Coexistence of arbuscular mycorrhizae and dark septate endophytic fungi in an undisturbed and a disturbed site of an arid ecosystem

Effect of disturbance on root colonization and vertical distribution of arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) was investigated at two adjacent sites of Lal Suhanra Biosphere Reserve, Pakistan. Disturbance clearly affected AMF and DSE colonization, vertical distribution of AMF and plant community structure. Mean colonization of AMF and DSE was slightly less at the disturbed site. Average spore densities, diversity and richness of AMF and DSE were higher at the undisturbed site. A study of the vertical distribution of AMF associated with the five plant species most common to each study site indicated that beside AMF and DSE colonization disturbance may affect AMF species composition. Correlation of AMF with DSE is also discussed.     

Bacterial reduction of hexavalent molybdenum to molybdenum blue

A bacterium that was able to tolerate and reduce as high as 50 mM of sodium molybdate to molybdenum blue has been isolated from a metal recycling ground. The isolate was tentatively identified as Serratia sp. strain Dr.Y8 based on the carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. ANOVA analysis showed that isolate Dr.Y8 produced significantly higher (P < 0.05) amount of Mo-blue with 3, 5.1 and 11.3 times more molybdenum blue than previously isolated molybdenum reducers such as Serratia marcescens strain Dr.Y6, E. coli K12 and E. cloacae strain 48, respectively. Its molybdate reduction characteristics were studied in this work. Electron donor sources such as sucrose, mannitol, fructose, glucose and starch supported molybdate reduction. The optimum phosphate, pH and temperature that supported molybdate reduction were 5 mM, pH 6.0 and 37°C, respectively. The molybdenum blue produced from cellular reduction exhibited a unique absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. Metal ions such as chromium, silver, copper and mercury resulted in approximately 61, 57, 80, and 69% inhibition of the molybdenum-reducing activity at 1 mM, respectively. The reduction characteristics of strain Dr.Y8 suggest that it would be useful in future molybdenum bioremediation.     

Respiratory Viruses Associated Hospitalization among Children Aged <5 Years in Bangladesh: 2010-2014

Background

We combined hospital-based surveillance and health utilization survey data to estimate the incidence of respiratory viral infections associated hospitalization among children aged < 5 years in Bangladesh.

Methods

Surveillance physicians collected respiratory specimens from children aged <5 years hospitalized with respiratory illness and residing in the primary hospital catchment areas. We tested respiratory specimens for respiratory syncytial virus, parainfluenza viruses, human metapneumovirus, influenza, adenovirus and rhinoviruses using rRT-PCR. During 2013, we conducted a health utilization survey in the primary catchment areas of the hospitals to determine the proportion of all hospitalizations for respiratory illness among children aged <5 years at the surveillance hospitals during the preceding 12 months. We estimated the respiratory virus-specific incidence of hospitalization by dividing the estimated number of hospitalized children with a laboratory confirmed infection with a respiratory virus by the population aged <5 years of the catchment areas and adjusted for the proportion of children who were hospitalized at the surveillance hospitals.

Results

We estimated that the annual incidence per 1000 children (95% CI) of all cause associated respiratory hospitalization was 11.5 (10–12). The incidences per 1000 children (95% CI) per year for respiratory syncytial virus, parainfluenza, adenovirus, human metapneumovirus and influenza infections were 3(2–3), 0.5(0.4–0.8), 0.4 (0.3–0.6), 0.4 (0.3–0.6), and 0.4 (0.3–0.6) respectively. The incidences per 1000 children (95%CI) of rhinovirus-associated infections among hospitalized children were 5 (3–7), 2 (1–3), 1 (0.6–2), and 3 (2–4) in 2010, 2011, 2012 and 2013, respectively.

Conclusion

Our data suggest that respiratory viruses are associated with a substantial burden of hospitalization in children aged <5 years in Bangladesh.     

Compliance with diphtheria,tetanus, and pertussis immunisation in Bangladesh: factors identifying high risk groups.

OBJECTIVE--To evaluate factors associated with non-compliance with having second vaccination against diphtheria, tetanus, and pertussis in a treatment centre in Dhaka to determine which children were most at risk of not completing immunisation. DESIGN--Cohort study of infants given first dose of the vaccine and followed up six weeks later to ascertain compliance with having second dose. Factors associated with non-compliance were evaluated. SETTING--Dhaka treatment centre of the International Centre for Diarrhoeal Disease Research, Bangladesh. SUBJECTS--136 unimmunised children aged 6 weeks to 23 months who lived within reach of the treatment centre. At time of the six week follow up 16 of the children could not be traced and seven had died. INTERVENTIONS--All children received their first dose of the vaccine. In each case health education workers had informed the mother about the value of immunisation, and she was given clear instructions to bring the child back after four weeks for the second dose. MAIN OUTCOME MEASURE--Rate of non-compliance with advice to return child for second vaccination. RESULTS--46 of 113 children (41%) received the second dose of the vaccine. Factors most closely associated with mothers'' failure to comply with the second dose were lack of education and low income. Children whose mothers knew most about immunisation at first interview were more likely to have their second dose. CONCLUSIONS--Preventive health care services such as immunisation are appropriately offered in treatment centres, but compliance among children varies with socioeconomic status and mother''s education. Further research should be aimed at ways to make health education more effective among uneducated parents.     

A Technique for Quick Fixation of Whole Drosophila and Other Small Insects for Scanning Electron Microscopy

A procedure for fixing small insects in natural postures for scanning electron microscopy is reported. Anesthetized insects are partially restrained using a depression slide and a coverslip while preliminary fixation is carried out and wings and legs are positioned with a fine brush. Following this, fixation is completed and the insect is prepared for scanning electron microscopy by essentially standard procedures, which may include critical point drying. Figures illustrate, however, that critical point drying is not necessary for more rigid parts of the exoskeleton. Use of this procedure assures naturally disposed parts even when only a single specimen is available.     

一株碱性淀粉酶产生菌Bacillus flexus XJU-3的分离鉴定及酶学特性分析

[目的]从新疆石河子市一处碱性工业污水(pH11.0)分离﹑鉴定高产碱性淀粉酶菌株,并对其所产酶酶学特性进行研究.[方法]在碱性淀粉酶分离培养基上对所分离菌株进行筛选,分离到一株高产碱性淀粉酶菌株,并将其编号XJU-3.应用生理生化试验,脂肪酸含量,16S rDNA序列以及(G C) mol%含量等方法对菌株进行鉴定,同时对XJU-3所产碱性淀粉酶的生物学特性进行研究.[结果] XJU-3可在pH4.0～12.5的LB培养基上生长,最适生长温度37℃.16S rDNA序列构建的系统进化树表明XJU-3与Bacillus flexus类聚在一起,且序列同源性为99%.该菌产生的淀粉酶最适pH10.0,最适温度40℃,且在pH9.0～13.0内有较高活性和稳定性.Co2 和Mg2 能明显提高酶的活性.[结论] XJU-3被鉴定为Bacillus flexus,由于XJU-3与B. flexus DSM 1320T在尿素水解和优势脂肪酸含量上有差异,且具有宽范围pH耐受性,因此XJU-3被认为是B.flexus的一个新菌株.XJU-3所产的碱性淀粉酶酶学特性良好,具有极大的工业应用潜力.     

Substantial genetic divergence and lack of recent gene flow support cryptic speciation in a colour polymorphic bumble bee (Bombus bifarius) species complex

Phenotypic polymorphism can constitute an inherent challenge for species delimitation. This issue is exemplified in bumble bees (Bombus), where species can exhibit high colour variation across their range, but otherwise exhibit little morphological variation to distinguish them from close relatives. We examine the species status of one of the most abundant North American bumble bees, Bombus bifarius Cresson, which historically comprised two major taxa, bifarius s.s. and nearcticus. These lineages are recognized primarily by red and black variation in their mid-abdominal coloration; however, a continuum from black (nearcticus) to red (bifarius s.s.) variation has led to their historic synonymization. Integrating mitochondrial and nuclear data and whole-genome sequencing, we reveal a high level of both mitochondrial and nuclear divergence delimiting two morphologically cryptic species – the red bifarius s.s. and the colour-variable (black to red) nearcticus. Population genomic analysis supports an absence of recent genomic admixture and a strong population structure between the two clades, even in sympatry. Species distribution models predict partially differentiated niches between the genetically inferred clades with annual precipitation being a leading differentiating variable. The bifarius s.s. lineage also occupies significantly higher elevations, with regions of sympatry being among the highest elevations in nearcticus. Our data also support a subspecies-level divergence between the broadly distributed nearcticus and the island population vancouverensis. In this paper, we formally recognize the two species, Bombus bifarius Cresson and Bombus vancouverensis Cresson, the latter including the subspecies B. vancouverensis vancouverensis comb.n. and B. vancouverensis nearcticus comb.n ., with vancouverensis the name bearer due to year priority.     

Somatotrophs and lactotrophs: an immunohistochemical study of Gallus domesticus pituitary gland at different stages of induced moult

The objective of this study was to determine the distribution of somatotrophs and lactotrophs and conduct a morphometrical analysis of immunoreactive somatotrophs and lactotrophs in the pituitary glands of White Leghorn Hens (Gallus domesticus) during the period of induced moult. We divided the periods of induced moulting into three phases viz. 7, 14 and 21 days. The labeled alkalinephsphatase method with anti-GH (growth hormone) and anti-PRL (prolactin) as a primary antibody was used to detect somatotrophs and lactotrophs, in the midsagital sections of chicken adenohypophysis. Immunohistochemistry showed that somatotrophs are not only confined to the cephalo-caudal axis but can also be found in the caudal lobe; while lactotrophs were distributed in both lobes of the anterior pituitary gland at all stages of moulting (7, 14 and 21 days). Lactotrophs were of different shapes but somatotrophs were oval to round in morphology. At the given stages of induced moulting, some hypertrophied lactotrophs were also present after 7 days of induced moult in the anterior pituitary gland. However, there were moulting-related changes: from 7 to 21 days of induced moulting the immunoreactive-PRL cell population decreased, while the mean lactotroph size was more than that of somatotrophs. Basic quantitative and morphological information relating to somatotrophs and lactotrophs during the period of induced moult in laying hens is reported here and the changes brought about by induced moulting are restricted to PRL positive cells rather than GH positive cells.Key words: Moult, pituitary gland, somatotrophs, lactotrophs, chicken.     

Phenotypic variation in Streptomyces sp. DSM 40537, a lipoteichoic acid producing actinomycete

Aims:  To reinvestigate the production of lipoteichoic acid (LTA) by the actinomycete strain Streptomyces sp. DSM 40537 (=ATCC 3351).
Methods and Results:  LTA was extracted and purified from strain Streptomyces sp. DSM 40537. The identification of the LTA was confirmed by Western blotting with a monoclonal antibody. During these studies, two stable phenotypic variants of DSM 40537 were obtained, one of which released a distinctive orange pigment. 16S rRNA gene sequencing of each variant yielded identical sequences and allowed phylogenetic analysis to be performed.
Conclusions:  Streptomyces sp. DSM 40537 was shown to exhibit stable morphological variation. The strain was confirmed to be a LTA-producing actinomycete and to belong to the Streptomyces albidoflavus cluster within the genus Streptomyces .
Significance and Impact of the Study:  These data provide important support for the hypothesis that the distribution of LTA is linked to that of wall teichoic acids and emphasizes the need to reinvestigate LTA distribution in actinomycetes.