Power and control muscles of cicada song: structural and contractile heterogeneity

Sound production in cicadas is powered by a pair of large muscles whose contractions cause buckling of cuticular tymbals and thereby create sound pulses. Sound is modulated by control muscles that alter the stiffness of the tymbals or change the shape of the abdominal resonance chamber. Muscle ultrastructure and contractile properties were characterized for the tymbal muscle and two control muscles, the ventral longitudinal muscle and the tymbal tensor, of the periodical cicada Magicicada septendecim. The tymbal muscle is a fast muscle that is innervated by a single motoraxon. The control muscles are an order of magnitude less massive than the tymbal muscles, but their innervation patterns were considerably more complex. The tensor muscle is innervated by two axons, each of which evokes rather slow twitches, and the ventral muscle is innervated by at least six axons, some of which produce fast and the others slow contractions. Muscle contraction kinetics correlated well with ultrastructure. Fibers of the tymbal muscle and the portions of the ventral muscle thought to be fast were richly supplied with transverse tubules (T-tubules) and sarcoplasmic reticulum (SR); slow portions of the ventral muscle and the tensor muscle had relatively little SR.Abbreviations SR sarcoplasmic reticulum - TTS transverse tubular system - VLM ventral longitudinal muscle     

Infraciliature and myoneme system of Campanella umbellaria (Protozoa, Ciliophora, Peritrichida)

The infraciliature and myoneme system of Campanella umbellaria were revealed using the protargol impregnation technique. The main characteristics of the infraciliature are the peristomial ciliary rows (haplokinety and polykineties), which make four and a half turns around the peristomial disc before plunging into the infundibulum, and the aboral infraciliature, which is made up of the aboral ciliary wreath (trochal band) and the scopula. The myoneme system is composed of: 1) longitudinal fibers, which include 60-84 (mean 72.3) short longitudinal fibers, 40-56 (mean 45.8) medium-length longitudinal fibers, and numerous long longitudinal fibers; and 2) circular fibers, which include 8-12 (mean 9.3) peristomial ring fibers, linking fibers, support fibers, and peristomial disc fibers. The various fibers in C. umbellaria are interconnected to form a single myoneme system that may act as a cell skeleton as well as providing the mechanism by which the zooid contracts and relaxes.     

正常妊娠大鼠的Th2型免疫反应

采用流式细胞仪,^3H-TdR掺入和酶联免疫打点(enzyme-linked immunospot,ELISPOT)方法研究妊娠免疫学指标的改变。妊娠晚期大鼠脾脏单个核细胞表面分子主要组织相容性抗原Ⅱ(MHCⅡ)明显下调,外周血单个核细胞表达CD11c明显减少,共激活分子B7-1和B7-2未见改变;脾脏和外周血单个核细胞中Th2细胞因子IL-10、IL-4表达增多,TGFD阳性细胞数也明显增加,而Th1细胞因子IFNγ的产生未受抑制。此外,脾脏和外周血中单个核细胞的抗原特异性增殖未见改变,而腹腔淋巴结细胞的增殖明显升高。脾脏单个核细胞在妊娠晚期分泌较少的抗原特异性抗体。提示妊娠期性激素具有免疫调节作用,可能与怀孕时Th1细胞介导的自身免疫性疾病得到缓解有关。     

Effects of grazing disturbance on the reproduction of a perennial herb, Cypella herbertii (Lindl.) Herb. (Iridaceae)

A recent study in a natural grassland in Argentina revealed that grazing strongly reduced the available pollinators for a population of Cypella herbertii. Comparing grazed and fenced areas (exclosures) we tested the hypothesis that self-incompatibility would be selected against in a pollinator-poor environment leading to changes in breeding system. No differences in breeding system were found between populations from inside and outside exclosures. However, we detected: (i) C. herbertii clearly exhibits a mixed-mating system but has a remarkably low spontaneous fruit formation; (ii) this species though highly self-compatible expresses a significant decay at seed set stage when self-pollinated. We conclude that grazing impact on pollinators together with C. herbertiis high dependence on pollinators should be considered when assessing the risk of extinction of this species.     

High-resolution magnetic resonance spectroscopy of the mouse vomeronasal organ

The chemical composition of the vomeronasal organ (VNO) was investigated by means of in vitro proton magnetic resonance spectroscopy (MRS) in prepubertal and adult mice of both sexes. Results demonstrate that MRS detects several chemical constituents in the VNO, showing their age- and sex-associated changes in concentration. Preliminary experiments also suggest the ability of MRS to show compositional changes in the VNO after pheromonal stimulation. MRS can serve as a useful technique to investigate vomeronasal chemoreception.     

Effect of light on the organogenic ability of garlic roots using a one-step in vitro system

A simple and efficient garlic in vitro shoot regeneration protocol has been developed. This system uses axenic root tips cultivated from the beginning in the presence of light and does not require any change or refreshing of the original medium during the entire process. The application of light from the beginning of the culture process did not affect the callus formation rate but did significantly improve the explant regeneration ability. In a 2-month period it was possible to obtain up to 250 shoots per gram of callus.Abbreviations BAP: 6-Benzylaminopurine - 2,4-D: 2,4-Dichlorophenoxyacetic acid - NAA: -Naphthaleneacetic acid Communicated by L. Peña     

Plant two-component systems: principles,functions, complexity and cross talk

Two-component systems have emerged as important sensing/response mechanisms in higher plants. They are composed of hybrid histidine kinases, histidine-containing phosphotransfer domain proteins and response regulators that are biochemically linked by His-to-Asp phosphorelay. In plants two-component systems play a major role in cytokinin perception and signalling and contribute to ethylene signal transduction and osmosensing. Furthermore, developmental processes like megagametogenesis in Arabidopsis thaliana and flowering promotion in rice (Oryza sativa) involve elements of two-component systems. Two-component-like elements also function as components of the Arabidopsis circadian clock. Because of the molecular mode of signalling, plant two-component systems also appear to serve as intensive cross talk and signal integration machinery. In this review we summarize the present knowledge about the principles and functions of two-component systems in higher plants and address several critical points with respect to cross talk, signal integration and specificity.Abbreviations AHK Arabidopsis histidine kinase - AHP Arabidopsis histidine-containing phosphotransfer domain protein - APRR Arabidopsis pseudo response regulator - ARR Arabidopsis response regulator - CCT CONSTANS CONSTANS-like TOC1 - CKI Cytokinin insensitive - CRE Cytokinin response - CTR Constitutive triple response - Ehd Early heading date - EIN Ethylene insensitive - ERS Ethylene response sensor - ETR Ethylene resistant - GARP-motif Found in Golden2 of maize, Arabidopsis B-type response regulators and Chlamydomonas Psr1 - HPt Histidine-containing phosphotransfer domain - NLS Nuclear localization signal - phyB Phytochrome B - TCS Two-component signalling - TOC Timing of CAB (chlorophyll a/b-binding protein) expression - WOL Wooden leg