The multi-locus H-2D w16 region has an organization distinct from the D d region

Genomic DNA blot analyses using probes derived from the BALB/c 3 flanking region of the L ^d gene (L ^d 3 fl-C) and from near the BALB/c D3 ^d gene (50.2A) indicate that the B10.GAA37 mouse strain has a multi-locus D (D ^w16) region distinct from the five-gene organization observed in the D ^d and D ^q regions. To isolate the D ^w16 region class I genes, a genomic B10. GAA37-EMBL3 library was generated and screened with probes that preferentially hybridize to K and D region class I genes. Hybridization analyses of the isolated clones with L ^d derived oligonucleotide probes suggested that one of the clones contained the L ^w16 gene, whereas several other clones contained the L ^w16 gene. The sequence of the D ^w16 gene is most similar to that of the D ^p gene, particularly in the 3 half. Furthermore, the L ^w16 gene is quite similar in the 5 half and virtually identical in the 3 half to the L ^d gene, indicating that L ^w16, but not D ^w16, is a member of the L ^d gene family. Collectively, these data suggest that, through a D region recombination event, the novel D ^w16 region may have been assembled from primordial counterparts of the D ^p and L ^d genes.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number M60774-M60776, and M62759.     

Morphological and mitochondrial DNA variation revealed an undescribed lineage under the genus Sperata (Bagridae) in Bangladesh

Catfishes Sperata are popular, known for its taste and nutritional value, and are found naturally in wide variety of freshwaters in South Asia. The taxonomy of Sperata spp., sampled from Hakaluki Haor in Bangladesh, was re‐evaluated based on morphological variation and DNA barcoding. The collective variation in morphometric characters and mitochondrial DNA revealed an undescribed old and well‐separated lineage under the genus Sperata along with two previously known Sperata aor and Sperata seenghala in Bangladesh. Analyses of morphological traits suggested significant differentiation among Sperata species. The variation in mitochondrial DNA supported the distinct lineage and taxonomical discrimination. Sperata aor diverged earlier from the new lineage and Sperata seenghala with a divergence of 5.39 (CI: 3.91–7.19) Mya (PP > 90). Sperata seenghala and the new lineage shared a most recent common ancestry, which diverged from each other around 3.41 (CI: 2.24–4.62) Mya (PP > 90). Thus, the newly identified lineage could be a subspecies of S. seenghala or even a species under the genus Sperata. The information of the study will be useful for conservation, sustainable management and selective breeding of the putative species, including previously reported S. aor and S. seenghala in Bangladesh.     

Rubrioxytricha guamensis nov. spec. (Ciliophora,Spirotricha), a Novel Hypotrich Ciliate from Guam (United States), Micronesia

The oxytrichid ciliate Rubrioxytricha guamensis nov. spec. isolated from water samples collected from a small freshwater pond near the Hagåtña River in Hagåtña, Guam (United States territory), Micronesia, was investigated, using live observation and protargol impregnation. The morphology, ontogenesis, and molecular phylogeny inferred from the small‐subunit rRNA gene sequences were studied. The new species is mainly characterized by a cell size of about 100 × 35 μm in vivo, two elongate ellipsoidal macronuclear nodules and two micronuclei, a single contractile vacuole, a colorless cytoplasm, yellowish cortical granules, arranged in short rows and in small groups, an adoral zone occupying about 34% of body length and comprising 27 membranelles on average, about 27 cirri each in the right and left marginal rows, 18 frontoventral transverse cirri, four dorsal kineties including one dorsomarginal row, and one or two caudal cirri at the posterior end of dorsal kinety 3. The ontogenesis of the new species is similar to that of Rubrioxytricha indica Naqvi et al., 2006. Phylogenetic analyses based on SSU rRNA gene sequences consistently place the new species within the family Oxytrichidae Ehrenberg, 1838, where it clustered with other Rubrioxytricha species, viz., R. tsinlingensis, R. ferruginea, and R. haematoplasma.     

The proliferation of fungal hyphae in soils supporting mycorrhizal and non-mycorrhizal plants

This study investigated the impact of mycorrhizal plants, non-mycorrhizal plants and soil organic matter on the relative abundance of soil hyphae perceived to belong to indigenous arbuscular mycorrhizal (AM) plants. The mycorrhizal plants corn (Zea mays L.) and barley (Hordeum vulgare L.) and a non-mycorrhizal plant, canola (Brassica napus L.), were grown in unsterilized soil in pots inoculated with mycorrhizal corn root fragments. The abundance of hyphae was measured after 5 weeks and the response of fungal growth to the addition of corn residues in the absence of plants was assessed. The abundance of hyphae was higher in the presence of the mycorrhizal plants than in the other treatments. AM hyphae present under mycorrhizal plants accounted for more than 83% of the measured hyphae. The levels of root colonization of 32% in corn and 27% in barley confirmed the mycorrhizal status of the experimental plants. Only a few points of entry were observed in canola, the non-host plant. The percentage of mycorrhizal colonization was positively related (R ²?=?0.85) to the abundance of soil hyphae, indicating that AM hyphae were the major component of the soil hyphae in the presence of mycorrhizal plants in this study.     

Burkholderia pseudomallei: Its Detection in Soil and Seroprevalence in Bangladesh

Background

Melioidosis, caused by Burkholderia pseudomallei, is an endemic disease in Bangladesh. No systematic study has yet been done to detect the environmental source of the organism and its true extent in Bangladesh. The present study attempted to isolate B. pseudomallei in soil samples and to determine its seroprevalence in several districts in Bangladesh.

Methodology and Results

Soil samples were collected from rural areas of four districts of Bangladesh from where culture confirmed melioidosis cases were detected earlier. Multiple soil samples, collected from 5–7 sampling points of 3–5 sites of each district, were cultured in Ashdown selective media. Suspected colonies of B. pseudomallei were identified by biochemical and serological test, and by polymerase chain reaction (PCR) using 16s rRNA specific primers. Blood samples were collected from 940 healthy individuals of four districts to determine anti- B. pseudomallei IgG antibody levels by indirect enzyme linked immunosorbent assay (ELISA) using sonicated crude antigen. Out of 179 soil samples, B. pseudomallei was isolated from two samples of Gazipur district which is located 58 km north of capital Dhaka city. Both the isolates were phenotypically identical, arabinose negative and showed specific 550bp band in PCR. Out of 940 blood samples, anti- B. pseudomallei IgG antibody, higher than the cut-off value (>0.8), was detected in 21.5% individuals. Seropositivity rate was 22.6%-30.8% in three districts from where melioidosis cases were detected earlier, compared to 9.8% in a district where no melioidosis case was either detected or reported (p<0.01). Seropositivity increased with the advancement of age from 5.3% to 30.4% among individuals aged 1–10 years and > 50 years respectively. The seropositivity rates were 26.0% and 20.6% in male and female respectively, while it was 20–27% among different occupational groups. No significant association was observed with gender (χ2 = 3.441, p = 0.064) or any occupational group (χ² = 3.835, p = 0.280).

Conclusion

This is the first study demonstrating the presence of B. pseudomallei in the environmental (soil) samples of Bangladesh. It also suggested that a large proportion of people, residing in these districts, were exposed to the organism.     

Luteolytic influence of intrauterine dead embryos in the early pregnant rat

The present investigation was an endeavour to study if annihilation of embryos in the uterus of the rat before the establishment of placental luteotropic functions has any influence on corpus luteal function, and, if there is any, whether it is local or systemic. The responsibility of pregnancy maintenance was imposed on a single ovary by performing unilateral ovariectomy after implantation (on Day 5 postcoitum). The implantation sites in one uterine horn, either ipsilateral or contralateral to the remaining ovary, were selectively destroyed by injecting 0.1 ml of sterile normal saline to that particular horn only, and the peripheral progesterone level and viability of the embryos in the untreated horn, which depended on the functions of the remaining ovary, were examined. Selective killing of embryos in the uterine horn of the ovariectomized side did not exert any influence on the fetal viability in the untreated horn ( nonovariectomized side) and the peripheral progesterone level also remained statistically unaffected. On the contrary, induction of fetal resorptions in the uterine horn of the intact side produced a significant fall in the peripheral level of progesterone and induced resorption of embryos of the ovariectomized side also. The latter could significantly be prevented by simultaneous administration of exogenous progesterone, indicating luteolysis as the major, if not sole, factor responsible for fetal resorption in the untreated horn. The luteolytic effect was attributed neither to saline itself, nor to the distension of the uterine horn caused by saline injection. Luteolytic factors from the dead embryo-bearing horn which act locally on the adjacent ovary only, are discussed.     

Bacterial overgrowth by indigenous microflora in the phytohemagglutinin-fed rat

Phytohemagglutinin lectin (PHA) derived from red kidney bean (Phaseolus vulgaris) causes bacterial and protozoal colonization of the rat small intestine. To provide additional insights into this phenomenon we have studied the time course and population dynamics of microbial colonization of the major aerobe--facultative anaerobe groups which characterize this microflora. Compared with controls, PHA caused proliferation of a consistent adherent microbial flora in the jejunum (P less than 0.01). The predominant bacteria identified were Escherichia coli. a Streptococcal sp., and Lactobacillus. Escherichia coli isolates expressed no predominant serotype or fimbriae; none elaborated heat-labile or heat-stable toxin. Both E. coli and Streptococcal sp. populations increased within 24 h of PHA feeding and were sustained during further exposure to PHA (P less than 0.05). On reversion to a control diet, coliform counts fell progressively within 24-48 h and continued to decline, whereas gram-positive rod and coccus flora became the more prominent colonizers through days 1 to 4 of the reversion.