IN VITRO DIFFERENTIATION OF CHICK EMBRYONIC LENS EPITHELIAL CELLS INTO FIBER CELLS

The processes of fiber-cell formation in the lens epithelium of 9-day-old chick embryo in vitro were studied.
Mitotic activity was enhanced during the first 12 hr, but with a drop at the 4th hour of cultivation. After the 24th hour, when the cells began to elongate, almost no mitotic figures or incorporation of ³H-thymidine into the nuclei were observed.
α- and δ-crystallin were contained in and synthesized by the newly isolated lens epithelium. The content and syntheses had diminished by the 12th hour.
In the earlier phase of cultivation, both fiber cell formation and crystallin synthesis were suppressed by treatment with Actinomycin D, but after the 12th hour they were resistant to the antibiotic.
The correlation between cell division and fiber-cell differentiation in the lens epithelium in vitro is discussed and compared with that reported in Wolffian lens regeneration and in developing bovine lens.     

Chemical Factors Affecting Palmelloid-Forming Activity of Chloroplatinic Acid on Chlamydomonas eugametos

In order to elucidate the physiological mechanism of palmelloid formation of the unicellular green alga Chlamydomonas eugametos by chloroplatinic acid, the factors causing inhibition of the palmelloid formation were studied in various media. Chloroplatinic acid lost its palmelloid-forming effect in the presence of nitrite ion and amines having a second functional group. Nitrate, potassium, and sodium ions and monofunctional amines were without influence on the effect of chloroplatinic acid. These results indicate that the active form of platinum (IV) may undergo ligand substitution, the resulting complex being unable to cause palmelloid formation.     

Ciliary Membranes and Mating Substances in Paramecium caudatum

SYNOPSIS Cilia detached from mating reactive cells of Paramecium caudatum were fractionated for the purpose of identifying the structural component bearing mating substances. Purified axoneme fractions had no mating reactivity. The membrane fraction obtained by dialyzing against a solution of Tris-EDTA (0.1 m m EDTA, 1 m m Tris-HCI, pH 7.6) and 0.6 m KCI, and then by centrifuging over 40% (w/v) sucrose was strongly reactive. No mating reactivity was detected in the soluble fractions containing axonemal and matrix proteins. The results indicate that the mating substances in active from are localized only on the ciliary membranes.     

Characterization of microsatellite loci for a barrenwort species (Epimedium diphyllum,Berberidaceae)

Microsatellites were identified and characterized from Epimedium diphyllum, a species of barrenworts, both attractive garden plants and valuable medicinal plants. Some Japanese species of Epimedium are threatened with extinction, and are listed in the Red Data Book of plants in Japan. Natural hybrid zones also have been reported among some taxa of Japanese Epimedium. We developed eight polymorphic microsatellite primers for population genetic analyses of E. diphyllum. The numbers of alleles per locus ranged from 10 to 20, with observed levels of heterozygosity between 0.85 and 1.00. These primer sets yielded amplification in the other three Japanese Epimedium. These markers will be valuable for conservation genetics, evolutionary biology, pharmacognostic study, and horticultural study of Epimedium.     

Morphological and genetic differentiation in Isodon umbrosus by altitudinal variation in bumblebee pollinator assemblages

The corolla tube length of the bumblebee-pollinated plant Isodon umbrosus shows conspicuous geographical variation, corresponding with the proboscis length of its bumblebee pollinators across its distributional range. We hypothesized that altitudinal variation in the pollinator assemblage is a principal factor mediating morphological and genetic differentiation among I. umbrosus populations. We examined determinants of the morphological and genetic differentiation of Isodon umbrosus by analyzing floral morphology and allozyme variation across the distributional range. A reanalysis of previous data confirmed that altitude was a good indicator of pollinator assemblages. Corolla tube length was highly variable among the 15 study populations, and genetic differentiation among the populations ( G _ST = 0.360) was also highly significant. The differentiation in corolla tube length was explained by altitudinal difference, a proxy of the difference in pollinator assemblages. Genetic differentiation among populations also tended to be affected by the same factor, but statistical support was weak. To better understand the mechanisms responsible for morphological and genetic differentiation in I. umbrosus , we need to investigate altitudinally different populations over a narrower geographical scale.     

INDUCTION OF CHROMOSOME MOTION IN THE GLYCEROL-ISOLATED MITOTIC APPARATUS: NUCLEOTIDE SPECIFICITY AND EFFECTS OF ANTIDYNEIN AND MYOSIN SERA ON THE MOTION*

Chromosome motion in glycerol-isolated mitotic apparatus (MA) of sea urchin and starfish eggs was investigated with respect to nucleotide specificity and the effects of antisera against tryptic fragment (Fragment A) of flagellar dynein and starfish egg myosin. The motion was highly specific for ATP. GTP, ITP, CTP, UTP, and ADP caused no displacement of the chromosomes towards the poles. The anti-Fragment A serum completely inhibited chromosome motion in the MA of the sea urchin egg, while antiserum against starfish egg myosin as well as its γ-globulin fraction did not inhibit the motion in the isolated MA of the starfish egg, suggesting that chromosome motion depends upon dynein-microtubule but not upon myosin-actin interaction. In addition, colchicine completely suppressed the chromosome motion in vitro.     

Changes in Sugar Content during Cold Acclimation and Deacclimation of Cabbage Seedlings

The relationship between freezing tolerance and sugar contentin cabbage seedlings was investigated. Seedlings exposed tonon-freezing low temperature (5 °C) acquired freezing tolerancedown to -6 °C. The degree of freezing tolerance increasedwith duration of exposure to low temperature (up to 10 d). Sucrose,glucose, fructose and myo -inositol were detected as solublesugars in cabbage leaves, and all soluble sugars, except formyo -inositol, and starch increased gradually during cold acclimationsuch that their levels were positively correlated with the degreeof freezing tolerance. The induced freezing tolerance was attributednot to ontogenetic changes but to cold acclimation. However,the induced freezing tolerance was lost after only 1 d of deacclimationat control temperatures, and this change was associated witha large reduction in sugar content. These results reveal that the sugar content of cabbage leavesis positively correlated with freezing tolerance. Brassica oleracea L.; cabbage; cold acclimation; deacclimation; freezing tolerance; sugars