A new hypothesis for species coexistence: male–male repulsion promotes coexistence of competing species

We propose a new hypothesis for species coexistence by considering behavioral interactions between individuals. The hypothesis states that repulsive behavior between conspecific males (male–male repulsion) creates space for competing species, which promotes their coexistence. This hypothesis can explain the coexistence of two competing species even when their ecological niches completely overlap in spatially homogeneous environments. In addition, the mechanisms underlying such behavior might play a role in enabling the coexistence of two species immediately after speciation, with little or no niche differentiation, as in the case of cichlid fish communities, for example. Although there is limited evidence supporting this hypothesis, it can nevertheless explain the occurrence of species coexistence and biodiversity, which cannot be explained by previous theories.     

The Influence of 5-HTTLPR Genotype on the Association between the Plasma Concentration and Therapeutic Effect of Paroxetine in Patients with Major Depressive Disorder

Introduction

The efficacy of treatment with selective serotonin reuptake inhibitors in patients with major depressive disorder (MDD) can differ depending on the patient''s serotonin transporter-linked polymorphic region (5-HTTLPR) genotype, and the effects of varying plasma concentrations of drugs can also vary. We investigated the association between the paroxetine plasma concentration and clinical response in patients with different 5-HTTLPR genotypes.

Methods

Fifty-one patients were enrolled in this study. The Montgomery-Asberg Depression Rating Scale (MADRS) was used to evaluate patients at 0, 1, 2, 4, and 6 weeks. The patients'' paroxetine plasma concentrations at week 6 were measured using high-performance liquid chromatography. Additionally, their 5-HTTLPR polymorphisms (alleles S and L) were analyzed using a polymerase chain reaction with specific primers. We divided the participants into two groups based on their L haplotype: the SS group and the SL and LL group. We performed single and multiple regression analyses to investigate the associations between MADRS improvement and paroxetine plasma concentrations or other covariates for each group.

Results

There were no significant differences between the two groups with regard to demographic or clinical data. In the SS group, the paroxetine plasma concentration was significantly negatively correlated with improvement in MADRS at week 6. In the SL and LL group, the paroxetine plasma concentration was significantly positively correlated with improvement in MADRS at week 6 according to the results of the single regression analysis; however, it was not significantly correlated with improvement in MADRS at week 6 according to the results of the multiple regression analysis.

Conclusion

Among patients with MDD who do not respond to paroxetine, a lower plasma concentration or a lower oral dose of paroxetine might be more effective in those with the SS genotype, and a higher plasma concentration might be more effective in those with the SL or LL genotype.     

Studies on Production of Biotin by Microorganisms

The utilization of hydrocarbons by microorganisms was studied in many fields, but the production of biotin vitamers by hydrocarbon-utilizing bacteria has never been reported.

We have screened many hydrocarbon-utilizing bacteria which produce biotin vitamers in the culture broth. The effects of cultural conditions on biotin vitamers production by strain 5–2, tentatively assigned to the genus Pseudomonas, were studied.

More than 98% of biotin vitamers produced from hydrocarbons by strain 5–2 was chromatographically determined as desthiobiotin. As nitrogen source, natural nutrients were more effective than inorganic nitrogen sources. The production of biotin vitamers was increased under the condition of good aeration. Exogenous pimelic or azelaic acid enhanced biotin vitamers production by strain 5–2.

The production of biotin vitamers from n-alkanes, n-alkenes or glucose by an isolated bacterium, strain 5-2, tentatively assigned to the genus Pseudomonas, was investigated. Among these carbon sources, n-undecane was the most excellent for biotin vitamers production.

The biosynthetic pathway of biotin vitamers, especially desthiobiotin, from n-undecane was also studied. It was found by thin-layer and gas-liquid chromatographical methods that pimelic and azelaic acids were the main acid components in n-undecane culture.

This result, together with previously reported enhancement of biotin vitamers production by these acids, suggests that pimelic and azelaic acids may be the intermediates of biotin vitamers biosynthesis from n-undecane.     

(Z)- and (E)-12-Tetradecenyl Acetates: Sex Pheromone Components of Oriental Corn Borer (Lepidoptera : Pyralidae)

The female sex pheromone of the oriental corn borer, Ostrinia furnacalis Guenée, was presumed to be composed of (Z)-12-tetradecenyl acetate and its geometrical isomer using electroantennogram technique. From the extracts of female moths, the presence of these compounds in a ratio of ca. 3:2 was confirmed by gas-liquid chromatography and gas-liquid chromatography combined with mass spectrometry in selected ion monitoring mode. Since the male moths were not attracted to mixtures of the two synthetic compounds, the presence of minor component(s) was suggested.     

Quantitative Structure-Activity Relationships for Antifungal 3-(3,5-Dichloropheny)-2,4-imidazolidinediones

The antifungal activity of 441-acyl derivatives of 3-(3,5-dichlorophenyl)-2,4-imidazol- idinedione against Botrytis cinerea, and of 10 1-sulfonyl compounds against Aiternaria kikuchi- ana were assayed by the agar medium dilution method. The structure-activity relationships for the substituents of the acyl and sulfonyl moieties were analyzed with such physicochemical parameters as hydrophobic π, inductive electronic σ₁, and steric E′^c_s and B₁ values by multiple regression. The activity of the acyl derivatives against B. cinerea was related parabolically to the hydrophobicity of the substituents. The stronger the electron-donating power, the larger the overall steric bulkiness, and the smaller the minimum width in the direction perpendicular to the bond axis of the substituents, the greater was the activity. The activity of the sulfonyl derivatives against A. kikuciana was related only to the hydrophobicity of the substituents.     

Adenosine A2A receptor deficiency attenuates the somnogenic effect of prostaglandin D2

Sleep and Biological Rhythms -     

Drp1-dependent mitochondrial fission via MiD49/51 is essential for apoptotic cristae remodeling

Mitochondrial fission facilitates cytochrome c release from the intracristae space into the cytoplasm during intrinsic apoptosis, although how the mitochondrial fission factor Drp1 and its mitochondrial receptors Mff, MiD49, and MiD51 are involved in this reaction remains elusive. Here, we analyzed the functional division of these receptors with their knockout (KO) cell lines. In marked contrast to Mff-KO cells, MiD49/MiD51-KO and Drp1-KO cells completely resisted cristae remodeling and cytochrome c release during apoptosis. This phenotype in MiD49/51-KO cells, but not Drp1-KO cells, was completely abolished by treatments disrupting cristae structure such as OPA1 depletion. Unexpectedly, OPA1 oligomers generally thought to resist cytochrome c release by stabilizing the cristae structure were similarly disassembled in Drp1-KO and MiD49/51-KO cells, indicating that disassembly of OPA1 oligomers is not directly linked to cristae remodeling for cytochrome c release. Together, these results indicate that Drp1-dependent mitochondrial fission through MiD49/MiD51 regulates cristae remodeling during intrinsic apoptosis.