Terpenoids and Their Possible Role in Defense Against a Fungal Pathogen Alternaria tenuissima in Chrysanthemum morifolium Cultivars

Journal of Plant Growth Regulation - Terpenoids are a class of structurally diverse natural products involved in various plant biological processes. Their primary function is believed to provide...     

Involvement of the fastigial nuclei in vagally mediated respiratory responses

Xu, Fadi, and Donald T. Frazier. Involvement of thefastigial nuclei in vagally mediated respiratory responses.J. Appl. Physiol. 82(6):1853-1861, 1997.Previous studies have demonstrated that thecerebellum, especially the fastigial nucleus (FN), is capable ofmodulating respiratory responses to chemical and mechanical stimuli.Because there is evidence to show projections from vagal afferents tothe FN, the goal of this study was to determine the role of the FN inthe respiratory reflexes elicited by activation of vagal afferents.Experiments were performed in anesthetized (chloralose), paralyzed, andartificially ventilated cats with an occipital exposure of thecerebellum. Administration of capsaicin (Cap; 5-10 µg/kg) viathe right external jugular vein at the end of inspiration andapplication of lung inflation (LI; 10 cmH₂O) during inspiration werecarried out to stimulate nonmyelinated and myelinated vagal afferents,respectively. The phrenic neurogram was recorded as anindex of the respiratory motor output. Control cardiorespiratoryvariables [expiratory duration(TE), arterial bloodpressure] and their immediate responses to stimuli were comparedbefore and after bilateral lesions of the FN. The results showed thefollowing. 1) Capinjection and LI resulted in a dramatic increase inTE (apnea).2) FN lesions did not significantlyalter the control TE; however,the apneic duration induced by Cap injection was prolonged.3) Neither FN lesions norcerebellectomy affected the apneic duration that resulted fromapplication of LI. 4) Cold blockadeof the vagi (6-8°C) eliminated the respiratory responses elicited by LI but not Cap injection; vagotomy abolished the responses to both stimuli. 5) FN lesions didnot change the control ABP or its responses to either LI or Capinjection. It is concluded that the FN is involved in vagally mediatedrespiratory reflexes elicited by activation of nonmyelinated (C-fiber)vagal afferents.

     

Subject-specific,whole-body models of the stooped posture with a personal weight transfer device

A prior laboratory study found that when wearing a weight transfer device in the stooped posture, trunk flexions were reduced, and subjects who did not experience flexion–relaxation of the erector spinae had reduced back muscle activity. Whole-body musculoskeletal models, which included individual passive torso stiffness and anthropometry, were implemented to predict loads in the passive tissues of the back and the leg joints. Results predicted that when wearing the device in the stooped posture, compression and shear forces at the L5–S1 level were reduced by 13% and 12% respectively. Internal loads in the leg joints were reduced between 10% and 31%. Much of the reduction in joint loads may be a result of the device’s ability to limit torso flexion during stoop, rather than a transferring of load. While these results show possible benefit in the short-term, further study is needed on the long-term effects to determine if the device is an effective intervention for those who use the stooped posture routinely.     

Genetic Mapping of Quantitative Trait Loci Underlying Flowering Time in Chrysanthemum (Chrysanthemum morifolium)

Flowering time is an important trait in chrysanthemum, but its genetic basis remains poorly understood. An intra-specific mapping population bred from the cross between the autumn-flowering cultivar ‘Yuhualuoying’ and the summer-flowering ‘Aoyunhanxiao’ was used to determine the number and relative effect of QTL segregating for five measures of flowering time. From flowering time data recorded over two consecutive seasons, 35 additive QTL were detected, each explaining between 5.8% and 22.7% of the overall phenotypic variance. Of these, 13 were detected in both years. Nine genomic regions harboring QTL for at least two of the five traits were identified. Ten pairs of loci epistatically determined the flowering time, but their contribution to the overall phenotypic variance was less than for the additive QTL. The results suggest that flowering time in chrysanthemum is principally governed by main effect QTL but that epistasis also contributes to the genetic architecture of the trait, and the major QTL identified herein are useful in our ongoing efforts to streamline the improvement of chrysanthemum via the use of molecular methodology.     

Variation for Resistance to <i>Alternaria tenuissima</i> and Potential Structural Mechanism among Different Cultivars of <i>Chrysanthemum morifolium</i>

Black spot disease, caused by the necrotrophic fungus Alternaria tenuissima (Fr.) Wiltsh (A. tenuissima), is considered a highly destructive disease of Chrysanthemum (Chrysanthemum morifolium Ramat.). A set of 17 accessions of commercial chrysanthemum cultivars were evaluated for resistance to A. tenuissima by seedling artificial inoculation. It was found that the reaction of the accessions to artificial inoculation ranged from resistant to highly susceptible. Five varieties of chrysanthemum (‘Zhongshan Taogui’, ‘Jinba’, ‘Zhongshan Jinguan’, ‘Jinling Wanhuang’ and ‘Jinling Yangguang’) were resistant; two varieties of chrysanthemum (‘Zhongshan Xinggui’ and ‘Zhongshan Jinkui’) were moderately resistant; and others were susceptible to various degrees, four varieties of chrysanthemum (‘Zhongshan Zihe’, ‘Zhongshan Jiuhong’, ‘Zaoyihong’ and ‘Jinling Jiaohuang’) were highly susceptible, especially. Some leaf morphological features of two resistant and two highly susceptible cultivars were further researched. Trichome density, length, height, gland size and stomata density were found to be associated with plant passive resistance. Resistant varieties that were identified in present study will be promising germplasm for exploitation of breeding programmes aimed at developing A. tenuissima-resistant cultivars and increasing genetic diversity.     

Hexagonal-String Phases in Suspension Flow

Abstract

Investigations of the structure of flowing colloidal suspensions have seen structures of predominantly hexagonal strings moving in layered arrangements in the direction of the velocity gradient. A combination of computer simulation trajectories and computer graphics show that the predominant “hexagonal string phase” is the BCC lattice sheared along its (111) slip plane and, moreover, that all the common cubic lattice types contain “hexagonal strings”.