Karyotypes of two Antarctic fishes,Notothenia gibberifrons andNotothenia coriiceps neglecta

The chromosomes of two species of Antarctic fishes,Notothenia (Gobionotothen) gibberifrons andNotothenia (Notothenia) coriiceps neglecta, were prepared by the air-drying method at the Polish Antarctic Station “Henryk Arctowski” during the austral summer 1984–1985. ForN. (G.) gibberifrons the diploid number is2n = 46 consisting of 2 metacentric (m) pairs, 1 submetacentric (sm) pair and 20 telocentric (t) or subtelocentric (st) pairs. ForN. (N.) coriiceps neglecta the diploid number is 2n = 22 consisting of 9 m pairs, 1 sm pair and 1st pair. Some aspects of karyological evolution of these fishes are discussed.     

cis-Dominant, glutamine synthetase constitutive mutations of Escherichia coli independent of activation by the glnG and glnF products

Summary Mutants resistant to 80 M L-methionine-DL-sulfoximine (MS) were isolated on glucose-minimal 15 mM NH ₊ ⁴ medium plates from Escherichia coli cells which were hypersensitive to this concentration of the analogue by virtue of their harboring glnG mutations. MS-resistant mutants derived from strain MX902 carried, in addition to its glnG74::Tn5 allele, mutations tightly linked to glnA, as shown by P1-mediated transduction experiments. One particular allele, gln-76, which suppressed the MS-sensitivity conferred by glnG74::Tn5 but not its Ntr^– phenotype (inability to transport and utilize compounds such as arginine or proline as the only nitrogen sources), was shown to allow constitutive expression of glutamine synthetase in the absence not only of a functional glnG product but also of a functional glnF product. This behavior was found to be cis-dominant in complementation experiments with F'14 merogenotes. In an otherwise wild-type genetic background as in MX929 (gln-76 glnA ⁺ glnL⁺ glnG⁺ glnF⁺), however, normal activation, mediated by the glnG and glnF products was preferred over that mediated by gln-76.     

CO2-enriched atmosphere and supporting material impact the growth,morphophysiology and ultrastructure of in vitro Brazilian-ginseng [Pfaffia glomerata (Spreng.) Pedersen] plantlets

This study aimed to evaluate under photoautotrophic conditions the effect of CO₂-enriched atmosphere (360 or 1,000 μmol CO₂ mol^?1 air) combined with two substrate types (agar or Florialite^®) in vitro on plants of Pfaffia glomerata, an endangered medicinal species with promising applications in phytotherapy and phytomedicine. The effects of the treatments on the growth, stomatal density, Rubisco activity, carbon isotopic discrimination, metabolite accumulation, photosynthetic pigments and ultrastructural characteristics were investigated. After a 35-day cultivation period, the in vitro-growth of P. glomerata nodal segments under the different treatments resulted in plants with substantial differences in relation to their growth, photosynthetic pigments, stomatal density and leaf ultrastructural characteristics. The enrichment with CO₂ coupled with a porous substrate increased the growth of P. glomerata. The stomatal density in the abaxial epidermis more than doubled in response to the high CO₂ supply in both supporting types, whereas the Rubisco activity and activation state were both unresponsive to the treatments. Regardless of the CO₂ supply, the plants grown in agar displayed higher carbon isotope discrimination than their counterparts grown in Florialite^®. We propose that the long-term photosynthetic performance was improved using Florialite^® as a growth support in combination with a high CO₂ supply. No apparent signs of photosynthetic down-regulation could be found under elevated CO₂ conditions. The enrichment of in vitro atmospheres with CO₂ coupled with a porous substrate offers new possibilities for improving the growth and production on a commercial scale of high morphological and physiological quality Pfaffia plants.     

Bovine TWINKLE and mitochondrial ribosomal protein L43 genes are regulated by an evolutionary conserved bidirectional promoter

TWINKLE is a mitochondrial DNA helicase playing an important role in mitochondrial DNA replication. In human, mutations in this gene cause progressive external ophtalmoplegia and mitochondrial DNA depletion syndrome-7. TWINKLE is well conserved among multicellular eukaryotes and is believed to be a key regulator of mitochondrial DNA copy number in mammals.     

Modeling 3D Facial Shape from DNA

Human facial diversity is substantial, complex, and largely scientifically unexplained. We used spatially dense quasi-landmarks to measure face shape in population samples with mixed West African and European ancestry from three locations (United States, Brazil, and Cape Verde). Using bootstrapped response-based imputation modeling (BRIM), we uncover the relationships between facial variation and the effects of sex, genomic ancestry, and a subset of craniofacial candidate genes. The facial effects of these variables are summarized as response-based imputed predictor (RIP) variables, which are validated using self-reported sex, genomic ancestry, and observer-based facial ratings (femininity and proportional ancestry) and judgments (sex and population group). By jointly modeling sex, genomic ancestry, and genotype, the independent effects of particular alleles on facial features can be uncovered. Results on a set of 20 genes showing significant effects on facial features provide support for this approach as a novel means to identify genes affecting normal-range facial features and for approximating the appearance of a face from genetic markers.     

Thioredoxins in Redox Maintenance and Survival during Oxidative Stress of Bacteroides fragilis

The anaerobe Bacteroides fragilis is a gram-negative, opportunistic pathogen that is highly aerotolerant and can persist in aerobic environments for extended periods. In this study, the six B. fragilis thioredoxins (Trxs) were investigated to determine their role during oxidative stress. Phylogenetic analyses of Trx protein sequences indicated that four of the six Trxs (TrxA, TrxC, TrxD, and TrxF) belong to the M-type Trx class but were associated with two different M-type lineages. TrxE and TrxG were most closely associated to Y-type Trxs found primarily in cyanobacteria. Single and multiple trx gene deletions were generated to determine functional differences between the Trxs. The trxA gene was essential, but no anaerobic growth defects were observed for any other single trx deletion or for the ΔtrxC ΔtrxD::cfxA ΔtrxE ΔtrxF ΔtrxG quintuple mutant. Regulation of the trx genes was linked to the oxidative stress response, and all were induced by aerobic conditions. The ΔtrxC ΔtrxE ΔtrxF ΔtrxG and the ΔtrxC ΔtrxD::cfxA ΔtrxE ΔtrxF ΔtrxG multiple deletion strains were impaired during growth in oxidized media, but single trx gene mutants did not have a phenotype in this assay. TrxD was protective during exposure to the thiol oxidant diamide, and expression of trxD was induced by diamide. Diamide-induced expression of trxC, trxE, and trxF increased significantly in a trxD mutant strain, suggesting that there is some capacity for compensation in this complex Trx system. These data provide insight into the role of individual Trxs in the B. fragilis oxidative stress response.Protective mechanisms for dealing with oxidative stress are an integral part of any organism that lives in, or is exposed to, an aerobic environment. While aerobic organisms have developed robust systems to contend with the constant threat of destructive oxygen radicals, anaerobic organisms introduced to an aerobic environment are at an elevated risk for damage. Oxygen toxicity in anaerobes is a complex phenomenon involving many aspects of cellular physiology that are impaired as oxidative damage occurs. For example, aerobic exposure of the aerotolerant Bacteroides thetaiotaomicron inhibits growth, in part due to the oxidation of iron-sulfur clusters located within metabolic enzymes (30). To combat this problem, some anaerobic bacteria have evolved multifaceted strategies to manage the production and effects of reactive oxygen species (38). Bacteroides fragilis is a commensal anaerobe found in the human intestine, but it also is the most frequently isolated anaerobe from human infections (10). B. fragilis is unable to multiply in the presence of air (21% O₂); however, it is highly resistant to oxidative stress and can survive for extended periods in a fully aerobic environment. In this regard, B. fragilis is one of the most aerotolerant anaerobes known, and it is able to survive for at least 72 h in the presence of atmospheric oxygen. In contrast, intolerant anaerobes survive for less than 2 h in air (49). This remarkable resistance to oxidative stress is mediated by an oxidative stress response (OSR) which involves a wide array of genes activated during exposure to air or H₂O₂. An ever-growing set of genes and proteins that are induced in response to aerobic exposure have been discovered, and while the function of some have been deduced, many of their contributions to aerotolerance remain to be clarified (15, 36-38, 48). In this regard, a recent expression microarray showed that the B. fragilis thioredoxin (Trx) genes were induced by aerobic conditions, but their role in the OSR has not been adequately explored (48).Trxs are small redox-active proteins (∼12 kDa) found in all phylogenetic branches. Trxs contain a highly conserved Cys-X-X-Cys motif at their active sites, allowing for catalysis of thiol-disulfide reactions (1, 40). The reduction of Trxs is mediated by flavin adenine dinucleotide-dependent Trx reductases (TrxB) which convert oxidized Trxs to their free thiol forms (1). Since the discovery of their role in DNA synthesis and in maintenance of the reduced state of intracellular protein disulfides, Trxs have been shown to be involved in defense against oxidative stress (17). Trxs regenerate oxidatively damaged proteins, modulate the activity of redox stressors, and act as hydrogen donors for detoxification enzymes important during the OSR (7, 9, 25, 27, 28).Analysis of the B. fragilis genome revealed the presence of a single Trx reductase (TrxB) and six Trx homologs. This large repertoire of trx genes appears unusual compared to the typical smaller number of trx genes (two or three) found in other anaerobes (13, 19-21, 33, 42, 29). Previously, Rocha et al. (40) showed that the TrxB/Trx system is the primary thiol/disulfide redox system in B. fragilis; it has an important role in aerotolerance and is essential for survival in an in vivo mouse abscess model. These findings prompted us to propose that while TrxB is required for the function of the system overall, each Trx has important, specific roles in survival and defense against oxidative stress. In this study we present evidence that B. fragilis possesses a complex Trx system in which individual trx genes are differentially regulated but have some capacity to compensate for other trx genes under stress conditions. We also present evidence suggesting that TrxD has a major role in managing thiol oxidation and that trxA is an essential gene.     

Utility of six fungicides for selective isolation of Evlachovaea sp. and Tolypocladium cylindrosporum

The effects of the fungicides dodine, benomyl, thiabendazole, mancozeb, cupric sulfate, and copper oxychloride were examined in vitro upon germination and further development of Evlachovaea sp. and Tolypocladium cylindrosporum. Fungicidal activity depended on concentrations and varied among products, fungi and the strains tested. Depending on the fungicidal concentration, germination of conidia was induced but germlings produced neither mycelium nor new conidia. There was a good recovery of both Evlachovaea sp. and T. cylindrosporum from previously sterilized soils with fungicide-supplemented medium. Fungi were resistant to copper oxychloride up to 30 g/l, and this fungicide was found to have no utility for a selective medium. Minimal fungicide concentrations for successful isolations were 1 mg/l for benomyl, 200 mg/l for cupric sulfate, 50 mg/l for dodine, 100 mg/l for mancozeb, and 4 mg/l for thiabendazole. Thiabendazole, which is easy to obtain and can be used in low quantities, showed the greatest utility for a selective medium with these entomopathogenic fungi. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Sickness and Aggressive Behavior in Dominant and Subordinate Mice*

Sick animals show a set of organized behavioral changes (sickness behavior), which is the result of a motivational re‐organization of the behavior as a whole. Sickness behavior display can be influenced by the social context. In this work, we sought to investigate the regulation of sickness behavior within a pair of mice in the presence of an intruder mouse. Dominant and subordinate mice were treated with the bacterial endotoxin lipopolysaccharide (LPS) and were challenged with the presence of an intruder mouse. LPS effects depended on ranking and social context. Even though dominant mice displayed more agonistic interaction towards the intruder, subordinate mice displayed agonistic behavior towards the intruder when their dominant companion was treated with LPS. The results show that, not only sickness behavior is differentially expressed among different social ranks, but also that sickness behavior is related to different reactions among surrounding animals. These data are relevant for a biological approach to the relation between sickness behavior and social behavior.