In ovo o,p'-DDT exposure induces malformation of reproductive organs and alters the expression of genes controlling sexual differentiation in Japanese quail embryo.

In ovo exposure to o,p'-dichloro-diphenyl-trichloroethane (o,p'-DDT) impairs reproduction by inducing malformation of the reproductive organs in birds, although the mechanism remains unclear. Here, we examined the effects of o,p'-DDT on the development of the reproductive organs, the expression of genes controlling sexual differentiation, and the plasma concentrations of testosterone and estradiol in Japanese quail embryos. o,p'-DDT-containing sesame oil was injected into the yolk sac on Embryonic Day (E) 3 at a dose of 500, 2,000, or 8,000 μg per egg.

Rice Mutants Lacking Starch Synthase I or Branching Enzyme IIb Activity Altered Starch Biosynthetic Protein Complexes.

Amylopectin, the major component of starch, is synthesized by synergistic activity of multiple isozymes of starch synthases (SSs) and branching enzymes (BEs). The frequency and length of amylopectin branches determine the functionality of starch. In the rice endosperm, BEIIb generates short side chains of amylopectin and SSI elongates those branches, which can be further elongated by SSIIa.

Amylopectin biosynthetic enzymes from developing rice seed form enzymatically active protein complexes.

Amylopectin is a highly branched, organized cluster of glucose polymers, and the major component of rice starch. Synthesis of amylopectin requires fine co-ordination between elongation of glucose polymers by soluble starch synthases (SSs), generation of branches by branching enzymes (BEs), and removal of misplaced branches by debranching enzymes (DBEs). Among the various isozymes having a role in amylopectin biosynthesis, limited numbers of SS and BE isozymes have been demonstrated to interact via protein-protein interactions in maize and wheat amyloplasts.

Deficiencies in both starch synthase IIIa and branching enzyme IIb lead to a significant increase in amylose in SSIIa-inactive japonica rice seeds.

Starch synthase (SS) IIIa has the second highest activity of the total soluble SS activity in developing rice endosperm. Branching enzyme (BE) IIb is the major BE isozyme, and is strongly expressed in developing rice endosperm. A mutant (ss3a/be2b) was generated from wild-type japonica rice which lacks SSIIa activity.

Relationships between starch synthase I and branching enzyme isozymes determined using double mutant rice lines.

Background: Starch is the most important carbohydrate in plant storage tissues. Multiple isozymes in at least four enzyme classes are involved in starch biosynthesis. Some of these isozymes are thought to interact and form complexes for efficient starch biosynthesis.

Variation in allometry and tree architecture among Symplocos species in a Japanese warm-temperate forest.

We compared tree architecture and allometry among five Symplocos species (Symplocos myrtacea, Symplocos lancifolia, Symplocos lucida, Symplocos glauca, and Symplocos theophrastiifolia) in a Japanese warm-temperate forest to understand the causes of interspecific variations in these characteristics. S. lancifolia, S.