TRANSCRIPTIONAL CONTROL OF PROTEIN SYNTHISIS IN THE DEVELOPING OVARIES OF BOMBYX MORI*

Amino acid incorporation was studied with cell-free extracts and ribosomes prepared from pupal ovaries at different ages of Bombyx mori. Poly(U)-directed ³H-phenylalanine incorporation attained a maximum rate at a certain stage of development, but soon dropped to a low level and was replaced by ³H-leucine incorporation, which was due to endogenous mRNA. The latter incorporation occurred at the stage when actual protein synthesis takes place in the ovaries. “Run-off” of the ribosomes which had a high endogenous activity resulted in an enhancement of the poly(U)-dependent activity. The results indicate that the protein synthesis in the ovary is mainly controlled at the level of mRNA. This was further supported by the fact that the relative amount of an ovarian poly(A)-containing “mRNA” fraction increased in parallel with the endogenous activity.     

Ontogeny of euthecal and metaseptal structures in colonial scleractinian corals

The ontogenetic development of two Recent scleractinian corals, Golaxea fascicularis (Linnaeus) and Acrhelia horrescens (Dana), has been studied in serial thin sections. The origin of the septotheca (a collective term including both eutheca and pseudotheca) is reconsidered. The eutheca is found to be a basic skeletal structure of corals and of primary origin, formed directly from the basal plate, not by the thickening of septa. The eutheca prepares the way for the formation of metasepta. The ontogenetic growth of the metasepta is illustrated. The pseudotheca is formed by fusion of neighbouring septa and is entirely of secondary origin. Its development is occasional. The essential mural structure of oculinid corals with pseudothecal walls is euthecal.     

INHIBITORY EFFECT OF RABBIT SERUM FACTOR ON IN VITRO OOCYTE MATURATION OF THE TELEOST FISH,ORYZIAS LATIPES*

The present study indicates that a factor in rabbit serum inhibits the in vitro steroid- and gonadotropin-induced maturation of oocytes of the teleost fish, Oryzias latipes. Such inhibitory activity could not be recognized in the serum of this fish or in the fluids from mammalian follicles. Passage of the serum inhibitor through a cellulose membrane indicated that it has a molecular weight of less than 3,500. The inhibitory activity on steroid-induced oocyte maturation was not destroyed by heating, by repeated freezing and thawing or by treatment with proteolytic enzymes, lipase or amylases. However, its activity could be removed by extraction with charcoal but not with ethyl ether or toluene. The inhibitory action of the heat-stable and dialyzable serum factor was reversible. The factor appears to exert its inhibitory effect upon the oocyte itself in an early step of maturation, rather than upon the follicle cells.     

The allopolyploid Arabidopsis kamchatica originated from multiple individuals of Arabidopsis lyrata and Arabidopsis halleri

Polyploidization, or genome duplication, has played a critical role in the diversification of animals, fungi and plants. Little is known about the population structure and multiple origins of polyploid species because of the difficulty in identifying multiple homeologous nuclear genes. The allotetraploid species Arabidopsis kamchatica is closely related to the model species Arabidopsis thaliana and is distributed in a broader climatic niche than its parental species. Here, we performed direct sequencing of homeologous pairs of the low-copy nuclear genes WER and CHS by designing homeolog-specific primers, and obtained also chloroplast and ribosomal internal transcribed spacer sequences. Phylogenetic analysis showed that 50 individuals covering the distribution range including North America are allopolyploids derived from Arabidopsis lyrata and Arabidopsis halleri . Three major clusters within A. kamchatica were detected using Bayesian clustering. One cluster has widespread distribution. The other two are restricted to the southern part of the distribution range including Japan, where the parent A. lyrata is not currently distributed. This suggests that the mountains in Central Honshu and surrounding areas in Japan served as refugia during glacial–interglacial cycles and retained this diversity. We also found that multiple haplotypes of nuclear and chloroplast sequences of A. kamchatica are identical to those of their parental species. This indicates that multiple diploid individuals contributed to the origin of A. kamchatica . The haplotypes of low-copy nuclear genes in Japan suggest independent polyploidization events rather than introgression. Our findings suggest that self-compatibility and gene silencing occurred independently in different origins.     

Metabolism of S-methylcysteine and its sulfoxide in Chinese cabbage, Brassica pekinensis Rupr.

The metabolism of sulfur of S-methyl-L-cysteine and ($)S-methyI-L-cysteinesulfoxide in Chinese cabbage was studied. Results showed thatthese sulfur-bearing amino acids are metabolized to cysteineby demethylation. This conclusion is based on; 1) the relativelyhigh recovery of radioactivity in the cysteine of the insolublefraction a short time after the administration of 35S-labeledS-methyl-L-cysteine or ($)S-methyl- L-cysteine sulfoxide; 2)the similarity in the ratios of ³H to ³⁵S in the cysteine ofthe insoluble fraction and in the double-labeled cysteine partof S-methyl-L-cysteine and its sulfoxide fed to detached leavesand 3) the obvious structural relationship between cysteineand its methyl derivative, S-methyl-L-cysteine. Moreover, we ascertained that the sulfur of S-methyl-L-cysteinewas also utilized when supplied to plants; i.e. tomato, tobaccoand cucumber, in which this sulfur amino acid has not been found. (Received June 30, 1971; )     

Induction of Unresponsiveness to Canine Renal Allografts by Total Body Irradiation and Bone Marrow Transplantation

RECENT progress in the definition of the DL-A antigens within a closely bred colony of beagles maintained at the Mary Imogene Basset Hospital (Cooperstown colony) has shown that these antigens are components of the principal system of histocompatibility (DL-A) in the dog^1–3. Dausset and associates⁴ have described the segregation of DL-A antigens in 679 offspring of 151 consecutive matings within the Coopers-town colony. Through methods of backcross analysis, 23 DL-A haplotypes (that is, specificities determined by the DL-A region of one single chromosome) have been identified and the DL-A genotypes of 1,302 offspring of 517 matings in this colony have been defined⁴. This combined genetic and serological information has provided an opportunity to reassess the reported survival rates of allogeneic bone marrow transplantation in serologically matched littermate dogs⁵. We describe here the long term survival of bone marrow transplants and renal allografts obtained from the same donors in nine littermate and three non-littermate recipients selected on the basis of genetic and serological criteria of DL-A compatibility in the Cooperstown colony. The results are contrasted with the survival of twenty-two renal allografts performed in untreated recipients selected on the basis of similar criteria.     

Ganglioside Expression in Melanomas From Japanese Individuals: Unusual Pattern in Two Patients With Metastatic Lesions of Acral Lentiginous Melanomas

Melanoma among Japanese is rare, and differs in its clinical and histological characteristics from that found in Caucasians. In this study, the ganglioside expression of melanoma specimens obtained from Japanese was determined and compared with previously published data on Caucasians. The ganglioside composition of 25 biopsy melanoma specimens, including 13 primary and 12 metastatic lesions, was studied using thin layer chromatography. Four gangliosides (G_M3, G_D3, G_M2, G_D2) were most commonly expressed in melanomas in Japanese. The expression of gangliosides was quite variable in both primary and metastatic melanomas as seen in previous reports. No significant differences were observed between gangliosides from primary and metastatic sites. A new type of ganglioside expression, in which G_M3 was nearly the only ganglioside (>95%), was found in metastatic tumors from two Japanese patients with acral lentiginous melanoma (ALM), which is the most common clinical and histopathological type of melanoma among Japanese but is very unusual among Caucasians. The patterns of expression were similar to those in Caucasians except for the detection of a “new” pattern.     

Dysplastic Melanocytic Nevi Contain High Levels of Pheomelanin: Quantitative Comparison of Pheomelanin/Eumelanin Levels Between Normal Skin,Common Nevi,and Dysplastic Nevi

The degree and type of melanogenesis, i.e., either eumelanin of pheomelanin, has been shown to be a reliable marker for the differentiation of the melanocyte. If exposed to UV light, these two melanins were reported to behave differently; eumelanin was photoprotective whereas pheomelanin was phototoxic to cultured tumor cells. Our previous study indicated that dysplastic melanocytic nevus (DMN) undergoes altered melanogenesis, forming pheomelanosome-like granules. The present study examined chemically the type and degree of melanin synthesized in 31 melanocytic nevi excised from 27 patients as compared with that occurring in the surrounding normal skin. The tissue content of eumelanin and pheomelanin was expressed by the amounts of pyrrole-2,3,5-tricarboxylic acid (PTCA) and aminohydroxyphenylalanine (AHP), respectively. We found that DMN lesions contain significantly higher amounts of pheomelanin than either common melanocytic nevus (CMN) or normal skin. Differences in pheomelanin content between DMN and CMN could not be accounted for by inherently higher levels of pheomelanin within the skin in general from DMN patients. Our present finding substantiates our previous claim that epidermal melanocytes in DMN undergo deranged melanogenesis.