Evolution of niche width and adaptive diversification

Theoretical models suggest that resource competition can lead to the adaptive splitting of consumer populations into diverging lineages, that is, to adaptive diversification. In general, diversification is likely if consumers use only a narrow range of resources and thus have a small niche width. Here we use analytical and numerical methods to study the consequences for diversification if the niche width itself evolves. We found that the evolutionary outcome depends on the inherent costs or benefits of widening the niche. If widening the niche did not have costs in terms of overall resource uptake, then the consumer evolved a niche that was wide enough for disruptive selection on the niche position to vanish; adaptive diversification was no longer observed. However, if widening the niche was costly, then the niche widths remained relatively narrow, allowing for adaptive diversification in niche position. Adaptive diversification and speciation resulting from competition for a broadly distributed resource is thus likely if the niche width is fixed and relatively narrow or free to evolve but subject to costs. These results refine the conditions for adaptive diversification due to competition and formulate them in a way that might be more amenable for experimental investigations.     

Resection guided by antibodies (REGAJ) a reappraisal after 10 years

Between 1986 and 1990 50 patients with ovarian cancer were submitted to a procedure which we called REGAJ-resection guided by antibodies. Using the radiolabelled murine monoclonal antibody OC 125, microscopic ovarian tumors producing CA 125 were detected during second-look surgery by a hand-held probe. Retrospective analysis after 10 years revealed that this procedure resulted in the cure of 4 of 11 patients, who would otherwise have been considered tumor free during second-look surgery and not further treated. Previous problems associated with the method can now be solved so that the clinical value of the procedure should be reconsidered.     

Variation of butyrate production in the gut microbiome in type 2 diabetes patients

Background

Diabetes mellitus type 2 is a common disease that poses a challenge to the healthcare system. The disease is very often diagnosed late. A better understanding of the relationship between the gut microbiome and type 2 diabetes can support early detection and form an approach for therapies. Microbiome analysis offers a potential opportunity to find markers for this disease. Next-generation sequencing methods can be used to identify the bacteria present in the stool sample and to generate a microbiome profile through an analysis pipeline. Statistical analysis, e.g., using Student’s t-test, allows the identification of significant differences. The investigations are not only focused on single bacteria, but on the determination of a comprehensive profile. Also, the consideration of the functional microbiome is included in the analyses. The dataset is not from a clinical survey, but very extensive.

Results

By examining 946 microbiome profiles of diabetes mellitus type 2 sufferers (272) and healthy control persons (674), a large number of significant genera (25) are revealed. It is possible to identify a large profile for type 2 diabetes disease. Furthermore, it is shown that the diversity of bacteria per taxonomic level in the group of persons with diabetes mellitus type 2 is significantly reduced compared to a healthy control group. In addition, six pathways are determined to be significant for type 2 diabetes describing the fermentation to butyrate. These parameters tend to have high potential for disease detection.

Conclusions

With this investigation of the gut microbiome of persons with diabetes type 2 disease, we present significant bacteria and pathways characteristic of this disease.

     

Bacteriophage-like particles associated with a spirochete.

A lysed Treponema bacterium containing cubic phage-like particles, approximately 40nm in diameter, has been observed by negative staining electron microscopy.     

Thermodynamics of double- and triple-helical aggregates formed by self-complementary oligoribonucleotides of the type rAxUy

The thermal denaturation of a series of oligoribonucleotides of the form rAxUy (x = 5 or 7 and y = 3-11) has been characterized by means of IR spectroscopy, UV spectroscopy, and DSC. IR spectra proved the occurrence of double- and triple-helical regions at various contents of uracil residues in the nucleotide. From DSC measurements transition enthalpies, entropies, and free enthalpies were derived. The effect of fraying in terminal base pairs of symmetrical nucleotides (x = y) was quantified. Thermodynamic excess parameters due to dangling ends (5'A and 3'U), terminal AU base pairs, and UAU base triplets were obtained by comparing DSC results from different nucleotides. Empirical values for contributions of base stacking and pairing to the stability of terminal AU base pairs have been estimated: for nucleotides under study with a high degree of fraying at the ends of the helix the major stabilization effect comes from base stacking. The size of the cooperative unit lambda in most nucleotides under study is larger than 1; i.e., in these cases intermolecular cooperation takes place. Through deconvolution of DSC data maximum populations of intermediate states FI,max were obtained. On the basis of these results all nucleotides under study were proved to melt in multistate manner. FI,max increases with the number of base pairs, decreases through dangling ends, and shows approximately constant values for triple-helical aggregates of the series rA5Uy as well as rA7Uy.     

贵州省青菜河水库坝下细肢新米虾（Neocaridina gracilipoda）的体长-体重关系研究

细肢新米虾（Neocaridina gracilipoda）是中国常见淡水虾类之一,在水域生态系统中起重要的作用（如在物质循环和能量流动中起链接作用）,但有关其基础生物学方面的研究目前却鲜见报道。有鉴于此,于2022年秋季在赤水河流域青菜河水库坝下（106°07′52″E,27°36′12″N）采集细肢新米虾490尾,通过对样本体长与体重的测定,掌握了此虾的体长和体重分布并报道了该物种的体长-体重关系。研究结果如下,青菜河水库坝下细肢新米虾：（1）体长介于10.60~32.13 mm（19.67 ± 2.54 mm）之间,优势体长集中在16.50~22.50 mm（n = 390,占总丰度的79.59%）;（2）体重介于0.01~0.44 g（0.11 ± 0.04 g）之间,优势体重集中在0.05~0.15 g（n = 415,占总丰度的84.69%）;（3）体长-体重的关系为W = 4 × 10^-5L^2.66 （R² = 0.78,n = 490）,b值（b = 2.66）与3存在显著性差异（P < 0.05）,即表明青菜河水库坝下细肢新米虾种群呈负异速生长。     

Interplay between alpha/beta and gamma interferons with B, T, and natural killer cells in the defense against herpes simplex virus type 1

The essential components of the immune system that control primary and chronic infection with herpes simplex virus type 1 (HSV-1) in mice were investigated. Infection within the first few days can be controlled by alpha/beta interferon (IFN-alpha/beta) alone without significant contribution of B, T, or NK cells. IFN-alpha/beta and IFN-gamma cooperate in the elimination of virus in the absence of these lymphocytes. In contrast, B, T, or NK cells appear to be required to control persistent infection with HSV-1. These results suggest that distinct and essential immune elements are recruited in a time-dependent fashion to control acute and persistent HSV-1 infection.