D-Glutamic acid-induced muscle contraction in the silkworm, Bombyx mori

Agonists for muscle contraction in silkworms were screened by injecting test solutions into the hemolymph of decapitated silkworm larvae. Kainic acid, a glutamate receptor agonist, and D-glutamic acid induced muscle contractions, and D-aspartic acid was partially effective, whereas NMDA and AMPA, representative mammalian glutamate receptor agonists, did not induce contraction. L-Glutamic acid inhibited the kainic acid or D-glutamic acid-induced contraction. Amino acid analysis revealed that 3% of the total glutamic acid in the silkworm hemolymph is D-glutamic acid. These results suggest that d-glutamic acid acts physiologically as an agonist for muscle contraction in silkworms, and that L-glutamic acid functions as an inhibitor.     

Clinical Features and Treatment Modes of Mandibular Fracture at the Department of Oral and Maxillofacial Surgery,Shimane University Hospital,Japan

Background

The number of elderly patients with maxillofacial trauma is rapidly increasing due to active lifestyles and longevity. Shimane prefecture has the fastest growing proportion of elderly individuals in Japan. The aim of this study was to reveal the distinctive features and treatment modes of mandibular fracture treatment mode in patients requiring hospitalization at the Department of Oral and Maxillofacial Surgery, Shimane University Hospital, Japan.

Patients and Methods

Patient age, sex, period between injury and first consultation, years since injury, cause of injury, fracture site, treatment, and duration of hospitalization were evaluated. Univariate Poisson regression, relative risk with 95% confidence interval based on the Wald test, Fisher’s exact test, and Kruskal-Wallis test were used to explore associations among clinical and demographic variables.

Results

In total, 305 patients were diagnosed with and hospitalized for mandibular fracture from 1980 to 2010. Younger age increased the risk for mandibular fracture. Incidence was higher in males than females, particularly in the young, but the male to female ratio decreased with age. The period until first hospital consultation decreased progressively over the study period. Fall was a much more frequent cause in patients aged ≥60 than in those aged <60 years. Mandibular fracture with condyle, symphysis, and angle involvement were most common and were associated with sex, age, and treatment mode. Length of hospitalization has decreased since 1980.

Conclusion

In our department, patients aged ≥60 years accounted for a greater proportion of mandibular fracture cases than in many previous studies, reflecting the greater proportion of elderly residents in Shimane prefecture.     

Effects of tryptic digestion on the enzymatic activites of chicken gizzard myosin.

Tryptic digestion of gizzard myosin resulted in the degradation of the 20K light chain (G1) to its 17K fragment, which could not be phosphorylated. The rapid loss of Ca2+-dependent activation of actomyosin ATPase activity accompanied the degradation of G1. Increase in the Ca2+-ATPase activity and decrease in the EDTA-ATPase activity of myosin accompanied the degradation of myosin heavy chain, but not the cleavage of G1.     

Fluorescent tracer method for protein SH groups: III. Use ofN-(7-dimethylamino-4-methyleoumarinyl) malelmide as a tracer of cysteine-containing peptides

We studied whetherN-(7-dimethylamino-4-methyleoumarinyl) maleimide (DACM) could be used as a fluorescent tracer for the purification and analysis of cysteine-containing peptides. An addition product of DACM with SH compound was stable at room temperature in the solution of pH 9.0 and in 50% acetic acid. However, it was hydrolyzed when heated at 110°C for 48 h in 6n HCl. On filter paper, 1 pmol of the addition product in a spot 3 mm in diameter was visible under ultraviolet illumination. The addition product was also stable on filter paper for at least several months after spotting. The elution velocity of the addition products with low molecular weight SH compounds in the Sephadex G-25 column was low considering their molecular weights. However, in general, the elution velocity increased with an increase in the molecular weight of the addition product. The addition product with a peptide having cysteinyl residue at an N-terminal showed another abnormally retarded peak in elution profile which presumably corresponded to a cyclic compound, a thiazane derivative. However, it was shown on the C-terminal tryptic peptide of actin (Cys Phe) that the conversion to a thiazane derivative could be avoided by hydrolyzing the succinimide portion of DACM at pH 9.0 before digestion. The R_f values on paper chromatography for the addition products also depended on their molecular weights. However, the hydrophobicity of the coumarin portion of DACM and of the side chain of amino acid residues also affected the value. It was concluded that DACM was a valuable reagent for the purification and analysis of cysteine-containing peptides.     

Phosphorylation of retinoblastoma-related protein by the cyclin D/cyclin-dependent kinase complex is activated at the G1/S-phase transition in tobacco

In mammals, D-type cyclin-associated kinases mainly regulate the G1/S transition by phosphorylating the retinoblastoma (Rb) protein. We previously demonstrated that in tobacco, cyclin D (Nicta; CycD3;3) is complexed with the PSTAIRE-containing cyclin-dependent kinase (CDKA) from tobacco. Here, we show that Nicta; CycD3;3-associated kinases phosphorylate both the tobacco Rb-related protein (NtRb1) and histone H1. Although NtRb1 kinase activity was detected only during the middle G1- to early S-phase, histone H1 kinase activity was observed as two peaks in G1- to S-phase and G2/M- to M-phase. Importantly, we show that the proportion of cells in the G1-phase was reduced in transgenic Bright Yellow-2 cells overexpressing Nicta; CycD3;3-GFP. Mutational analyses revealed that phosphorylation of Thr-191 in Nicta; CycD3;3 possibly is required for both full kinase activity and localization predominantly to the nucleus. These data suggest that Nicta; CycD3;3 acts as a rate-limiting regulator in the G1/S transition by forming active complexes with CDKA or its related kinases to phosphorylate Rb-related protein and potentially plays a novel role during G2/M and mitosis.     

X radiation up-regulates the occurrence and the multiplicity of invasive carcinomas in the intestinal tract of Apc(min/+) mice

X rays are well known to cause genetic damage and to induce many types of carcinomas in humans. The Apc(min/+) mouse, an animal model for human familial adenomatous polyposis (FAP), contains a truncating mutation in the APC gene and spontaneously develops intestinal adenomas. To elucidate the role of X rays in the development of intestinal tumors, we examined the promotion of carcinogenesis in X-irradiated Apc(min/+) mice. Forty out of 77 (52%) X-irradiated Apc(min/+) mice developed adenocarcinomas that invaded the proprial muscle layer of the small intestine; 24 of 44 (55%) were in males, and 16 of 33 (49%) were in females. In contrast, invasive carcinomas were detected in the small intestines of only 13 of 64 (20%) nonirradiated Apc(min/+) mice; nine of 32 (28%) were in males and four of 32 (13%) were in females. These differences between X-irradiated and nonirradiated Apc(min/+) mice in the occurrence of invasive intestinal carcinomas were statistically significant (P < 0.05 for males, P < 0.005 for females). In wild-type mice, invasive carcinomas were not detected in either X-irradiated or nonirradiated mice. Apc(min/+) mice had many polyps in the large intestine with or without X irradiation; there was no difference in the number of polyps between the two groups. Also, invasive carcinomas were not detected in the large intestine with or without irradiation. The occurrence of mammary tumors, which was observed in Apc(min/+) mice, was found to be increased in irradiated Apc(min/+) mice (P < 0.01). Apc(min/+) mice had many polyps in the small and large intestines with or without X irradiation. X-irradiated Apc(min/+) mice had highly invasive carcinomas in the small intestine with multiplicities associated with invasiveness. Our results suggest that X radiation may promote the invasive activity of intestinal tumors in Apc(min/+) mice.     

Molecular analysis of external genitalia formation: the role of fibroblast growth factor (Fgf) genes during genital tubercle formation

The molecular mechanisms underlying the development of the external genitalia in mammals have been very little examined. Recent gene knockout studies have suggested that the developmental processes of its anlage, the genital tubercle (GT), have much in common with those of limb buds. The Fgf genes have been postulated as regulating several downstream genes during organogenesis. Fgf8 was expressed in the distal urethral plate epithelium of the genital tubercle (GT) together with other markers such as the Msx1, Fgf10, Hoxd13 and Bmp4 expressed in the mesenchyme. To analyze the role of the FGF system during GT formation, an in vitro organ culture system was utilized. It is suggested that the distal urethral plate epithelium of GT, the Fgf8-expressing region, regulates the outgrowth of GT. Ectopic application of FGF8 beads to the murine GT induced mesenchymal gene expression, and also promoted the outgrowth of the GT. Experiments utilizing anti-FGF neutralizing antibody suggested a growth-promoting role for FGF protein(s) in GT outgrowth. In contrast, despite its vital role during limb-bud formation, Fgf10 appears not to be primarily essential for initial outgrowth of GT, as extrapolated from Fgf10(-/-) GTs. However, the abnormal external genitalia development of Fgf10(-/-) perinatal mice suggested the importance of Fgf10 in the development of the glans penis and the glans clitoridis. These results suggest that the FGF system is a key element in orchestrating GT development.     

Structural Basis of Heterochromatin Formation by Human HP1

1. Download high-res image (278KB)
2. Download full-size image