Effect of latitude on flavonoid biosynthesis in plants

The growth conditions in different latitudes vary markedly with season, day length, light quality and temperature. Many plant species have adapted well to the distinct environments through different strategies, one of which is the production of additional secondary metabolites. Flavonoids are a widely spread group of plant secondary metabolites that are involved in many crucial functions of plants. Our understanding of the biosynthesis, occurrence and function of flavonoids has increased rapidly in recent decades. Numerous studies have been published on the influence of environmental factors on the biosynthesis of flavonoids. However, extensive long‐term studies that examine the effect of the characteristics of northern climates on flavonoid biosynthesis are still scarce. This review focuses on the current knowledge about the effect of light intensity, photoperiod and temperature on the gene–environment interaction related to flavonoid biosynthesis in plants.     

Mutagenicity of the mycotoxin diacetoxyscirpenol on somatic and germ cells of mice

Genotoxicity of diacetoxyscirpenol (DAS) was studied on laboratory mice after intraperitoneal injection with single and repeated doses. DAS was administrated at three different dose levels (0.5, 0.75, and 1.0 mg/kg body weight). The study was conducted on both somatic and germ cells additional to the sperm morphology analysis. DAS treatment resulted in a significant reduction (P<0.01) in mitotic activity at all levels of doses tested, confirming that DAS is a potent protein and DNA synthesis inhibitor. At somatic cells (bone marrow) both structural and numerical chromosome abnormalities were observed. Single dose treatment showed significant abnormalities only with high dose treatment. In contrast, at repeated dose similar abnormalities were also observed with some significance but no systematic relation between the administrated dose and abnormalities ratio could be settled. In germ cells (testicles), structural and numerical abnormalities were also observed. In general, the frequencies of scored abnormalities at germ cells were lower than that the somatic cells. Sperm count test revealed a decrease in the number of released sperm after toxin treatment. Abnormalities of sperm shape (head and tail) were observed, confirming the positive correlation between cytogenetic damage and sperm abnormality. The results also proved that DAS is a very toxic mycotoxin, in addition to inducing chromosomal abnormalities, it causes a severe inhibition of DNA synthesis which subsequently affects the cell cycle and cell division. A good system for good harvesting practice and good food technology can lower the risk for the consumers.     

Distribution and reproductive success of the Pied Flycatcher Ficedula hypoleuca in relation to forest patch size and vegetation characteristics; the effect of scale

We studied habitat choice, distribution and reproductive success in the Pied Flycatcher Ficedula hypoleuca in relation to the spatial structure of a fragmented forest area. Two hierarchical levels of forest habitat structure were used: (1) forest patch size (macrohabitat) and (2) vegetative structure within forest patches (microhabitat). In spring, both males and females settled preferentially in large and medium-sized forest stands (>1 ha) where breeding density was also higher than in small stands (<1 ha). Stands <5 ha were occupied later, and the proportion of unpaired males was higher there than in large stands (>5 ha). The known age distributions of breeding birds and breeding success were independent of forest patch size. Nest predation rate was not associated with stand size or nest distance from the forest edge. The preference of breeding birds for large forest patches was presumably related to the higher amount of resources (nest sites, mates, food) a large patch can offer for reproduction compared with a small patch. At the microhabitat level, territories of old males were characterized by relatively more deciduous trees that contained more invertebrate food than coniferous tree-dominated territories of yearling males. The reproductive success of old males, as measured by the number of fledged young per male, was higher than that of yearling males. This suggests that the larger body size and blacker plumage of old males possibly contributed to male dominance and that old males excluded younger males from preferred habitats through territorial behaviour. Our results suggest that habitat choice of the Pied Flycatcher was affected by both micro- and macrohabitat. On the basis of settlement pattern, density and reproductive success, the distribution of Pied Flycatchers across forest stands of different sizes followed the ideal-free distribution model, whereas at the microhabitat level, age-related unequal distribution of males followed the ideal-despotic model of Fretwell and Lucas.     

Genetic and morphological evidence for reproductive isolation between sympatric populations of Galaxias (Teleostei: Galaxiidae) in South Island, New Zealand

New Zealand's South Island houses a flock of closely related stream-resident fish taxa (Galaxias vulgaris sensu lato), including a number of species recently described on the basis of subtle morphological differences. The taxonomic status of some members of the species complex remains uncertain. This study examines the degree of reproductive isolation between recently recognized morphotypes from Southland (G. 'southern', flatheads; G. gollumoides, roundheads) which co-occur in Bushy Creek, a tributary of the Mataura R. Although these morphotypes are broadly sympatric in Southland and Stewart Island, Bushy Creek is their only documented zone of contact. Molecular (microsatellite, isozyme and mtDNA markers) and morphological analyses of 139 fish samples across a 500-m transect (seven stations) reveal a cline from predominantly G. 'southern' (N=85) to predominantly G. gollumoides (JV=54), corresponding with a gradual increase in stream gradient. Multivariate analyses of genotypic and morphological data independently reveal distinct clusters that are completely congruent with mtDNA type, suggesting an absence of mtDNA introgression. Our data support the separate species status of G. 'southern' and G. gollumoides under both biological and phylogenetic species concepts. We suggest that the speciation of these taxa occurred in allopatry through independent losses of diadromy, with sympatry resulting from secondary contact.