Exploration of the Production of Three Thiodiketopiperazines by an Endophytic Fungal Strain of Cophinforma mamane

Endophytic fungi possess a versatile metabolism which is related to their ability to live in diverse ecological niches. While culturing under laboratory conditions, their metabolism is mainly influenced by the culture media, time of incubation and other physicochemical factors. In this study, we focused on the production of 3 thiodiketopiperazines (TDKPs) botryosulfuranols A−C produced by an endophytic strain of Cophinforma mamane isolated from the leaves of Bixa orellana L collected in the Peruvian Amazon. We studied the time-course production of botryosulfuranols A−C during 28 days and evaluated the variations in the production of secondary metabolites, including the TDKPs, produced by C. mamane in response to different culture media, light versus dark conditions and different incubation times. We observed a short time-frame production of botryosulfuranol C while its production was significantly affected by the light conditions and nutrients of the culture media. Botryosulfuranols A and B showed a similar production pattern and a similar response to culturing conditions. Molecular networking allowed us to detect three compounds related to TDKPs that will be the focus of future experiments.     

Bistability in a Metabolic Network Underpins the De Novo Evolution of Colony Switching in Pseudomonas fluorescens

Phenotype switching is commonly observed in nature. This prevalence has allowed the elucidation of a number of underlying molecular mechanisms. However, little is known about how phenotypic switches arise and function in their early evolutionary stages. The first opportunity to provide empirical insight was delivered by an experiment in which populations of the bacterium Pseudomonas fluorescens SBW25 evolved, de novo, the ability to switch between two colony phenotypes. Here we unravel the molecular mechanism behind colony switching, revealing how a single nucleotide change in a gene enmeshed in central metabolism (carB) generates such a striking phenotype. We show that colony switching is underpinned by ON/OFF expression of capsules consisting of a colanic acid-like polymer. We use molecular genetics, biochemical analyses, and experimental evolution to establish that capsule switching results from perturbation of the pyrimidine biosynthetic pathway. Of central importance is a bifurcation point at which uracil triphosphate is partitioned towards either nucleotide metabolism or polymer production. This bifurcation marks a cell-fate decision point whereby cells with relatively high pyrimidine levels favour nucleotide metabolism (capsule OFF), while cells with lower pyrimidine levels divert resources towards polymer biosynthesis (capsule ON). This decision point is present and functional in the wild-type strain. Finally, we present a simple mathematical model demonstrating that the molecular components of the decision point are capable of producing switching. Despite its simple mutational cause, the connection between genotype and phenotype is complex and multidimensional, offering a rare glimpse of how noise in regulatory networks can provide opportunity for evolution.     

EnvPack an LCA-based tool for environmental assessment of packaging chains. Part 1: scope,methods and inventory of tool

The International Journal of Life Cycle Assessment - The environmental impact, resource use and waste generation of packaging has been a topic of worldwide debate. This resulted in founding the...     

Allelic exclusion of the immunoglobulin heavy chain locus is independent of its nuclear localization in mature B cells

In developing B cells, the immunoglobulin heavy chain (IgH) locus is thought to move from repressive to permissive chromatin compartments to facilitate its scheduled rearrangement. In mature B cells, maintenance of allelic exclusion has been proposed to involve recruitment of the non-productive IgH allele to pericentromeric heterochromatin. Here, we used an allele-specific chromosome conformation capture combined with sequencing (4C-seq) approach to unambigously follow the individual IgH alleles in mature B lymphocytes. Despite their physical and functional difference, productive and non-productive IgH alleles in B cells and unrearranged IgH alleles in T cells share many chromosomal contacts and largely reside in active chromatin. In brain, however, the locus resides in a different repressive environment. We conclude that IgH adopts a lymphoid-specific nuclear location that is, however, unrelated to maintenance of allelic exclusion. We additionally find that in mature B cells—but not in T cells—the distal V_H regions of both IgH alleles position themselves away from active chromatin. This, we speculate, may help to restrict enhancer activity to the productively rearranged V_H promoter element.     

Species-specific effects of thermal stress on the expression of genetic variation across a diverse group of plant and animal taxa under experimental conditions

Assessing the genetic adaptive potential of populations and species is essential for better understanding evolutionary processes. However, the expression of genetic variation may depend on environmental conditions, which may speed up or slow down evolutionary responses. Thus, the same selection pressure may lead to different responses. Against this background, we here investigate the effects of thermal stress on genetic variation, mainly under controlled laboratory conditions. We estimated additive genetic variance (V_A), narrow-sense heritability (h²) and the coefficient of genetic variation (CV_A) under both benign control and stressful thermal conditions. We included six species spanning a diverse range of plant and animal taxa, and a total of 25 morphological and life-history traits. Our results show that (1) thermal stress reduced fitness components, (2) the majority of traits showed significant genetic variation and that (3) thermal stress affected the expression of genetic variation (V_A, h² or CV_A) in only one-third of the cases (25 of 75 analyses, mostly in one clonal species). Moreover, the effects were highly species-specific, with genetic variation increasing in 11 and decreasing in 14 cases under stress. Our results hence indicate that thermal stress does not generally affect the expression of genetic variation under laboratory conditions but, nevertheless, increases or decreases genetic variation in specific cases. Consequently, predicting the rate of genetic adaptation might not be generally complicated by environmental variation, but requires a careful case-by-case consideration.Subject terms: Evolutionary genetics, Climate-change ecology, Biodiversity     

On the maintenance and origin of alternative strategies in the Ruff Philomachus pugnax

This paper has tried to answer the question of how the independent and the satellite strategy of the Ruff originated and has been maintained during evolution. It is not intended as a report of a piece of completed research but gives a number of tentative, but testable hypotheses. Data are presented that independent males and satellites are equally successful in copulating, provided that almost all copulations occur on leks, and independent males and satellites spend an equal proportion of their time on leks. The extent that males with the different strategies are attached to leks is analysed. Within the group of independent males, considerable differences exist: a resident male is strongly attached to only one particular lek and a marginal male seems to sample many leks. A satellite male behaves intermediately: he is attached to a limited number of leks. The mechanism for the maintenance of both strategies could not be explained by competition for resources (copulations). Contests between independent males and satellites are asymmetric, the satellite being the weaker contestant. The mechanism seems to be due to enlarging the accessibility of the resource by cooperation between both strategies. The ideas on the origin of the system are based mainly on the behaviour of females. There is no relation between the distribution of leks and the size of a female's foraging area, except that most leks are situated along the migration route. It further seems that the number of copulating females in the Netherlands is larger than the number of males on leks, but the number of breeding females is much lower. It is suggested that many females copulate on migration, which is related to extreme breeding conditions in the north of the range. Apart from a change in the sex ratio from south to north, a change in the proportion of satellites is also predicted. The origin of the system is ascribed to the incompatibility between favourable food conditions for chicks and further possibilities for inter-male competition on leks in the same area. The satellite strategy is considered as being derived from a non-competitive strategy accompanying females on migration. In the phase of cooperation between resident and satellite males, individual recognition became important. This could be the factor underlying the evolution of white plumages in satellites and the extreme plumage diversity in independent males.     

Autonomic neuropathy in Fabry disease: a prospective study using the Autonomic Symptom Profile and cardiovascular autonomic function tests

Background  

Fabry patients have symptoms and signs compatible with autonomic dysfunction. These symptoms and signs are considered to be due to impairment of the peripheral nervous system, but findings indicative of autonomic neuropathy in other diseases, such as orthostatic intolerance and male sexual dysfunction, are infrequently reported in Fabry disease. The aim of our study was to investigate autonomic symptoms and cardiovascular autonomic function in a large cohort of male and female Fabry patients.