Pathotypic variation of Xanthomonas oryzae pv. oryzae in Bangladesh

Bacterial Blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo), a destructive disease of rice. Altogether, 96 isolates of Xoo were collected from 19 rice growing districts of Bangladesh in irrigated and rainfed seasons during 2014 to assess pathotypic variation. Pathotypic analyses on a set of 12 Near Isogenic Lines (NILs) of rice containing resistance genes viz. Xa1, Xa2, Xa3, Xa4, Xa5, Xa7, Xa8, Xa10, Xa11, Xa13, Xa14 and Xa21 and two check varieties IR24 and TN1 by leaf clip-inoculation technique. A total of 24 pathotypes were identified based on their virulence patterns on NILs tested. Among these, pathotypes VII, XII, and XIV considered as major, containing maximum number of isolates, (9.38% each) frequently distributed in North to Mid-Eastern districts of Bangladesh. Most virulent pathotype I recorded from Habiganj and Brahmanbaria. This pathotypic variation explained the pathogenic relatedness of X. oryzae pv. oryzae populations from diverse geographic areas in Bangladesh.     

An Archaeal Aerotaxis Transducer Combines Subunit I Core Structures of Eukaryotic Cytochrome c Oxidase and Eubacterial Methyl-Accepting Chemotaxis Proteins

Signal transduction in the archaeon Halobacterium salinarum is mediated by three distinct subfamilies of transducer proteins. Here we report the complete htrVIII gene sequence and present analysis of the encoded primary structure and its functional features. HtrVIII is a 642-amino-acid protein and belongs to halobacterial transducer subfamily B. At the N terminus, the protein contains six transmembrane segments that exhibit homology to the heme-binding sites of the eukaryotic cytochrome c oxidase. The C-terminal domain has high homology with the eubacterial methyl-accepting chemotaxis protein. The HtrVIII protein mediates aerotaxis: a strain with a deletion of the htrVIII gene loses aerotaxis, while an overproducing strain exhibits stronger aerotaxis. We also demonstrate that HtrVIII is a methyl-accepting protein and demethylates during the aerotaxis response.     

Detailed NMR Analysis of the Heme-Protein Interactions in Component IV Glycera dibranchiata Monomeric Hemoglobin-CO

Complete 13C, 15N, and 1H resonance assignments have been obtained for the recombinant, ferrous CO-ligated form of component IV monomeric hemoglobin from Glycera dibranchiata. This 15642 Da myoglobin-like protein contains a large number of glycine and alanine residues (47) and a heme prosthetic group. Coupling constant information has allowed the determination of 1 and 2 torsion angles, backbone angles, as well as 43 of 81 possible assignments to H2/3 pairs. The 13C, 13C, 13C, and 1H assignments yield a consensus chemical shift index (CSI) that, in combination with NOE information and backbone torsion angles, defines seven distinct helical regions for the protein's global architecture. Discrepancies between the CSI and NOE/3JHNH-based secondary structure definitions have been attributed to heme ring current shifts on the basis of calculations from a model structure [Alam et al. (1994) J. Protein Chem., 13, 151-164]. The agreement can be improved by correcting the 1H chemical shifts for the ring current contributions. Because the holoprotein was assembled from isotopically enriched globin and natural isotope-abundance heme, data from 13C-filtered/13C-edited and 13C-filtered/13C-filtered 2D NOESY experiments could be used to determine complete heme proton assignments and to position the heme within the protein. The results confirm the unusual presence of Phe31(B10) and Leu58(E7) side chains near the heme ligand binding site which may alter the polarity and steric environment and thus the functional properties of this protein.     

Germ line transmission and expression of alacZ containing transgene in tilapia (Oreochromis niloticus)

Transgenic tilapia were produced using a carp -actinlacZ gene construct and the transmission of the transgene to F₁ progeny was followed. Of 36 founder fish analysed, 9 (25%) were found to be transgenic in at least one tissue and two of these were found to transmit the transgene to progeny. One male produced only three out of 28 transgene DNA positive progeny (10.7%) but none of these were found to express the transgene. The other male produced 243 out of 1601 (15.2%)lacZ expressing embryos; 40 of these were analysed by Southern blotting and all were found to be positive for the presence of the transgene but revealed two different patterns of transgene arrangement. Three different expression patterns were also observed and presumed to be a result of multiple integration events and resulting position effects.     

Relation between maternal haemoglobin concentration and birth weight in different ethnic groups.

OBJECTIVE--To assess the relation of the lowest haemoglobin concentration in pregnancy with birth weight and the rates of low birth weight and preterm delivery in different ethnic groups. DESIGN--Retrospective analysis of 153,602 pregnancies with ethnic group and birth weight recorded on a regional pregnancy database during 1988-91. The haemoglobin measurement used was the lowest recorded during pregnancy. SETTING--North West Thames region. SUBJECTS--115,262 white women, 22,206 Indo-Pakistanis, 4570 Afro-Caribbeans, 2642 mediterraneans, 3905 black Africans, 2351 orientals, and 2666 others. MAIN OUTCOME MEASURES--Birth weight and rates of low birth weight (< 2500 g) and preterm delivery (< 37 completed weeks). RESULTS--Maximum mean birth weight in white women was achieved with a lowest haemoglobin concentration in pregnancy of 85-95 g/l; the lowest incidence of low birth weight and preterm labour occurred with a lowest haemoglobin of 95-105 g/l. A similar pattern occurred in all ethnic groups. CONCLUSIONS--The magnitude of the fall in haemoglobin concentration in pregnancy is related to birth weight; failure of the haemoglobin concentration to fall below 105 g/l indicates an increased risk of low birth weight and preterm delivery. This phenomenon is seen in all ethnic groups. Some ethnic groups have higher rates of low birth weight and preterm delivery than white women, and they also have higher rates of low haemoglobin concentrations. This increased rate of "anaemia," however, does not account for their higher rates of low birth weight, which occurs at all haemoglobin concentrations.     

A mitochondrial import factor purified from rat liver cytosol is an ATP-dependent conformational modulator for precursor proteins.

Rat liver cytosol contained an activity that stimulated the import of wheat germ lysate-synthesized precursor proteins into mitochondria. The activity was purified 10,000-fold from the cytosol as a homogeneous heterodimeric protein. This protein (termed mitochondrial import stimulation factor or MSF) stimulated the binding and import of mitochondrial precursor proteins. MSF was also found to recognize the presequence portion of mitochondrial precursors and catalyze the depolymerization and unfolding of in vitro synthesized mitochondrial precursor proteins in an ATP-dependent manner; in this connection, MSF exhibited ATPase activity depending on the important-incompetent mitochondrial precursor protein. The mitochondrial binding and import-stimulating activities were strongly inhibited by the pretreatment of MSF with NEM, whereas the ATP-dependent depolymerization activity was insensitive to the NEM treatment, suggesting that the process subsequent to the unfolding was inhibited with the NEM treatment. We conclude that MSF is a multifunctional cytoplasmic chaperone specific for mitochondrial protein import.     

Pathology of naturally occurring toxoplasma abortion and neonatal mortality in Black Bengal goat

Characteristic pathological lesions in Black Bengal goat abortions due to naturally occurring toxoplasmosis consist of focal inflammation of the placenta. No specific macroscopic changes were marked in other organs of the fetuses. The main microscopic changes were focal or diffuse infiltrations with round cells in the liver, brain and heart. These lesions were more common in the brain than in other organs. Toxoplasma organisms were demonstrated in these organs as single trophozoites or within the cyst. No characteristic gross or histological changes were demonstrated in lymph nodes, spleen, lung and kidney. These results could be useful for histopathological diagnosis of toxoplamosis in Black Bengal goats.     

Presence of four toxins in red tide infested clams and cultured Gonyaulax tamarensis cells.

Four toxins have been isolated by Sephadex G-15 and high pressure ion exchange chromatography from the soft shell clams, $\text{Mya arenaria}$, which were collected during 1972 and 1974 red tide outbreaks on the New England coast. One of the toxins was saxitoxin and the rest seem to be new toxins. The same toxins were isolated from the extract of cultured $\text{Gonyaulax tamarensis}$.     

Stimulation of osteoclastic bone resorption by hydrogen peroxide.

The molecular mechanisms underlying the pathophysiology of bone destruction still remain poorly understood. We have found that hydrogen peroxide (H2O2), a reactive oxygen species (ROS), is a potent stimulator of osteoclastic bone resorption and cell motility. A marked enhancement of bone resorption was noted when rat osteoclasts, cultured on devitalised bovine cortical bone, were exposed to 10 nM [H2O2]. Apart from exposing osteoclasts to a low extracellular pH, which is known to enhance osteoclastic bone resorption, we provide first evidence for a molecule that stimulates osteoclastic bone resorption in osteoclast cultures that do not respond to parathyroid hormone and 1, 25 dihydroxyvitamin D3. We envisage that both basic biological and practical clinical implications may eventually follow from these studies.