Cystathionine Accumulation in Various Regions of Brain of DL-Propargylglycine-Treated Rats

The contents of cystathionine and taurine, as well as cystathionine beta-synthase activity in various regions of the brains of normal and DL-propargylglycine-treated rats, were measured. The content of cystathionine in each region of brain increased gradually from 0.5 mg to 20 mg/200 g body weight in relation to the dose of DL-propargylglycine. Cystathionine was found to be unevenly distributed in brains of both normal and DL-propargylglycine-treated rats. On the other hand, the activity of cystathionine beta-synthase was evenly distributed in various regions of normal rat brain, and was unaltered following treatment of rats with DL-propargylglycine. The concentration of taurine was similarly unaffected by DL-propargylglycine injection.     

Unusual metabolism of sulfur-containing amino acids in rats treated with DL-propargylglycine

S-(2-Hydroxy-2-carboxyethyl)homocysteine, S-(3-hydroxy-3-carboxy-n-propyl)-cysteine, N-acylated S-(beta-carboxyethyl)cysteine, and N-acylated S-(3-hydroxy-3-carboxy-n-propyl) cysteine were excreted in the urine after DL-propargylglycine treatment. Cystathionine was also accumulated in several tissues of DL-propargylglycine-treated rats. N-Monoacetylcystathione was found in the liver of rats and was also detected in the kidney and serum. Cystathionine gamma-lyase activity in liver decreased to about 4% of that of control rats 24 h after the DL-propargylglycine injection, and alanine aminotransferase activity decreased to about 35% of that of control rats. On the other hand, aspartate aminotransferase and cystathionine beta-synthese activity did not show significant changes from those of control rats. The ability of normal tissues to synthesize cystathionine utilizing cystathionine beta-synthase was 1.98 +/- 0.40 mumol/min/g in liver, 0.61 +/- 0.13 in kidney, and 0.18 +/- 0.015 in brain. The maximal contents of cystathionine in rat tissues and the administered amounts of DL-propargylglycine agreed well with the ability to synthesize cystathionine in each tissue.     

Inhibitory effect of tocotrienol on eukaryotic DNA polymerase lambda and angiogenesis

Tocotrienols, vitamin E compounds that have an unsaturated side chain with three double bonds, selectively inhibited the activity of mammalian DNA polymerase lambda (pol lambda) in vitro. These compounds did not influence the activities of replicative pols such as alpha, delta, and epsilon, or even the activity of pol beta which is thought to have a very similar three-dimensional structure to the pol beta-like region of pol lambda. Since delta-tocotrienol had the strongest inhibitory effect among the four (alpha- to delta-) tocotrienols, the isomer's structure might be an important factor in the inhibition of pol lambda. The inhibitory effect of delta-tocotrienol on both intact pol lambda (residues 1-575) and a truncated pol lambda lacking the N-terminal BRCA1 C-terminus (BRCT) domain (residues 133-575, del-1 pol lambda) was dose-dependent, with 50% inhibition observed at a concentration of 18.4 and 90.1microM, respectively. However, del-2 pol lambda (residues 245-575) containing the C-terminal pol beta-like region was unaffected. Tocotrienols also inhibited the proliferation of and formation of tubes by bovine aortic endothelial cells, with delta-tocotrienol having the greatest effect. These results indicated that tocotrienols targeted both pol lambda and angiogenesis as anti-cancer agents. The relationship between the inhibition of pol lambda and anti-angiogenesis by delta-tocotrienol was discussed.     

Group Structure,Nest Size and Reproductive Success in the Cooperatively Breeding Cichlid Julidochromis ornatus: A Correlation Study

The effect of group size on reproductive success has long been studied in cooperatively breeding species, as it might provide an adaptive explanation for group‐living in social species. Numerous studies have shown positive effects of subordinates on reproductive success (‘helper effect’), but these studies have also revealed the importance of controlling statistically, or experimentally, for the effect of other factors that might affect reproductive success. Here, we first examine the relationships between group size, body size of group members and nest size in the cooperatively breeding cichlid Julidochromis ornatus, in which unrelated helpers frequently participate in reproduction and their breeding nests inside rock crevices may be crucial for reproduction and survival of all group members. Then, we subsequently investigate the relationship between group size and reproductive success, while controlling for these factors. The results showed that group size was significantly related to body size of group members rather than nest size; and larger breeders had larger helpers. It was found that group size significantly increased group reproductive output. More importantly, reproductive success of male breeders did not depend on the presence of mature helpers, whereas female reproductive success increased when two males assisted her and tended to decrease when two females bred cooperatively. We conclude that breeding groups of J. ornatus have size hierarchical societies that relate to group size, and group composition of genetically unrelated and co‐breeding members affects their reproductive success.     

Testis size depends on social status and the presence of male helpers in the cooperatively breeding cichlid Julidochromis ornatus

Cooperatively breeding animals, in which helpers may participatein reproduction with dominant breeders, are ideal species forexamining intraspecific variation in testis size because theyoften exhibit both monogamous breeding (low risk of sperm competition)and polyandrous breeding (high risk) within a population. However,little is known about testis investment as a result of spermcompetition in these animals. The substrate-brooding cichlidfish Julidochromis ornatus has a cooperatively breeding system,in which some males mate monogamously and other males reproduceas dominant breeders or helpers within cooperatively breedinggroups, in which male helpers frequently sire young. We examinedthe relationship between testis investment and male social statusin relation to the risk of sperm competition. As predicted fromsperm competition models, in groups with male helpers, boththe male breeders and the male helpers invested more in testesmass, compared to breeding males without male helpers. We alsofound a positive relationship between the testes mass of malebreeders and their male helpers, suggesting that males increasetheir investment in reproductive capability under the risk ofsperm competition. Sperm competition models also predict thatlarger testes are associated with increased siring success.Our paternity analysis supported this prediction; we found apositive relationship between testis investment by male helpersand the number of offspring they sired.