Knowledge of the chromosome variation in wild populations is essential to understand the pathways and restrictions of karyotype
evolution in plants. The aim of this study is to conduct an intraspecific analysis of the karyotypes by fluorochrome banding
and ribosomal DNA (rDNA) loci detection by fluorescent in situ hybridization (FISH) and of the meiotic behaviour in natural
populations of Lathyrus nervosus, sect. Notolathyrus. Chromosome banding showed that, despite the high constancy in the karyotype formula and in the rDNA
loci among populations, there is intraspecific variation in the amount and distribution pattern of 4’,6-diamidino-2-phenylindole
(DAPI+) heterochromatin. However, those changes were not related to the total chromosome length of the haploid complements. This
fact demonstrates that structural chromosome changes may be one of the most important mechanisms for karyotype variation among
natural populations of L. nervosus. The chromosome number surveyed at the population level revealed the first case of polyploidy in South American species and
the first case of uneven polyploidy of the genus. All the chromosome markers analysed indicated that the polyploids found
originated by autopolyploidy. The meiotic analysis showed different chromosome abnormalities that may be generating numerical
and structural changes in the sporads. The finding of unreduced gametes that are alive at anthesis suggests sexual polyploidization
as the most probable mechanism involved in the origin of these 3x and 4x autopolyploid cytotypes in L. nervosus. 相似文献
The effects of monosaccharide constituents of lignocellulosic materials on exopolysaccharide (EPS) production by Mesorhizobium sp. Semia 816 were studied.
Results
According to the results, by using sugars commonly found in lignocellulosic biomass as carbon sources (glucose, arabinose and xylose), no significant differences were observed in the production of EPS, reaching 3.39 g/L, 3.33 g/L and 3.27 g/L, respectively. Differences were observed in monosaccharide composition, mainly in relation to rhamnose and glucuronic acid contents (1.8 times higher when arabinose was compared with xylose). However, the biopolymers showed no differences in relation to rheological properties, with EPS aqueous-based suspensions (1.0% w/v) presenting pseudoplastic behavior, and a slight difference in degradation temperatures. Using soybean hulls hydrolysate as carbon source, slightly higher values were obtained (3.93 g/L).
Conclusion
The results indicate the potential of the use of lignocellulosic hydrolysates containing these sugars as a source of carbon in the cultivation of Mesorhizobium sp. Semia 816 for the production of EPS with potential industrial applications.
In resource-poor settings, HIV positive mothers are recommended to choose between 'Exclusive breastfeeding' (EBF) or 'Exclusive replacement feeding' (ERF). Acceptability, Feasibility, Affordability, Sustainability and Safety (AFASS) has been the World Health Organization (WHO)'s a priori criteria for ERF the last ten years. 'AFASS' has become a mere acronym among many workers in the field of prevention of mother-to-child transmission of HIV, PMTCT. Thereby, non-breastfeeding has been suggested irrespective of social norms. EBF for the first half of infancy is associated with huge health benefits for children in areas where infant mortality is high. But, even if EBF has been recommended for a decade, few mothers are practicing it. We set out to understand fathers' and mothers' infant feeding perceptions and the degree to which EBF and ERF were 'AFASS.'
Methods
Eight focus groups with 81 informants provided information for inductive content analysis. Four groups were held by men among men and four groups by women among women in Mbale District, Eastern Uganda.
Results
Two study questions emerged: How are the different feeding options understood and accepted? And, what are men's and women's responsibilities related to infant feeding? A mother's commitment to breastfeed and the husband's commitment to provide for the family came out strongly. Not breastfeeding a newborn was seen as dangerous and as unacceptable, except in cases of maternal illness. Men argued that not breastfeeding could entail sanctions by kin or in court. But, in general, both men and women regarded EBF as 'not enough' or even 'harmful.' Among men, not giving supplements to breast milk was associated with poverty and men's failure as providers. Women emphasised lack of time, exhaustion, poverty and hunger as factors for limited breast milk production. Although women had attended antenatal teaching they expressed a need to know more. Most men felt left out from health education.
Conclusion
Breastfeeding was the expected way to feed the baby, but even with existing knowledge among mothers, EBF was generally perceived as impossible. ERF was overall negatively sanctioned. Greater culture-sensitivity in programs promoting safer infant feeding in general and in HIV-contexts in particular is urgently needed, and male involvement is imperative.
Trial Registration
The study was part of formative studies for the ongoing study PROMISE EBF registered at http://clinicaltrials.gov (NCT00397150). 相似文献
Chaos Game Representation (CGR) is an iterated function that bijectively maps discrete sequences into a continuous domain. As a result, discrete sequences can be object of statistical and topological analyses otherwise reserved to numerical systems. Characteristically, CGR coordinates of substrings sharing an L-long suffix will be located within 2-L distance of each other. In the two decades since its original proposal, CGR has been generalized beyond its original focus on genomic sequences and has been successfully applied to a wide range of problems in bioinformatics. This report explores the possibility that it can be further extended to approach algorithms that rely on discrete, graph-based representations.
Results
The exploratory analysis described here consisted of selecting foundational string problems and refactoring them using CGR-based algorithms. We found that CGR can take the role of suffix trees and emulate sophisticated string algorithms, efficiently solving exact and approximate string matching problems such as finding all palindromes and tandem repeats, and matching with mismatches. The common feature of these problems is that they use longest common extension (LCE) queries as subtasks of their procedures, which we show to have a constant time solution with CGR. Additionally, we show that CGR can be used as a rolling hash function within the Rabin-Karp algorithm.
Conclusions
The analysis of biological sequences relies on algorithmic foundations facing mounting challenges, both logistic (performance) and analytical (lack of unifying mathematical framework). CGR is found to provide the latter and to promise the former: graph-based data structures for sequence analysis operations are entailed by numerical-based data structures produced by CGR maps, providing a unifying analytical framework for a diversity of pattern matching problems. 相似文献
The EVIDENCE (EVidence of Interferon Dose-response: European North American Comparative Efficacy) study was an international,
randomized, open-label, assessor-blinded, parallel-group study assessing the efficacy and tolerability of interferon (IFN)
beta-1a, 44 mcg subcutaneously (sc) three times weekly (tiw), and IFN beta-1a, 30 mcg intramuscularly (im) once weekly (qw),
in patients with relapsing-remitting multiple sclerosis (RRMS). The aim of this analysis was to assess whether reductions
in T2 burden of disease (BOD) were greater for patients receiving IFN beta-1a, 44 mcg sc tiw, than for those treated with
IFN beta-1a, 30 mcg im qw, and to assess the impact of neutralizing antibodies (NAbs). 相似文献
We present a biological data warehouse called Atlas that locally stores and integrates biological sequences, molecular interactions,
homology information, functional annotations of genes, and biological ontologies. The goal of the system is to provide data,
as well as a software infrastructure for bioinformatics research and development. 相似文献
Lake Ichkeul in northern Tunisia is a Ramsar site, a MAB Biosphere Reserve and a UNESCO World Heritage Site. The system is one of the most important coastal wetlands in North Africa, especially as an over-wintering area for migratory birds, particularly Palaearctic waterfowl. The present study was aimed at diagnosing the status of fish species in Lake Ichkeul and documenting their annual and seasonal occurrence within the system. Fish samples were collected monthly at 22 sites from March 2011 to April 2012 using a variety of gears, including a dragnet, gillnet, trammelnet, frynet and beach-seine. Temperature and salinity measurements were taken at each site, while fishes were obtained from only 11 sites, representing mainly lacustrine stations. A total of 18 fish species belonging to 14 genera and 12 families were identified, with Mugilidae dominating with four species, followed by Syngnathidae with three species. This study represents a relative recovery in terms of fish species richness, since only 13 species were recorded here between 2003 and 2007. However, the numbers of fish caught, especially of the commercial taxa, seem to have declined in recent years, and the number of species currently present is much lower than that of several decades ago. Increasing human pressures, particularly reductions in catchment freshwater inputs, a breakdown in ecosystem connectivity, pollution and over-fishing appear to be the principal causes for the decline in fish abundance and diversity. 相似文献
We evaluated the activity of methanolic extracts of Melaleuca cajuputi flowers against the filarial worm Brugia pahangi and its bacterial endosymbiont Wolbachia. Anti-Wolbachia activity was measured in worms and in Aedes albopictus Aa23 cells by PCR, electron microscopy, and other biological assays. In particular, microfilarial release, worm motility, and viability were determined. M. cajuputi flower extracts were found to significantly reduce Wolbachia endosymbionts in Aa23 cells, Wolbachia surface protein, and microfilarial release, as well as the viability and motility of adult worms. Anti-Wolbachia activity was further confirmed by observation of degraded and phagocytized Wolbachia in worms treated with the flower extracts. The data provided in vitro and in vivo evidence that M. cajuputi flower extracts inhibit Wolbachia, an activity that may be exploited as an alternative strategy to treat human lymphatic filariasis. 相似文献
Propagation of long terminal repeat (LTR)-bearing retrotransposons and
retroviruses requires integrase (IN, EC 2.7.7.-), encoded by the
retroelements themselves, which mediates the insertion of cDNA copies back
into the genome. An active retrotransposon family, BARE-1, comprises
approximately 7% of the barley (Hordeum vulgare subsp. vulgare) genome. We
have generated models for the secondary and tertiary structure of BARE-1 IN
and demonstrate their similarity to structures for human immunodeficiency
virus 1 and avian sarcoma virus INs. The IN core domains were compared for
80 clones from 28 Hordeum accessions representative of the diversity of the
genus. Based on the structural model, variations in the predicted, aligned
translations from these clones would have minimal structural and functional
effects on the encoded enzymes. This indicates that Hordeum retrotransposon
IN has been under purifying selection to maintain a structure typical of
retroviral INs. These represent the first such analyses for plant INs.
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