guaianolides cynaropicrin and aguerin B and the lignans arctigenin and matairesinol. The structure of a third guaianolide previously found also in Centaurea behen was revised.     

Biochemical evidence of a translocation between 6 RL/7 RL chromosome arms in rye (Secale cereale L.). A genetic map of 6R chromosome

Summary The segregation of different isozymic loci was investigated in backcrosses and F₂s in rye. The leucin aminopeptidase-1 (Lap-1), Aconitase-1 (Aco-1), Esterase-6 (Est-6), Esterase-8 (Est-8), and Endopeptidase-1 (Ep-1) loci were linked. The Aco-1, Est-6, and Est-8 loci have been previously located on the 6RL chromosome arm. The Lap-1 locus has been located on the 6RS chromosome arm. The results favor the gene order: Lap-1... (centromere)... Aco-1... Est-8... Est-6... Ep-1. The isoelectric focusing separations of aqueous extracts from mature embryo tissue of wheat-rye addition and substitution lines involving the chromosomes of cereal rye Secale cereale L. confirmed the gene location of locus Ep-1 on the 6RL chromosome arm. Screening of wheat-rye addition lines involving the chromosomes of Secale montanum revealed that Ep-1 locus is not located on chromosome 6R of S. montanum. These results are the first biochemical evidence of the translocation between chromosome arms 6RL/7RL in the evolution of S. cereale from S. montanum.     

Changes in whole body concentrations of thyroid hormones and cortisol in metamorphosing conger eel

Summary To clarify the hormonal regulation of metamorphosis of the conger eel (Conger myriaster), changes in whole body concentrations of thyroid hormones, thyroxine (T₄) and triiodothyronine (T₃), and cortisol during metamorphosis were examined, as well as the changes in the histological activity of the thyroid gland. In larvae before metamorphosis, T₄ and T₃ levels were less than 5 and 0.15 ng·g^-1 respectively. Levels of T₄ increased to about 30 ng·g^-1 during early metamorphosis, and decreased subsequently. Levels of T₃ increased gradually in early metamorphosis, and then increased abruptly to about 2.0 ng·g^-1 in late metamorphosis. Before metamorphosis, cortisol levels of the leptocephali less than 11 cm in total length were greater than 200 ng·g^-1. Cortisol levels decreased rapidly in larger premetamorphic leptocephali, and low levels were maintained throughout the metamorphic period. Histological observation revealed an activation of the thyroid gland in early metamorphosis; thyroid follicle epithelial cells became columnar and their nuclei larger. Active uptake of colloid by these cells and intensive vascularization of the gland were also observed. By the end of metamorphosis, follicle epithelial cells became squamous, indicating a low level of glandular activity. These results suggest that thyroid hormone plays an important role in regulation of conger eel metamorphosis.Abbreviations AL anal length - TL total length - T ₃ triiodothyronine - T ₄ thyroxine     

A map of barley chromosome 2 using isozymic and morphological markers

The F₂ progeny of a cross between a chromosome 2 multiple marker stock and an adapted cultivar of barley were analyzed for four morphological markers and electrophoretic patterns of eight leaf isozymes. TheIdh-2 locus was linked to thePer-5 locus (27.96±5.07 cM) and to thee locus (10.26±3.13 cM). Also, thePer-5 ande loci were located on the short arm of chromosome 2. In additionIdh-2 was also located on barley chromosome 2 and was linked to thev locus (13.18±3.56 cM), which is located on the long arm of chromosome 2. Two other marker genes,li andwst,,B, were linked (26.50±5.24 cM) on chromosome 2 but segregate independently of the other loci evaluated. This project was supported by funds from the U.S.-Spain Joint Committee for Scientific and Technological Cooperation.