QTL-based analysis of leaf senescence in an indica/japonica hybrid in rice (Oryza sativa L.)

In order to identify quantitative trait loci (QTLs) for leaf senescence and related traits in rice (Oryza sativa L.), we developed two backcross populations, indica/japonica// japonica and indica/japonica//indica, using IR36 as the indica parent and Nekken-2 as the japonica parent. The QTLs were mapped using a set of simple sequence-repeat markers (SSRs) in the BC₁F₁ population. Senescence was characterized in these plants by measuring the leaf chlorophyll content 25 days after flowering (DAF), the reduction in chlorophyll content (the difference between the chlorophyll content at flowering and at 25 DAF), and the number of late-discoloring leaves per panicle at 25 DAF in five plants from each BC₁F₂ line. These plants were moved into a temperature-controlled growth cabinet at the time of flowering and allowed to mature under identical conditions. Eleven QTLs were detected in the two populations. The major of QTLs for senescence were found on the short arm of chromosome 6 and on the long arm of chromosome 9. Of these, one QTL on chromosome 6 and two on chromosome 9 were verified by confirming the effects of the genotypes on the phenotypes of the BC₁F₃ lines. The japonica parent was found to contribute to late senescence at all but one QTL. Based on a comparison of the effects of heterozygotes and homozygotes on the phenotypic values of each QTL genotype, we concluded that the differential senescence observed in the indica-japonica hybrid was not due to over-dominance; rather, it was the result of partial-dominance genes that were donated from either of the parents.     

Close linkage of MEN2A with RBP3 locus in Japanese kindreds

Summary The gene responsible for multiple endocrine neoplasia type 2A (MEN2A) has recently been assigned to the pericentromeric region of chromsome 10 in European Caucasian kindreds by linkage analysis using a DNA marker, interstitial retinol-binding protein 3 (RBP3). We have found tight linkage between the MEN2A and RBP3 loci in Japanese MEN2A kindreds. The maximum lod score is 5.19 at a recombination fraction of 0.00. This result suggests that mutation of a certain gene close to RBP3 is responsible for MEN2A irrespective of ethnic backgrounds.     

Comparison of OspA Serotypes for Borrelia burgdorferi Sensu Lato from Japan,Europe and North America

Sixty-one Borrelia burgdorferi sensu lato strains from various sources (ticks, human, and wild animals) in Japan and two strains from ticks in Far Eastern Russia were classified on the basis of reactivity with 16 monoclonal antibodies (mAb) to outer surface protein A (OspA) and by DNA-DNA hybridization assay. Eleven OspA serotypes (J1 to J11) were recognized among the Japanese and the Far East Russian isolates (serotypes J1 to J9 were identified as B. garinii, serotype J10 was identified as B. afzelii, and serotype J11 corresponded to B. japonica), whereas 7 OspA serotypes for North American and European isolates previously reported (Bettina Wilske et al, J. Clin. Microbiol. 31:340-350, 1993) were not observed except for OspA serotype 2 which showed identical reactivity with OspA serotype J10. This finding provides helpful information for understanding the geographical distribution of Lyme disease borrelia and the development of vaccine and diagnostic tests. In conclusion: 1. B. burgdorferi sensu stricto has not been observed in Japan, 2. Japanese B. afzelii isolates are closely related to those from Europe, 3. B. garinii isolates from Japan are highly heterogeneous and apparently different from European B. garinii isolates.     

Video preference assessment and behavioral management of single-caged Japanese macaques (Macaca fuscata) by movie presentation

Movie presentation can act as an enrichment technique for nonhuman primates, who also show preferences for certain contents. This study investigated the video preferences and effects of movies on behavioral abnormalities in single-caged Japanese macaques. When movie rewards were provided for subjects' touch responses, the subjects maintained the touch responses during 40 2-hr sessions. Although repeated presentation of 1 stimulus set decreased the subject's touch response, changing the stimulus set led to recovery of this response. The subjects showed clear preferences, consistent across 2 different stimulus sets, for movies showing humans or animation (61.1% of total duration). Subjects consistently played movies both with and without their preferred content. The availability of a variety of contents might be important for attracting subjects' interest. The frequency with which monkeys engaged in abnormal behaviors decreased in the experimental (20.9%) and the postexperimental (25.6%) periods compared with the preexperimental period (33.5%). Movie presentations could keep attracting the interest of single-caged monkeys in their visual environment, ameliorating their behavioral abnormalities for some time. In summary, social experience during infancy might influence Japanese macaques' movie preferences.     

RNA cleavage linked with ribosomal action

Ribonuclease LS in Escherichia coli is a potential antagonist of bacteriophage T4. When T4 dmd is mutated, this RNase efficiently cleaves T4 mRNAs and leads to the silencing of late genes, thus blocking T4 growth. We previously found that, when two consecutive ochre codons were placed in the open reading frame of T4 soc, RNase LS cleaved soc mRNA at a specific site downstream of the ochre codons. Here, we demonstrate that RNase LS cleaves soc RNA at the same site even when only a single ochre codon is present or is replaced with either an amber or an opal codon. On the other hand, disruption of the Shine-Dalgarno sequence, a ribosome-binding site required for the initiation of translation, eliminates the cleavage. These results strongly suggest that RNase LS cleaves in a manner dependent on translation termination. Consistent with this suggestion, the cleavage dependency on an amber codon was considerably reduced in the presence of amber-codon-suppressing tRNA. Instead, two other cleavages that depend on translation of the region containing the target sites occurred farther downstream. Additional analysis suggests that an interaction of the ribosome with a stop codon might affect the site of cleavage by RNase LS in an mRNA molecule. This effect of the ribosome could reflect remodeling of the high-order structure of the mRNA molecule.     

TRIC-A channels in vascular smooth muscle contribute to blood pressure maintenance

TRIC channel subtypes, namely TRIC-A and TRIC-B, are intracellular monovalent cation channels postulated to mediate counter-ion movements facilitating physiological Ca(2+) release from internal stores. Tric-a-knockout mice developed hypertension during the daytime due to enhanced myogenic tone in resistance arteries. There are two Ca(2+) release mechanisms in vascular smooth muscle cells (VSMCs); incidental opening of ryanodine receptors (RyRs) generates local Ca(2+) sparks to induce hyperpolarization, while agonist-induced activation of inositol trisphosphate receptors (IP(3)Rs) evokes global Ca(2+) transients causing contraction. Tric-a gene ablation inhibited RyR-mediated hyperpolarization signaling to stimulate voltage-dependent Ca(2+) influx, and adversely enhanced IP(3)R-mediated Ca(2+) transients by overloading Ca(2+) stores in VSMCs. Moreover, association analysis identified single-nucleotide polymorphisms (SNPs) around the human TRIC-A gene that increase hypertension risk and restrict the efficiency of antihypertensive drugs. Therefore, TRIC-A channels contribute to maintaining blood pressure, while TRIC-A SNPs could provide biomarkers for constitutional diagnosis and personalized medical treatment of essential hypertension.     

Chimpanzee mothers at Bossou, Guinea carry the mummified remains of their dead infants

The forests surrounding Bossou, Guinea, are home to a small, semi-isolated chimpanzee community studied for over three decades [1]. In 1992, Matsuzawa [2] reported the death of a 2.5-year-old chimpanzee (Jokro) at Bossou from a respiratory illness. The infant's mother (Jire) carried the corpse, mummified in the weeks following death, for at least 27 days. She exhibited extensive care of the body, grooming it regularly, sharing her day- and night-nests with it, and showing distress whenever they became separated. The carrying of infants' corpses has been reported from a number of primate species, both in captivity and the wild [3-7] - albeit usually lasting a few days only - suggesting a phylogenetic continuity for a behavior that is poignant testament to the close mother-infant bond which extends across different primate taxa. In this report we recount two further infant deaths at Bossou, observed over a decade after the original episode but with striking similarities.