Alate differentiation and compound-eye development in the dry-wood termite <Emphasis Type="Italic">Neotermes koshunensis</Emphasis> (Isoptera,Kalotermitidae)

In social insects, caste-specific characters develop in the postembryonic differentiation processes. However, the mechanisms of caste-specific organ development have yet to be elucidated. In order to obtain insights into the relationship between caste differentiation and the regulation of organ development, we determined the caste-developmental pathway and observed compound-eye development accompanying alate differentiation in the dry-wood termite, Neotermes koshunensis. As previously reported in other Neotermes, this species has a linear caste-developmental pathway, comprising six larval- and two nymphal-instar stages. Although the apparent eye formation occurs during the last nymphal stages, just prior to the imaginal molt, individuals possess eye primordia from the first larval-instar stage. The outer morphological structure of the eye was observed from the third larval-instar stage. The detailed differentiation of cells constituting ommatidia appeared to occur in relatively young larval instars (fourth stage), although the pigmentation of pigment cells and detailed structural formation of ommatidia occurred during the final stage of alate development, i.e., during the late second nymphal-instar stage. This suggests that eye development is arrested in the larval stages, and then resumed during the late nymphal stage to complete functional eye formation, which is required for nuptial flight. In comparison to major hemimetabolous insects, which possess functional compound eyes even at the first instar larva, this termite species shows the heterochronic shift in terms of compound-eye development. Received 20 March 2006; revised 24 September 2006; accepted 4 October 2006.     

Phosphorylation of proteins and apoptosis induced by c-Jun N-terminal kinase1 activation in rat cardiomyocytes by H(2)O(2) stimulation

Cytokines and various cellular stresses are known to activate c-Jun N-terminal kinase-1 (JNK1), which is involved in physiological function. Here, we investigate the activation of JNK1 by oxidative stress in H9c2 cells derived from rat cardiomyocytes. H(2)O(2) (100 microM) significantly induces the tyrosine phosphorylation of JNK1 with a peak 25 min after the stimulation. The amount of JNK1 protein remains almost constant during stimulation. Immunocytochemical observation shows that JNK1 staining in the nucleus is enhanced after H(2)O(2) stimulation. To clarify the physiological role of JNK1 activation under these conditions, we transfected antisense JNK1 DNA into H9c2 cells. The antisense DNA (2 microM) inhibits JNK1 expression by 80% as compared with expression in the presence of the sense DNA, and significantly blocks H(2)O(2)-induced cell death. Consistent with the decrease in cell number, we detected condensation of the nuclei, a hallmark of apoptosis, 3 h after H(2)O(2) stimulation in the presence of the sense DNA for JNK1. The antisense DNA of JNK1 inhibits the condensation of nuclei by H(2)O(2). Under these conditions, the H(2)O(2)-induced phosphorylation of proteins with molecular masses of 55, 72, and 78 kDa is blocked by treatment with the antisense DNA for JNK1 as compared with the sense DNA for JNK1. These findings suggest that JNK1 induces apoptotic cell death in response to H(2)O(2), and that the cell death may be involved in the phosphorylations of 55, 72, and 78 kDa proteins induced by JNK1 activation.     

Suppressors of temperature-sensitive mutations in a ribosomal protein gene, rpsL (S12), of Escherichia coli K12

Summary Temperature-sensitive (ts) mutations were isolated within a ribosomal protein gene (rpsL) of Escherichia coli K12. Mutations were mapped by complementation using various transducing phages and plasmids carrying the rpsL gene, having either a normal or a defective promoter for the rpsL operon. One of these mutations, ts118, resulted in a mutant S12 protein which behaved differently from the wild-type S12 on CM-cellulose column chromatography. Suppressors of these ts mutations were isolated and characterized; one was found to be a mutation of a nonribosomal protein gene which was closely linked to the RNAase III gene on the E. coli chromosome. This suppressor, which was recessive to its wild-type allele, was cloned into a transducing phage and mapped finely. A series of cold-sensitive mutations, affecting the assembly of ribosomes at 20°C, was isolated within the purL to nadB region of the E. coli chromosome and one group, named rbaA, mapped at the same locus as the suppressor mutation, showing close linkage to the RNAase III gene.     

The effect of inosine on the post ischemic heart as bio-energy recovering factor in 31P-MRS

Perfused guinea-pig hearts, which were analyzed by 31P-MRS, were subjected to 30 and 60 minute ischemia and reperfused using two perfusates, one containing 200 microM inosine, and the other without inosine. After 4 hour reperfusion with inosine, ATP levels increased to 95.5% of preischemic value (30 minute ischemia) and 76.2% (60 minute ischemia). However, after 4 hour reperfusion without inosine, ATP levels increased only to 72.2% (30 minute ischemia) and to 48.2% (60 minute ischemia). In 60 minute ischemic hearts reperfused with inosine, left ventricular maximal positive dp/dt (LV dp/dt) was improved significantly to 82.4% after 6 hour reperfusion in contrast to hearts reperfused without inosine (43.1%). Administration of inosine was very useful for increasing myocardial gross energy product and improving cardiac performance.     

Increased tolerance to salt stress in the phosphate-accumulating <Emphasis Type="Italic">Arabidopsis</Emphasis> mutants <Emphasis Type="Italic">siz1</Emphasis> and <Emphasis Type="Italic">pho2</Emphasis>

High salinity is an environmental factor that inhibits plant growth and development, leading to large losses in crop yields. We report here that mutations in SIZ1 or PHO2, which cause more accumulation of phosphate compared with the wild type, enhance tolerance to salt stress. The siz1 and pho2 mutations reduce the uptake and accumulation of Na⁺. These mutations are also able to suppress the Na⁺ hypersensitivity of the sos3-1 mutant, and genetic analyses suggest that SIZ1 and SOS3 or PHO2 and SOS3 have an additive effect on the response to salt stress. Furthermore, the siz1 mutation cannot suppress the Li⁺ hypersensitivity of the sos3-1 mutant. These results indicate that the phosphate-accumulating mutants siz1 and pho2 reduce the uptake and accumulation of Na⁺, leading to enhanced salt tolerance, and that, genetically, SIZ1 and PHO2 are likely independent of SOS3-dependent salt signaling.     

Rapid increase of vacuolar volume in response to salt stress

Suspension-cultured cells of mangrove [Bruguiera sexangula (Lour.) Poir.] showed a rapid increase in vacuolar volume under salt stress, although there was no change in the cell volume. The rapid increase in the vacuolar volume was an active process, which followed the activation of the tonoplast H(+)-ATPase and the vacuolar acid phosphatase. The same phenomenon was observed in barley (Hordeum vulgare L. cv. Doriru) root meristematic cells under salt stress but not in pea ( Pisum sativum L.). Increases in vacuolar volume could potentially protect the cytoplasm by decreasing the cytoplasmic volume during the initial phases of salt stress.     

Association between dental health behaviours, mental/physical function and self-feeding ability among the elderly: a cross-sectional survey

Objectives : The aim of this study was to determine the association between dental health behaviour, mental/physical function and self‐feeding ability among the elderly. Subjects : A total of 414 elderly dental patients aged 65 years and older participated in this study. Methods : A survey was carried out for three years and seven months starting in January 1998 at the Chubu National Hospital. The patients or their carers were examined/interviewed about the severity of senile dementia, dental health behaviour, ability to rinse their mouths, ability to manage dentures, and ability to sit at a table during meals. To assess the association with self‐feeding ability among the elderly, cut‐offs were given for these variables, and then the odds ratios were calculated. Results : The strongest association to self‐feeding ability was marked by inability to rinse their own mouth, followed by inability to manage dentures, inability to sit at a table during meals, severe senile dementia and less frequency of toothbrushing. Conclusion : Elderly who have lost the feeding ability often could not maintain their dental health by themselves. Carers must provide not only a feeding service with acknowledgement of aspiration but oral care to prevent dental disease and fatal pneumonia in the elderly.     

‘Initial state’ coordinations reproduce the instant flexibility for human walking

An important feature of human locomotor control is the instant adaptability to unpredictable changes of conditions surrounding the locomotion. Humans, for example, can seamlessly adapt their walking gait following a sudden ankle impairment (e.g., as a result of an injury). In this paper, we propose a theoretical study of the mechanisms underlying flexible locomotor control. We hypothesize that flexibility is achieved by modulating the posture at the beginning of the stance phase—the initial state. Using a walking model, we validate our hypothesis through computer simulations     

Alteration of the sex determining system resulting from structural change of the sex chromosomes in the frog Rana rugosa

Rana rugosa in Japan is divided into four geographical races on the basis of the karyotype of the sex chromosomes: one in which heteromorphic sex chromosomes occur in the female sex (ZW/ZZ-system), another in which they are present in males (XX/XY-system), and the remaining two in which no heteromorphism is seen in either sex. The last two inherit the XX/XY sex determining system. Y and Z chromosomes in the former two are of the same karyotype as the no. 7 chromosomes seen in one of the latter two, whereas X and W are caused by two inversions that occurred in the original Xs (no. 7). In this study, we first attempted to detect the structural difference between the resulting X and W by examining their chiasma formation. The chiasma distribution between X and W was closely similar to that between two Xs, suggesting that the W and X are identical in structure. Regarding the change from XX/XY- to ZW/ZZ-system, the simplest explanation is that the putative female-determining gene(s) on the W grew functionally stronger by inversions. Next, we examined the sex of triploids having two Xs and one Z. The data showed that the triploids with two original Xs and a Z were all male, whereas most of those with two resulting Xs and a Z developed into females as expected. We speculated that the female-determining gene(s) on the resulting X grew mildly stronger functionally by position effect, whereas those on the W grew much stronger for some other reason (e.g., duplication). J. Exp. Zool. 286:313-319, 2000.