Decreased anthocyanidin reductase expression strongly decreases silver birch (Betula pendula) growth and alters accumulation of phenolics

Phenolics, formed via a complex phenylpropanoid pathway, are important defensive agents in plants and are strongly affected by nitrogen (N) fertilization. Proanthocyanidins (PAs) are one possible endpoint of the phenylpropanoid pathway, and anthocyanidin reductase (ANR) represents a key enzyme in PA biosynthesis. In this study, the expression of silver birch (Betula pendula) anthocyanidin reductase BpANR was inhibited using the RNA interference (RNAi) method, in three consequent BpANR RNAi (ANRi birches) lines. The growth, the metabolites of the phenylpropanoid pathway, and the number of resin glands of the ANRi birches were studied when grown at two N levels. ANRi birches showed decreased growth and reduction in PA content, while the accumulation of total phenolics in both stems and leaves increased. Moreover, ANRi birches produced more resin glands than did wild‐type (WT) birches. The response of ANRi birches to N depletion varied compared with that of WT birches, and in particular, the concentrations of some phenolics in stems increased in WT birches and decreased in ANRi birches. Because the inhibition of PAs biosynthesis via ANR seriously affected birch growth and resulted in accumulation of the precursors, the native level of PAs in plant tissues is assumed to be the prerequisite for normal plant growth. This draws attention to the real plant developmental importance of PAs in plant tissues.     

Inhibition of pancreatic lipase by mixed micelles of diethyl p-nitrophenyl phosphate and bile salts

Solubility and Sephadex filtration assays have shown that dissolved diethyl p-nitrophenyl phosphate can be included into bile salt micelles with a partition coefficient of 32 : 1. This inclusion is probably a prerequisite for the organophosphate to inhibit lipase. The essential role played by colipase confirms that the primary step in the inhibition is an interaction of lipase with bile salt containing micelles. Therefore, it appears that the requirements of lipase towards specific substrates and inhibitors are very similar. The inhibition rate strongly depends on the total bile salt concentration and on the micellar concentration of the organophosphate. This effect may be explained, at least qualitatively, by a competition between simple and mixed micelles for the binding of colipase and lipase.     

Reliability analysis of microarray data using fuzzy c-means and normal mixture modeling based classification methods

MOTIVATION: A serious limitation in microarray analysis is the unreliability of the data generated from low signal intensities. Such data may produce erroneous gene expression ratios and cause unnecessary validation or post-analysis follow-up tasks. Therefore, the elimination of unreliable signal intensities will enhance reproducibility and reliability of gene expression ratios produced from microarray data. In this study, we applied fuzzy c-means (FCM) and normal mixture modeling (NMM) based classification methods to separate microarray data into reliable and unreliable signal intensity populations. RESULTS: We compared the results of FCM classification with those of classification based on NMM. Both approaches were validated against reference sets of biological data consisting of only true positives and true negatives. We observed that both methods performed equally well in terms of sensitivity and specificity. Although a comparison of the computation times indicated that the fuzzy approach is computationally more efficient, other considerations support the use of NMM for the reliability analysis of microarray data. AVAILABILITY: The classification approaches described in this paper and sample microarray data are available as Matlab( TM ) (The MathWorks Inc., Natick, MA) programs (mfiles) and text files, respectively, at http://rc.kfshrc.edu.sa/bssc/staff/MusaAsyali/Downloads.asp. The programs can be run/tested on many different computer platforms where Matlab is available. CONTACT: asyali@kfshrc.edu.sa.     

Arabidopsis genes involved in acyl lipid metabolism. A 2003 census of the candidates,a study of the distribution of expressed sequence tags in organs,and a web-based database

The genome of Arabidopsis has been searched for sequences of genes involved in acyl lipid metabolism. Over 600 encoded proteins have been identified, cataloged, and classified according to predicted function, subcellular location, and alternative splicing. At least one-third of these proteins were previously annotated as "unknown function" or with functions unrelated to acyl lipid metabolism; therefore, this study has improved the annotation of over 200 genes. In particular, annotation of the lipolytic enzyme group (at least 110 members total) has been improved by the critical examination of the biochemical literature and the sequences of the numerous proteins annotated as "lipases." In addition, expressed sequence tag (EST) data have been surveyed, and more than 3,700 ESTs associated with the genes were cataloged. Statistical analysis of the number of ESTs associated with specific cDNA libraries has allowed calculation of probabilities of differential expression between different organs. More than 130 genes have been identified with a statistical probability > 0.95 of preferential expression in seed, leaf, root, or flower. All the data are available as a Web-based database, the Arabidopsis Lipid Gene database (http://www.plantbiology.msu.edu/lipids/genesurvey/index.htm). The combination of the data of the Lipid Gene Catalog and the EST analysis can be used to gain insights into differential expression of gene family members and sets of pathway-specific genes, which in turn will guide studies to understand specific functions of individual genes.     

Prevalence of Exclusive Breastfeeding Practices and associated factors among mothers in Bahir Dar city,Northwest Ethiopia: a community based cross-sectional study

Background

Breastfeeding is an unequalled way of providing ideal food for the healthy growth and development of infants. World Health Organization (WHO) recommend exclusive breastfeeding (EBF) for six months which has a great contribution in reducing under five mortality, which otherwise leads to death of 88/1000 live birth yearly in Ethiopia. Hence, this study aimed to assess prevalence of EBF and associated factors in mothers in the city of Bahir Dar, Northwest Ethiopia.

Methods

A community-based cross-sectional study was conducted from 10 to 25 June 2012 among mothers who delivered 12 months earlier in Bahir Dar city, Northwest Ethiopia. A cluster sampling technique was used to select a sample of 819 participants. Data were collected using a structured and pre-tested questionnaire by face-to-face interview technique. Bivariate and multivariate analyses were performed to check associations and control confounding.

Results

Of 819 mother-infant pairs sampled, the overall age appropriate rate of EBF practice was found to be 50.3%. Having a young infant aged 0-1 month (AOR = 3.77, 95% CI = 1.54, 9.24) and 2-3 months (AOR = 2.80, 95% CI = 1.71, 4.58), being a housewife (AOR = 2.16, 95% CI = 1.48, 3.16), having prenatal EBF plan (AOR = 3.75, 95% CI = 2.21, 6.37), delivering at a health facility (AOR = 3.02, 95% CI = 1.55, 5.89), giving birth vaginally (AOR = 2.33, 95% CI = 1.40, 3.87) and receiving infant feeding counseling/advice (AOR = 5.20, 95% CI = 2.13, 12.68) were found to be significantly associated with EBF practice.

Conclusion

Prevalence of exclusive breastfeeding was low in Bahir Dar. Strengthening infant feeding advice/counseling both at the community and institutional levels, promoting institutional delivery, providing adequate pain relief and early assistance for mothers who gave birth by caesarean section, and enabling every mother a prenatal EBF plan during antenatal care were recommended in order to increase the proportion of women practicing EBF.

     

Macroinvertebrates as unreliable indicators of human disturbance in temporary depression wetlands of the south-western Cape, South Africa

Macroinvertebrates have a successful history of use as indicators of human impact in lotic environments. More recently, macroinvertebrate indices have been recommended for use in certain wetland types. Yet some authors do not recommend macroinvertebrates indices of wetland condition in areas with pronounced natural environmental heterogeneity. Our study provides a preliminary assessment of the feasibility of using macroinvertebrates for bioassessment of temporary isolated depression wetlands in the south-western Cape region of South Africa. We expected natural environmental heterogeneity among wetlands to exert a stronger influence on macroinvertebrates than human disturbance factors. Partitioning of the variation in macroinvertebrate assemblage composition that could be attributed to human disturbance factors (within and adjacent to wetlands), environmental variables and spatio-temporal factors indicated that environmental and spatio-temporal factors independent of human disturbances largely determined assemblage composition, whilst human disturbance played a relatively minor role. Linear regressions of taxon richness/diversity measures, individual families and a collation of metrics against measures of habitat transformation around wetlands and scores from a rapid assessment index of human disturbance revealed poor relationships. The univariate and multivariate patterns observed in this study do not lend themselves to the creation of a macroinvertebrate index of human disturbance for temporary wetlands in the region.     

Tsetse blood-meal sources,endosymbionts and trypanosome-associations in the Maasai Mara National Reserve,a wildlife-human-livestock interface

African trypanosomiasis (AT) is a neglected disease of both humans and animals caused by Trypanosoma parasites, which are transmitted by obligate hematophagous tsetse flies (Glossina spp.). Knowledge on tsetse fly vertebrate hosts and the influence of tsetse endosymbionts on trypanosome presence, especially in wildlife-human-livestock interfaces, is limited. We identified tsetse species, their blood-meal sources, and correlations between endosymbionts and trypanosome presence in tsetse flies from the trypanosome-endemic Maasai Mara National Reserve (MMNR) in Kenya. Among 1167 tsetse flies (1136 Glossina pallidipes, 31 Glossina swynnertoni) collected from 10 sampling sites, 28 (2.4%) were positive by PCR for trypanosome DNA, most (17/28) being of Trypanosoma vivax species. Blood-meal analyses based on high-resolution melting analysis of vertebrate cytochrome c oxidase 1 and cytochrome b gene PCR products (n = 354) identified humans as the most common vertebrate host (37%), followed by hippopotamus (29.1%), African buffalo (26.3%), elephant (3.39%), and giraffe (0.84%). Flies positive for trypanosome DNA had fed on hippopotamus and buffalo. Tsetse flies were more likely to be positive for trypanosomes if they had the Sodalis glossinidius endosymbiont (P = 0.0002). These findings point to complex interactions of tsetse flies with trypanosomes, endosymbionts, and diverse vertebrate hosts in wildlife ecosystems such as in the MMNR, which should be considered in control programs. These interactions may contribute to the maintenance of tsetse populations and/or persistent circulation of African trypanosomes. Although the African buffalo is a key reservoir of AT, the higher proportion of hippopotamus blood-meals in flies with trypanosome DNA indicates that other wildlife species may be important in AT transmission. No trypanosomes associated with human disease were identified, but the high proportion of human blood-meals identified are indicative of human African trypanosomiasis risk. Our results add to existing data suggesting that Sodalis endosymbionts are associated with increased trypanosome presence in tsetse flies.     

Evapotranspiration and water yield of a pine‐broadleaf forest are not altered by long‐term atmospheric [CO2] enrichment under native or enhanced soil fertility

Changes in evapotranspiration (ET) from terrestrial ecosystems affect their water yield (WY), with considerable ecological and economic consequences. Increases in surface runoff observed over the past century have been attributed to increasing atmospheric CO₂ concentrations resulting in reduced ET by terrestrial ecosystems. Here, we evaluate the water balance of a Pinus taeda (L.) forest with a broadleaf component that was exposed to atmospheric [CO₂] enrichment (ECO₂; +200 ppm) for over 17 years and fertilization for 6 years, monitored with hundreds of environmental and sap flux sensors on a half‐hourly basis. These measurements were synthesized using a one‐dimensional Richard's equation model to evaluate treatment differences in transpiration (T), evaporation (E), ET, and WY. We found that ECO₂ did not create significant differences in stand T, ET, or WY under either native or enhanced soil fertility, despite a 20% and 13% increase in leaf area index, respectively. While T, ET, and WY responded to fertilization, this response was weak (<3% of mean annual precipitation). Likewise, while E responded to ECO₂ in the first 7 years of the study, this effect was of negligible magnitude (<1% mean annual precipitation). Given the global range of conifers similar to P. taeda, our results imply that recent observations of increased global streamflow cannot be attributed to decreases in ET across all ecosystems, demonstrating a great need for model–data synthesis activities to incorporate our current understanding of terrestrial vegetation in global water cycle models.