Phylogenetic analyses of Japanese species of Phyllosticta sensu stricto

Although the genus concept of Phyllosticta s. str. (teleomorph: Guignardia) as defined by van der Aa is widely accepted, the species concept is still controversial because it is often based on the morphology on host plants. In this study, the culture characteristics within Phyllosticta s.str. were examined, and the phylogenetic relationships among Japanese species of Phyllosticta s.str. and its teleomorph Guignardia were analyzed using 18S rDNA sequences. Phyllosticta s. str. formed a monophyletic clade. ITS-28S rDNA sequences extracted from fungal cultures derived from various host plants were divided into two subgroups. The first group included cultures from a wide range of host plants and were mainly derived as endophytes from a symptom-less plant. In the second group, cultures from each host plant genus formed distinct clades; these were often isolated as leaf pathogens from diverse plants. Isolates belonging to the first lineage generally grew faster on oatmeal agar. To classify species of Phyllosticta it is necessary to consider an integrated approach such as molecular phylogeny, host plant, colony growth, symptoms, and morphological characteristics of the conidiomata.     

Can small male shrimps achieve copulation in the presence of larger ones?

The capacity for insemination and competitive ability of small males of the partially protandrous alpheid shrimpAthanas kominatoensis Kubo which lives in symbiosis with the Japanese purple sea urchinAnthocidaris crassispina (A. Agassiz) were examined. Although male shrimps 1.5 mm in carapace length or larger produced sperm, it was not until they grew to 2.4 mm that they became functional. Males lost their insemination ability when their endopodite (or the whole) of the 2nd pleopods were amputated. The amputation of the 5th pleopods did not affect the insemination ability. The males also lost insemination ability after being infected by 2 species of Isopod ectoparasites, probably because of the transformation of the 2nd pleopods. Small males were shown to be able to achieve copulation in cohabitation experiments with amputated or parasitized large males. The total parasite infection rate in the field was highest in December and lowest in May. From August to October, when the small and large males coexisted, on the average 15.9% of large males were infected and transformed by the parasites. The presence of parasites offers the small males an opportunity for reproduction and is thought to play an important role in the evolution of protandry in this shrimp.     

Activated Hepatic Stellate Cells Are Dependent on Self-collagen,Cleaved by Membrane Type 1 Matrix Metalloproteinase for Their Growth

Stellate cells are distributed throughout organs, where, upon chronic damage, they become activated and proliferate to secrete collagen, which results in organ fibrosis. An intriguing property of hepatic stellate cells (HSCs) is that they undergo apoptosis when collagen is resolved by stopping tissue damage or by treatment, even though the mechanisms are unknown. Here we disclose the fact that HSCs, normal diploid cells, acquired dependence on collagen for their growth during the transition from quiescent to active states. The intramolecular RGD motifs of collagen were exposed by cleavage with their own membrane type 1 matrix metalloproteinase (MT1-MMP). The following evidence supports this conclusion. When rat activated HSCs (aHSCs) were transduced with siRNA against the collagen-specific chaperone gp46 to inhibit collagen secretion, the cells underwent autophagy followed by apoptosis. Concomitantly, the growth of aHSCs was suppressed, whereas that of quiescent HSCs was not. These in vitro results are compatible with the in vivo observation that apoptosis of aHSCs was induced in cirrhotic livers of rats treated with siRNAgp46. siRNA against MT1-MMP and addition of tissue inhibitor of metalloproteinase 2 (TIMP-2), which mainly inhibits MT1-MMP, also significantly suppressed the growth of aHSCs in vitro. The RGD inhibitors echistatin and GRGDS peptide and siRNA against the RGD receptor αVβ1 resulted in the inhibition of aHSCs growth. Transduction of siRNAs against gp46, αVβ1, and MT1-MMP to aHSCs inhibited the survival signal of PI3K/AKT/IκB. These results could provide novel antifibrosis strategies.