Trends in bacterial trehalose metabolism and significant nodes of metabolic pathway in the direction of trehalose accumulation

The current knowledge of trehalose biosynthesis under stress conditions is incomplete and needs further research. Since trehalose finds industrial and pharmaceutical applications, enhanced accumulation of trehalose in bacteria seems advantageous for commercial production. Moreover, physiological role of trehalose is a key to generate stress resistant bacteria by metabolic engineering. Although trehalose biosynthesis requires few metabolites and enzyme reactions, it appears to have a more complex metabolic regulation. Trehalose biosynthesis in bacteria is known through three pathways – OtsAB, TreYZ and TreS. The interconnections of in vivo synthesis of trehalose, glycogen or maltose were most interesting to investigate in recent years. Further, enzymes at different nodes (glucose‐6‐P, glucose‐1‐P and NDP‐glucose) of metabolic pathways influence enhancement of trehalose accumulation. Most of the study of trehalose biosynthesis was explored in medically significant Mycobacterium, research model Escherichia coli, industrially applicable Corynebacterium and food and probiotic interest Propionibacterium freudenreichii. Therefore, the present review dealt with the trehalose metabolism in these bacteria. In addition, an effort was made to recognize how enzymes at different nodes of metabolic pathway can influence trehalose accumulation.     

Nutritional Status of Adult Patients with Pulmonary Tuberculosis in Rural Central India and Its Association with Mortality

Under-nutrition is a known risk factor for TB and can adversely affect treatment outcomes. However, data from India are sparse, despite the high burden of TB as well as malnutrition in India. We assessed the nutritional status at the time of diagnosis and completion of therapy, and its association with deaths during TB treatment, in a consecutive cohort of 1695 adult patients with pulmonary tuberculosis in rural India during 2004 - 2009.Multivariable logistic regression was used to obtain adjusted estimates of the association of nutritional status with deaths during treatment. At the time of diagnosis, median BMI and body weights were 16.0 kg/m²and 42.1 kg in men, and 15.0 kg/m²and 34.1 kg in women, indicating that 80% of women and 67% of men had moderate to severe under-nutrition (BMI<17.0 kg/m²). Fifty two percent of the patients (57% of men and 48% of women) had stunting indicating chronic under-nutrition. Half of women and one third of men remained moderately to severely underweight at the end of treatment. 60 deaths occurred in 1179 patients (5%) in whom treatment was initiated. Severe under-nutrition at diagnosis was associated with a 2 fold higher risk of death. Overall, a majority of patients had evidence of chronic severe under-nutrition at diagnosis, which persisted even after successful treatment in a significant proportion of them. These findings suggest the need for nutritional support during treatment of pulmonary TB in this rural population.     

Circulating miRNA as novel markers for diastolic dysfunction

MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression. Though their significance is unclear, pioneer profiling studies have attributed specific serum miRNA signatures to different disease conditions. The diagnostic potential of miRNA detection in human plasma for cardiovascular disorders is beginning to be recognized as important. In this study, we examined miRNA profiling in isolated diastolic dysfunction (DD) with preserved systolic function to identify promising candidate miRNAs. The presence of these miRNAs was tested in stable patients with isolated DD, patients with stable compensated dilated cardiomyopathy (DCM—systolic plus diastolic dysfunction) and those with decompensated congestive heart failure secondary to dilated cardiomyopathy (DCM–CHF—systolic plus diastolic dysfunction). We identified new circulating miRNAs (miR-454, miR-500, miR-1246, miR-142-3p) which showed distinct patterns of expression in patients with diastolic dysfunction. The presence or absence of systolic dysfunction does not seem to affect this trend. MiR-454 and miR-500 are downregulated in diastolic dysfunction. MiR-1246 is upregulated in diastolic dysfunction. MiR-142-3p is downregulated in DCM and DCM–CHF groups but not in the DD group. The expression of miR-124-5p is highly upregulated in DCM but not in DD and DCM–CHF groups. We therefore propose that these circulating miRNAs may serve as novel biomarkers for diastolic dysfunction because in all of these patients the only common factor was diastolic dysfunction.     

Infection induced defence responses in sorghum,with special emphasis on accumulation of reactive oxygen species and cell wall modifications

Hemibiotrophic plant pathogens pass both biotrophic and necrotrophic phases during their infection cycle. Colletotrichum spp. exhibits two types of hemibiotrophy, i.e. intracellular and subcuticular intramural. Colletotrichum sublineolum infecting sorghum exhibits a typical intracellular type of hemibiotrophy. During the biotrophic stage of C. sublineolum infection in sorghum, several cell wall-associated defence reactions are activated and efficiently participate in stopping pathogen development. Among these defence reactions, generation and accumulation of reactive oxygen species (ROS) and cell wall barrier formation are key factors in resistance. This review focuses on the infection processes of C. sublineolum in sorghum and the defence responses activated, with special emphasis on accumulation of ROS and hydroxy-rich glyco-proteins (HRGPs).     

Demographic characteristics of the copepod <Emphasis Type="Italic">Acanthocyclops americanus</Emphasis> (Sars, 1863) (Copepoda: Cyclopoida) fed mixed algal (<Emphasis Type="Italic">Scenedesmus acutus</Emphasis>)-rotifer (<Emphasis Type="Italic">Brachionus havanaensis</Emphasis>) diet

The predatory copepod Acanthocyclops americanus is commonly found in shallow ponds and lakes in Mexico. We tested the survivorship and reproduction-related variables of this copepod, isolated from Lake Huetzalin (Xochimilco, Mexico City), on four mixed diets comprising two algal concentrations (0.8 × 10⁶ and 1.6 × 10⁶ cells ml⁻¹ of Scenedesmus acutus) and two rotifer densities (1 and 8 ind. ml⁻¹ of Brachionus havanaensis). Survivorship patterns of naupliar and adult stages of A. americanus were evaluated at 24 ± 1°C. The demography experiments were initiated with five females and five males (1:1 ratio, 5th copepodites) into each of the 16 test [= 4 diet combinations × 4 replicates (cohorts)] jars containing 50 ml medium and with one of the chosen algal-rotifer diets. Data on the survival of naupliar and copepodites (up to V) showed a high death rate (80%) in A. americanus by the time nauplii reached the adult stage. The duration of developmental time for nauplii and the copepodite V (C-V) was about 28 days by which time A. americanus became adults. Food combination had a significant effect on both survival and duration of the naupliar and C-V but not on the development time in C-I, C-II, C-III, and C-IV. Naupliar stages showed highest life expectancy at low food levels (rotifers or alga). Adult male and female copepods showed better survival under higher availability of rotifers in the medium, while higher algal density resulted in steep mortality during the first days. Average adult lifespan and life expectancy of A. americanus varied from 19 to 23 days, depending on the diet combination. Age-specific reproductive output (m _x ) of female A. americanus showed low reproduction (<10 offspring per female on any given day) when raised on low rotifer density, regardless of the algal concentration. On the other hand, enhanced offspring production (average of about 50 nauplii per female) was recorded when the rotifer density was higher (i.e., 8 ind. ml⁻¹). Gross and net reproductive rates varied from 48 to 438 and 27 to 318 offspring per female, respectively. In general, higher availability of rotifers in the medium resulted in higher (8–10 times as compared to those in low rotifer density) gross and net reproductive rates. There was no significant difference in the generation time (13–14 days) in relation to the diet combination. The rate of population increase (r) (range: 0.29–0.69 per day) increased with greater abundance of B. havanaensis in the medium. Thus, our study showed that inclusion of animal protein in the diet is necessary for high population growth rates of A. americanus.     

Strain-related differences in bacterivory and demography of Diaphanosoma mongolianum (Cladocera) in relation to diet and previous exposure to cyanobacteria in nature

We compared the demographic variables and bacterivory of two strains of Diaphanosoma mongolianum from two water bodies in Spain, one without Microcystis (Maidevera in Zaragoza) and the other with dense Microcystis (La Albufera of Valencia). We hypothesized that the strain rarely exposed to Microcystis would be unable to grow on this cyanobacterial diet. We fed both strains Monoraphidium caribeum and Microcystis aeruginosa, together and separately, and compared their demographic variables. Monoraphidium caribeum was cultured in the laboratory on a defined medium, while the cyanobacteria were collected from La Albufera and sonicated before feeding the cladocerans (at 0.5?×?10⁶ cells ml^?1). We also tested the growth of D. mongolianum on bacterial diets by using seston (0–15 µm), bacterioplankton (0–3 µm) and mixed fractions (3–15 µm), from sieving Lake Albufera. We conducted population growth and life table demography experiments at 25 °C, using the two strains of D. mongolianum. Both strains had r (population growth rate) ranging from 0.05 to 0.3 d^?1, on all diets. The r was higher (0.18 d^?1) on the 0–15 µm seston compared to the mixed fraction (0.12 d^?1) although D. mongolianum also grew well on bacterioplankton (0.16 d^?1) alone. The response of the strains collected from two different water bodies was different to the test diets. We found that both strains of D. mongolianum could effectively utilize Microcystis for survival and growth, regardless of previous exposure to the cyanobacteria. The tested cladocerans could also grow well on small sized food particles (0–3 µm and 0–15 µm). Our results explain why D. mongolianum is common in eutrophic water bodies