Sexual selection in mushroom-forming basidiomycetes

We expect that sexual selection may play an important role in the evolution of mushroom-forming basidiomycete fungi. Although these fungi do not have separate sexes, they do play female and male roles: the acceptance and the donation of a nucleus, respectively. The primary mycelium (monokaryon) of basidiomycete fungi, growing from a germinating sexual spore, is hermaphroditic, but it loses female function upon the acceptance of a second nucleus. The resulting dikaryon with two different nuclei in each cell retains a male potential as both nuclei can fertilize receptive mycelia. We tested the occurrence of sexual selection in the model species of mushroom-forming basidiomycetes, Schizophyllum commune, by pairing monokaryons with fully compatible dikaryons. In most pairings, we found a strong bias for one of the two nuclei although both were compatible with the monokaryon when paired alone. This shows that sexual selection can occur in mushroom-forming basidiomycetes. Since the winning nucleus of a dikaryon occasionally varied depending on the receiving monokaryon, we infer that sexual selection can operate through choosiness of the receiving individual (analogous to female choice). However, in other cases the same nucleus won, irrespective of the receiving monokaryon, suggesting that competition between the two nuclei of the donating mycelium (analogous to male–male competition) might also play a role.     

BMI及LDL-C水平与冠脉慢血流的相关性研究

目的:探讨低密度脂蛋白胆固醇及身高体重指数与冠状动脉慢血流现象(Coronary slow flow phenomenon,CSFP)的相关性。方法:在我院2013年上半年因不典型胸痛行冠脉造影术患者中,选取冠脉官腔无明显狭窄(40%)且至少一支冠脉根据校正的TIMI血流分级方法被评为慢血流的患者进入慢血流组(CSFP组)79例,选取同期无明显狭窄且血流速度正常的患者71例为对照组,对两组入院各项常规检查检验指标进行分析,筛选导致冠脉慢血流的危险因素。结果:在两组比较中,CSFP组的慢血流组吸烟率、身体质量指数(Body Mass Index,BMI)、甘油三酯(Triglyceride,TG)、低密度脂蛋白胆固醇(Low density lipoprotein cholesterol,LDL-C)、尿酸(Uric acid,UA)水平明显高于对照组;亚组分析中显示BMI、LDL-C水平随受累血管数量增多呈上升趋势,且具有统计学意义;经回归分析,显示BMI、LDL-C水平的升高对冠脉慢血流的发生有显著影响,且与冠脉血流速度(帧数)呈正相关。结论:BMI、LDL-C水平与冠脉慢血流的发病的密切相关。     

The Distribution Patterns of Bases of Protein-coding Genes,Non-coding ORFs,and Intergenic Sequences in Pseudomonas aeruginosa PA01 Genome and its Implications

Abstract

The distribution patterns of bases of DNA fragments in different regions in P. aeruginosa genome are analyzed in this paper. It's shown that 5565 protein-coding genes, 17315 non- coding ORFs, and 1104 intergenic sequences are located into seven clusters based on their base frequencies. Almost all the protein-coding genes are contained in one of the seven clusters. The significant difference of base frequencies among three codon positions in high GC genome, which arouse the division between the distribution patterns of bases of six reading frames of protein-coding genes, is responsible for the appearance of the clustering phenomenon. In the light of the clustering phenomenon, the author supposes that the anitisense strand ORFs, particularly those corresponding to Frame 2′ and Frame 3′, may not code for proteins in P. aeruginosa genome.     

促生小菇属菌株M23对黑果腺肋花楸光合作用的影响

以黑果腺肋花楸为试验材料,设置5个处理组,分别为阴性对照(CK)、阳性对照(PCK)、大田条件下根施低剂量T1(每株50 g)、中剂量T2(每株100 g)和高剂量T3(每株200 g)3个水平的小菇属菌株M23,分析各处理组黑果腺肋花楸的农艺性状、叶绿素含量和生理指标,并利用L-6400便携式光合仪测定光合特性日变化...     

Long distance dispersal and the fate of a gene from the colonization front

There is an increasing recognition that long distance dispersal (LDD) plays a key role in establishing spatial genetic structure during colonization. Recent works, focused on short distance dispersal, demonstrated that a neutral mutation arising at the colonization front can either ‘surf’ with the wave front and reach high frequencies or stay near its place of origin at low frequencies. Here, we examine how LDD, and more generally the shape of the dispersal kernel, modifies this phenomenon and how the width of the colonization corridor affects the fate of the mutation. We demonstrate that when LDD events are more frequent, the ‘surfing phenomenon’ is less frequent, probably because any alleles can get far ahead from the colonization front and preclude the invasion by others alleles, thus leading to an attenuation of the diversity loss. We also demonstrate that the width of the colonization corridor influences the fate of the mutation, wide spaces decreasing the probability of invasion. Overall, the genetic structure of diversity resulted not only from LDD but also particularly from the shape of the dispersal kernel.     

Historical and conceptual background of self-organization by reactive processes

Order, form, pattern and organization are properties central to much living matter. The physicochemical processes by which an initially homogeneous solution of reacting chemicals or biochemicals might self-organize is hence a question of fundamental biological importance. In most cases, solutions of reacting chemicals in a test-tube do not self-organize. Because of this, for many years, it was not thought possible that reactive processes could result in self-organization. However, progressively over the last hundred years, it has been shown that this is not always the case, and under certain conditions, the combination of reaction with molecular diffusion can lead to macroscopic self-organization. In 'complex' systems comprised of populations of strongly coupled elements, new 'emergent' properties, such as self-organization, arise by way of the dynamics of the system. Self-organizing reaction-diffusion systems form a specific type of complex system. Here, I will give a personal overview of the conceptual and historical background to this approach with an emphasis on biological self-organization.     

16例婴幼儿卡梅现象临床疗效分析

目的:总结16例卡梅现象患儿的临床治疗过程,为该病提供诊疗方案.方法:收集我科在2016年5月至2020年1月期间收治并确诊为卡梅现象的16例患儿(男13例、女3例)的临床资料并进行回顾性分析.结果:患儿在住院和门诊期间接受药物(糖皮质激素、长春新碱、西罗莫司)、介入栓塞、微波消融术和瘤内硬化剂注射等治疗.5例(31....     

Overwinter mass loss of snowshoe hares in the Yukon: starvation, stress, adaptation or artefact?

1. Overwinter mass loss can reduce energetic requirements in mammals (Dehnel's phenomenon). Alternatively, mass loss can result from food limitation or high predation risk. 2. We use data from fertilizer, food-supplementation and predator-exclusion experiments in the Yukon during a population cycle from 1986 to 1996 to test the causes of overwinter mass loss by snowshoe hares (Lepus americanus). In all years, some hares on control sites gained mass overwinter. During the increase phase the majority gained mass, but in all other phases the majority lost mass. 3. Snowshoe hares weighing <1000 g in autumn always gained mass overwinter, as did the majority that weighed 1000-1400 g. Hares weighing >1800 g in autumn usually lost mass. 4. Snowshoe hares on the predator-exclosure + food site gained mass overwinter in all years. Hares on the food-supplementation sites lost mass during the decline but gained mass in all other phases. Fertilization had little effect on mass dynamics. 5. Snowshoe hares were more likely to lose mass during winters with low survival rates. Snowshoe hares on the predator-exclosure treatments were more likely to gain mass than were hares on control sites. 6. Overwinter mass loss was correlated with maximum snow depth. At equivalent snow depths, hares on food-supplemented areas lost 98 g (+/- 14.6 SE) less on average than hares on the controls and predator-exclosure treatment. 7. Bone-marrow fat was related to body mass and cause of death. Small hares had the lowest marrow fat. Hares killed by humans had higher marrow fat than those killed by predators; hares that simply died had the lowest marrow fat. Hares on food-supplemented sites had the highest kidney and marrow fat. 8. Overwinter-mass loss for snowshoe hares is explained interactively by winter conditions, food supply, predation risk and autumn mass. Some snowshoe hares lost mass overwinter in all years and on all treatments, suggesting that reducing body mass may facilitate survival, especially in cases where foraging costs are high energetically or increase predation risk.     

Oral L-arginine can reverse digital necrosis in Raynaud's phenomenon

Raynaud's phenomenon is characterized by transient reduction in blood supply through the small arteries in the hands and feet. Severe Raynaud's phenomenon can cause digital necrosis. It has been hypothesized that nitric oxide may have a role in Raynaud's phenomenon. We report two cases in which oral L-arginine reversed digital necrosis in Raynaud's phenomenon and two additional cases in which the symptoms of severe Raynaud's phenomenon were improved with oral L-arginine. These reports suggest that a defect in nitric oxide synthesis or metabolism is present in Raynaud's phenomenon. They also suggest a potential role for oral L-arginine therapy in Raynaud's phenomenon, especially in Raynaud's phenomenon with digital necrosis.