Ecosystem size predicts the probability of speciation in migratory freshwater fish

Predicting speciation is a fundamental goal of research in evolutionary ecology. The probability of speciation is often positively correlated with ecosystem size. Although the mechanisms driving this correlation are generally difficult to identify, a shared geographical and ecological context provides a suitable condition to study the mechanisms that promote speciation in large ecosystems by reducing the number of factors to be considered. Here, we determined the correlation between speciation and ecosystem size, and discuss the underlying mechanisms of this relationship, using a probable parallel ecotype formation for freshwater fish. Our population genetic analysis revealed that speciation of the landlocked goby, Rhinogobius sp. YB, of the Ryukyu Archipelago, Japan, from its migratory ancestor, R. brunneus, occurred in parallel across five islands. Logistic regression analysis showed that speciation probability could be predicted using island size. The results suggest that ecosystem size predicts the occurrence of adaptation and reproductive isolation, probably through its association with three possible factors: divergent selection strength, population persistence, and occurrence probability of habitat separation.     

ACTN1 Mutations Cause Congenital Macrothrombocytopenia

Congenital macrothrombocytopenia (CMTP) is a heterogeneous group of rare platelet disorders characterized by a congenital reduction of platelet counts and abnormally large platelets, for which CMTP-causing mutations are only found in approximately half the cases. We herein performed whole-exome sequencing and targeted Sanger sequencing to identify mutations that cause CMTP, in which a dominant mode of transmission had been suspected but for which no known responsible mutations have been documented. In 13 Japanese CMTP-affected pedigrees, we identified six (46%) affected by ACTN1 variants cosegregating with CMTP. In the entire cohort, ACNT1 variants accounted for 5.5% of the dominant forms of CMTP cases and represented the fourth most common cause in Japanese individuals. Individuals with ACTN1 variants presented with moderate macrothrombocytopenia with anisocytosis but were either asymptomatic or had only a modest bleeding tendency. ACTN1 encodes α-actinin-1, a member of the actin-crosslinking protein superfamily that participates in the organization of the cytoskeleton. In vitro transfection experiments in Chinese hamster ovary cells demonstrated that altered α-actinin-1 disrupted the normal actin-based cytoskeletal structure. Moreover, transduction of mouse fetal liver-derived megakaryocytes with disease-associated ACTN1 variants caused a disorganized actin-based cytoskeleton in megakaryocytes, resulting in the production of abnormally large proplatelet tips, which were reduced in number. Our findings provide an insight into the pathogenesis of CMTP.     

Formation of TEMPOL-hydroxylamine during reaction between TEMPOL and hydroxyl radical: HPLC/ECD study

Nitroxyl radicals are important antioxidants that have been used to protect animal tissues from oxidative damage. Their reaction with hydroxyl radical (^?OH) is generally accepted to be the mechanism of antioxidant function. However, the direct interaction of nitroxyl radicals with ^?OH does not always provide a satisfactory explanation in various pH, because the concentration of hydrogen ion may affect the generation of secondary ^?OH-derived radicals. In the present study, it was confirmed that the reaction between 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) and ^?OH generated TEMPOL-hydroxylamine, 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPON) and TEMPON-hydroxylamine using HPLC coupled with electrochemical detection. In the absence of NADH, TEMPOL-H may be generated by the reaction with secondary ^?OH-derived radicals in acidic condition. In the presence of NADH, a large proportion of the non-paramagnetic products was TEMPOL-H. Finally, it was clarified that TEMPOL-H was generated during dopamine metabolism, which is believed to be one of the ^?OH sources in pathological processes such as Parkinson's disease.     

Notes on the boletes of Japan 1. Four new species of the genus Boletus from central Honshu,Japan

Four new species of Boletus are fully described and illustrated from central Honshu, Japan: (1) B. panniformis (Section Calopodes) produces a typically felted and scabrous pileus, bitter flesh, a finely reticulate, red stipe, and occurs in subalpine, coniferous forests; (2) B. ventricosus (Section Appendiculati) forms a usually ventricose or subbulbous stipe, yellow to greyish orange, extremely short tubes, often pluriseptate, broadly clavate to doliform caulocystidia, and occurs in lowland, mixed forests; (3) B. cepaeodoratus (Section Appendiculati) possesses a pinkish red pileus, a usually finely reticulate stipe, relatively short tubes, and occurs in lowland, mixed forest; (4) B. viscidipellis (Section Luridi) yields a hairy, viscid pileus, intensely cyanescent flesh, and occurs in lowland, mixed forests.     

Functional consequences of mutational analysis of norovirus protease

Norovirus protease has been subjected to an extensive mutagenesis study. Ala-scanning mutation at 13 different positions (Trp6, Trp19, Thr27, Leu86, Leu95, Leu97, Met101, Gln117, Leu121, Thr134, Tyr143, Val144, and Val167) led to loss of function and/or stability. Considering the crystal structure of the protease, it was revealed that a hydroxyl group of Thr134 and an aromatic ring of Tyr143 were important for substrate recognition along with His157. It was notable that several of the residues identified were in close proximity to each other, suggesting their importance for the integrity and stability of the protease.