Opioid receptor-like 1 (ORL1) receptor binding and the biological properties of Ac-Arg-Tyr-Tyr-Arg-Ile-Arg-NH2 and its analogs.

Hexapeptides such as Ac-Arg-Tyr-Tyr-Arg-Ile-Lys-NH(2) and Ac-Arg-Tyr-Tyr-Arg-Trp-Arg-NH(2) have been isolated from a combinatorial peptide library as small peptide ligands for the opioid peptide-like 1 (ORL1) receptor. To investigate the detailed structural requirements of hexapeptides, 25 analogs of these hexapeptides, based on the novel analog Ac-Arg-Tyr-Tyr-Arg-Ile-Arg-NH(2) (1), were synthesized and tested for their ORL1 receptor affinity and agonist/antagonist activity on mouse vas deferens (MVD) tissues. Analog 1 and its Cit(6)-analog (10) were found to possess high affinity to the ORL1 receptor, comparable to that of nociceptin/orphanin FQ, and exhibited potent antagonist activity (pA(2) values of 7.77 for 1 and 7.51 for 10, which are higher than that of [NPhe(1)]nociceptin(1-13)-NH(2) (6.90) on MVD assay. It was also found that the amino acid residue in position 5 plays a key role in agonist/antagonist activity, i.e. an L-configuration aliphatic amino acid is required for potent antagonist activity, while a nonchiral or D-configuration residue produces potent agonist activity. These lines of evidence may provide insight into the mechanisms controlling agonist/antagonist switching in the ORL1 receptor, and may also serve to help developing more potent ORL1 agonists and antagonists.     

Identification of a gene, Desiccate, contributing to desiccation resistance in Drosophila melanogaster

Suitable alterations in gene expression are believed to allow animals to survive drastic changes in environmental conditions. Drosophila melanogaster larvae cease eating and exit moist food to search for dry pupation sites after the foraging stage in what is known as the wandering stage. Although the behavioral change from foraging to wandering causes desiccation stress, the mechanism by which Drosophila larvae protect themselves from desiccation remains obscure. Here, we identified a gene, CG14686 (designated as Desiccate (Desi)), whose expression was elevated during the wandering stage. The Desi expression level was reversibly decreased by transferring wandering larvae to wet conditions and increased again by transferring them to dry conditions. Elevation of Desi expression was also observed in foraging larvae when they were placed in dry conditions. Desi encoded a 261-amino acid single-pass transmembrane protein with notable motifs, such as SH2 and PDZ domain-binding motifs and a cAMP-dependent protein kinase phosphorylation motif, in the cytoplasmic region, and its expression was observed mainly in the epidermal cells of the larval integuments. Overexpression of Desi slightly increased the larval resistance to desiccation stress during the second instar. Furthermore, Desi RNAi larvae lost more weight under dry conditions, and subsequently, their mortalities significantly increased compared with control larvae. Under dry conditions, consumption of carbohydrate was much higher in Desi RNAi larvae than control larvae. Based on these results, it is reasonable to conclude that Desi contributes to the resistance of Drosophila larvae to desiccation stress.     

Plant meristems: <Emphasis Type="Italic">CLAVATA3/ESR</Emphasis>-related signaling in the shoot apical meristem and the root apical meristem

The plant meristems, shoot apical meristem (SAM) and root apical meristem (RAM), are unique structures made up of a self-renewing population of undifferentiated pluripotent stem cells. The SAM produces all aerial parts of postembryonic organs, and the RAM promotes the continuous growth of roots. Even though the structures of the SAM and RAM differ, the signaling components required for stem cell maintenance seem to be relatively conserved. Both meristems utilize cell-to-cell communication to maintain proper meristematic activities and meristem organization and to coordinate new organ formation. In SAM, an essential regulatory mechanism for meristem organization is a regulatory loop between WUSCHEL (WUS) and CLAVATA (CLV), which functions in a non-cell-autonomous manner. This intercellular signaling network coordinates the development of the organization center, organ boundaries and distant organs. The CLAVATA3/ESR (CLE)-related genes produce signal peptides, which act non-cell-autonomously in the meristem regulation in SAM. In RAM, it has been suggested that a similar mechanism can regulate meristem maintenance, but these functions are largely unknown. Here, we overview the WUS–CLV signaling network for stem cell maintenance in SAM and a related mechanism in RAM maintenance. We also discuss conservation of the regulatory system for stem cells in various plant species. S. Sawa is the recipient of the BSJ Award for Young Scientist, 2007.     

Ex vivo intraoperative angiography for rectus abdominis musculocutaneous free flaps

In this study, the vascular architecture of rectus abdominis free flaps nourished by deep inferior epigastric vessels was investigated using an ex vivo intraoperative angiogram. Oblique rectus abdominis free flaps were elevated and isolated from the donor site. In 11 patients, the vascular architecture of these flaps was analyzed before the flap was thinned. Radiographic study identified an average of 2.1 large deep inferior epigastric arterial perforators in each flap. In nine of the 11 flaps, the axial artery was visible. In four flaps, the axial artery originated from the perforator of the lateral branch of the deep inferior epigastric artery; in five others, it originated from the medial branch. In each flap, the angle of the axial perforator from its anterior rectus sheath in the vertical plane was measured; its mean was 50.6 degrees. All flaps survived, although three showed partial necrosis in the distal portions. In two of these three flaps, the axial artery was not visible in the angiograms, and the third revealed a one-sided distribution of axial flap arteries. Using ex vivo intraoperative angiography, the architecture of the individual flap, its axial perforator, and its connecting axial flap vessel could be investigated. This information can help the surgeon safely thin and separate the flap.     

Light and electron microscopic observation on the appearance of immunoreactive LHRH in perinatal rat hypothalamus

Summary The appearance and localization of LHRH were studied in the developing hypothalamus of perinatal rats using the unlabelled antibody method. By light microscopy, immunoreactive LHRH was first detected as brown dots on day 18.5 of gestation in the OVLT and on day 19.5 in the median eminence, respectively. When the median eminence was examined by the preembedding immunohistochemistry technique for electron microscopy, the occurrence of immunoreactive LHRH fibers could be demonstrated on day 18.5. These fibers were thin and very occasionally encountered near the surface of the lateral regions of the median eminence. The axoplasm contained a few immunopositive secretory granules and also extragranular immunoreactive products. With development, a gradual increase was noted both in number and size of nerve fibers with a concomitant accumulation of secretory granules within the axoplasm.A possible physiological significance of LHRH is discussed in relation to the onset of hypothalamo-hypophysial system in fetal life.     

Biosystematic studies inErythronium (Liliaceae-Tulipeae)

The floral biology ofErythronium japonicum has been studied from two approaches: a reinvestigation of its floral morphology and a pollinator case history. The perianth, differentiated into a sepal and petal cycle, has a tubular, but free arrangement basally around a slightly stipitate ovary. The two cycles of stamens with dimorphic filaments are positioned by the differently lobed auricles of the mature sepals and petals. These auricles also form a trap-lid mechanism for the inverted nectary which also has passageways. The perianth parts are highly UV absorbant due to the presence of flavonoids. This pattern contrasts strikingly with the purple trident basal guide lines so prominent in the visible spectrum. The weakly protandrous flowers also have exserted styles, thus functioning to exclude its own pollen and insure outbreeding. These floral adaptations are related specifically to the pollination behavior ofXylocopa appendiculata, and in general to the floral evolution within the genusErythronium. This work was supported in part by the U.S.-Japan Cooperative Science Program Grant GF-41367 and Grant-in-Aid No. 934053 from the Ministry of Education, Japan.     

Raman and infrared spectra of toxin gamma from the venom of the scorpion Tityus serrulatus

Toxin gamma is a basic, low-molecular-weight, neurotoxic protein, isolated from the venom of the Brazilian scorpion, Tityus serrulatus. Raman spectra (400-1800 cm-1 region) of this toxin in both the lyophilized state and in 0.1 M acetate buffer (pH 4.5) and the infrared spectrum (700-4000 cm-1 region) of a solid film were investigated. From the vibrational spectra, it can be concluded that the polypeptide backbone of toxin gamma consists of a mixture of the different secondary structures, with predominance of beta-sheet, followed by unordered structure and alpha-helix, with some evidence of beta-turn structures. The four disulfide bridges assume the gauche-gauche-gauche conformation of the CCSSCC fragments. The intensity ratio of the doublet at 853 and 828 cm-1 suggests that four out of the five tyrosine residues are exposed. The three tryptophan residues are exposed on the surface, and the single methionine residue assume the gauche-gauche conformation. Toxin gamma retains full activity in the pH 4.5-7.5 range, but is almost completely inactivated at pH 11.5.