A low body-color regulating ability of spotted halibut Verasper variegatus: Evaluation of the roles of melanin-concentrating hormone and proopiomelanocortin systems

In teleosts, melanin-concentrating hormone (MCH) induces body brightening. On the other hand, α-melanophore-stimulating hormone (α-MSH), derived from the precursor proopiomelanocortin (POMC), leads to body darkening. In many teleosts, the expression level of pmch is high in light backgrounds, while that of pomc is low in dark backgrounds. In the present study, we investigated the ability of spotted halibut Verasper variegatus to regulate body coloration. Intraperitoneal administration of MCH resulted in a dose-dependent brightening of body color. The body color and brain contents of pmch1 and pmch2 in spotted halibut acclimated to the black or white background were not almost affected by background color. In addition, pituitary mRNA levels of pomc-a, pomc-b, and pomc-c genes in fish acclimated to the white background often exceed those levels of fish kept under the black background. These results suggest that the weak response of expression levels of pmch genes in response to background color is a factor in the blunt ability of spotted halibut to regulate body color. The different profiles of pomc gene expression to background color compared to that reported in other teleosts may be another factor for the weak ability of body color change in the spotted halibut.

     

Impact of a 5-year winter cover crop rotational system on the molecular diversity of arbuscular mycorrhizal fungi colonizing roots of subsequent soybean

The impact of winter cover crops, specifically wheat (Triticum aestivum L.), red clover (Trifolium pratense L.), and rapeseed (Brassica napus L.) or winter fallow, on community composition of arbuscular mycorrhizal fungi (AMF) in subsequent soybean roots was investigated in a 5-year field trial on andosolic soils in Japan. Soybean roots were sampled at full-flowering and analyzed for AMF communities using a partial LSU rDNA region. Phylogenetic analysis detected 22 AMF phylotypes, including eight Glomus, three Gigaspora, two Scutellospora, three Acaulospora, two Rhizophagus, and one of Funneliformis, Diversispora, Paraglomus, and an unknown glomeromycete in the roots. The 5-year rotation of different winter cover crops or winter fallow did not impact the molecular diversity of AMF communities colonizing the roots of subsequent soybean. In all of the rotations, Glomus and Gigaspora phylotypes were common to soybean roots over the 5-year period. Redundancy analysis (RDA) demonstrated that AMF communities in the roots of subsequent soybean were not significantly different among winter cover crop rotations or fallow. However, AMF communities in soybean roots were clearly influenced by rotation year suggesting that climate or other environmental factors were more important than winter cover cropping system management.