Planarian MBD2/3 is required for adult stem cell pluripotency independently of DNA methylation

Planarian adult stem cells (pASCs) or neoblasts represent an ideal system to study the evolution of stem cells and pluripotency as they underpin an unrivaled capacity for regeneration. We wish to understand the control of differentiation and pluripotency in pASCs and to understand how conserved, convergent or divergent these mechanisms are across the Bilateria. Here we show the planarian methyl-CpG Binding Domain 2/3 (mbd2/3) gene is required for pASC differentiation during regeneration and tissue homeostasis. The genome does not have detectable levels of 5-methylcytosine (5^mC) and we find no role for a potential DNA methylase. We conclude that MBD proteins may have had an ancient role in broadly controlling animal stem cell pluripotency, but that DNA methylation is not involved in planarian stem cell differentiation.     

Reaching Mothers and Babies with Early Postnatal Home Visits: The Implementation Realities of Achieving High Coverage in Large-Scale Programs

Background

Nearly half of births in low-income countries occur without a skilled attendant, and even fewer mothers and babies have postnatal contact with providers who can deliver preventive or curative services that save lives. Community-based maternal and newborn care programs with postnatal home visits have been tested in Bangladesh, Malawi, and Nepal. This paper examines coverage and content of home visits in pilot areas and factors associated with receipt of postnatal visits.

Methods

Using data from cross-sectional surveys of women with live births (Bangladesh 398, Malawi: 900, Nepal: 615), generalized linear models were used to assess the strength of association between three factors - receipt of home visits during pregnancy, birth place, birth notification - and receipt of home visits within three days after birth. Meta-analytic techniques were used to generate pooled relative risks for each factor adjusting for other independent variables, maternal age, and education.

Findings

The proportion of mothers and newborns receiving home visits within three days after birth was 57% in Bangladesh, 11% in Malawi, and 50% in Nepal. Mothers and newborns were more likely to receive a postnatal home visit within three days if the mother received at least one home visit during pregnancy (OR2.18, CI1.46–3.25), the birth occurred outside a facility (OR1.48, CI1.28–1.73), and the mother reported a CHW was notified of the birth (OR2.66, CI1.40–5.08). Checking the cord was the most frequently reported action; most mothers reported at least one action for newborns.

Conclusions

Reaching mothers and babies with home visits during pregnancy and within three days after birth is achievable using existing community health systems if workers are available; linked to communities; and receive training, supplies, and supervision. In all settings, programs must evaluate what community delivery systems can handle and how to best utilize them to improve postnatal care access.     

Trajectories of Self-Rated Health in People with Diabetes: Associations with Functioning in a Prospective Community Sample

Background

Self-rated health (SRH) is a single-item measure that is one of the most widely used measures of general health in population health research. Relatively little is known about changes and the trajectories of SRH in people with chronic medical conditions. The aims of the present study were to identify and describe longitudinal trajectories of self-rated health (SRH) status in people with diabetes.

Methods

A prospective community study was carried out between 2008 and 2011. SRH was assessed at baseline and yearly at follow-ups (n=1288). Analysis was carried out through trajectory modeling. The trajectory groups were subsequently compared at 4 years follow-up with respect to functioning.

Results

Four distinct trajectories of SRH were identified: 1) 72.2% of the participants were assigned to a persistently good SRH trajectory; 2) 10.1% were assigned to a persistently poor SRH trajectory; 3) mean SRH scores changed from good to poor for one group (7.3%); while 4) mean SRH scores changed from poor to medium/good for another group (10.4%). Those with a persistently poor perception of health status were at higher risk for poor functioning at 4 years follow-up than those whose SRH scores decreased from good to poor.

Conclusions

SRH is an important predictor for poor functioning in diabetes, but the trajectory of SRH seems to be even more important. Health professionals should pay attention to not only SRH per se, but also changes in SRH over time.     

Identification and characterization of <Emphasis Type="Italic">gerPI</Emphasis> and <Emphasis Type="Italic">gerPII</Emphasis> involved in epoxidation and hydroxylation of dihydrochalcolactone in <Emphasis Type="Italic">Streptomyces</Emphasis> species KCTC 0041BP

The macrolide antibiotics are biosynthesized by initial assembly of a macrolactone ring, followed by a series of post-polyketide (PKS) modifications. In general, the additional hydroxyl or epoxy groups are installed by cytochrome P450 enzymes, improving the bioactivity profile through structural diversification of natural products. The biosynthetic gene cluster for the 16-membered macrolide antibiotic dihydrochalcomycin (DHC) has been cloned from Streptomyces sp. KCTC 0041BP. Three cytochrome P450 genes are found in the DHC biosynthetic gene (ger) cluster. Two P450 enzymes were characterized from this cluster. Disruption of gerPI accumulated predominantly 12,13-de-epoxydihydrochalcomycin while disruption of gerPII accumulated 8-dehydroxy-12,13-de-epoxydihydrochalcomycin; DHC production was abolished in both cases. The results suggest that GerPII P450 catalyzes hydroxylation at the C₈ position followed by an epoxidation reaction catalyzed by GerPI P450 at the C₁₂–C₁₃ position.     

Direct Interspecies Electron Transfer between Geobacter metallireducens and Methanosarcina barkeri

Direct interspecies electron transfer (DIET) is potentially an effective form of syntrophy in methanogenic communities, but little is known about the diversity of methanogens capable of DIET. The ability of Methanosarcina barkeri to participate in DIET was evaluated in coculture with Geobacter metallireducens. Cocultures formed aggregates that shared electrons via DIET during the stoichiometric conversion of ethanol to methane. Cocultures could not be initiated with a pilin-deficient G. metallireducens strain, suggesting that long-range electron transfer along pili was important for DIET. Amendments of granular activated carbon permitted the pilin-deficient G. metallireducens isolates to share electrons with M. barkeri, demonstrating that this conductive material could substitute for pili in promoting DIET. When M. barkeri was grown in coculture with the H₂-producing Pelobacter carbinolicus, incapable of DIET, M. barkeri utilized H₂ as an electron donor but metabolized little of the acetate that P. carbinolicus produced. This suggested that H₂, but not electrons derived from DIET, inhibited acetate metabolism. P. carbinolicus-M. barkeri cocultures did not aggregate, demonstrating that, unlike DIET, close physical contact was not necessary for interspecies H₂ transfer. M. barkeri is the second methanogen found to accept electrons via DIET and the first methanogen known to be capable of using either H₂ or electrons derived from DIET for CO₂ reduction. Furthermore, M. barkeri is genetically tractable, making it a model organism for elucidating mechanisms by which methanogens make biological electrical connections with other cells.     

Site-specific recombination in Schizosaccharomyces pombe and systematic assembly of a 400kb transgene array in mammalian cells using the integrase of Streptomyces phage phiBT1

We have established the integrase of the Streptomyces phage phiBT1 as a tool for eukaryotic genome manipulation. We show that the phiBT1 integrase promotes efficient reciprocal and conservative site-specific recombination in vertebrate cells and in Schizosaccharomyces pombe, thus establishing the utility of this protein for genome manipulation in a wide range of eukaryotes. We show that the phiBT1 integrase can be used in conjunction with Cre recombinase to promote the iterative integration of transgenic DNA. We describe five cycles of iterative integration of a candidate mouse centromeric sequence 80 kb in length into a human mini-chromosome within a human-Chinese hamster hybrid cell line. These results establish the generality of the iterative site-specific integration technique.     

Advances in molecular cloning

“Molecular cloning” meaning creation of recombinant DNA molecules has impelled advancement throughout life sciences. DNA manipulation has become easy due to powerful tools showing exponential growth in applications and sophistication of recombinant DNA technology. Cloning genes has become simple what led to an explosion in the understanding of gene function by seamlessly stitching together multiple DNA fragments or by the use of swappable gene cassettes, maximizing swiftness and litheness. A novel archetype might materialize in the near future with synthetic biology techniques that will facilitate quicker assembly and iteration of DNA clones, accelerating the progress of gene therapy vectors, recombinant protein production processes and new vaccines by in vitro chemical synthesis of any in silico-specified DNA construct. The advent of innovative cloning techniques has opened the door to more refined applications such as identification and mapping of epigenetic modifications and high-throughput assembly of combinatorial libraries. In this review, we will examine the major breakthroughs in cloning techniques and their applications in various areas of biological research that have evolved mainly due to easy construction of novel expression systems.