Conformational states of sunflower (Helianthus annuus) Helianthinin: effect of heat and pH

The structure and solubility of helianthinin, the most abundant protein of sunflower seeds, was investigated as a function of pH and temperature. Dissociation of the 11S form (hexamer) into the 7S form (trimer) gradually increased with increasing pH from 5.8 to 9.0. High ionic strength (I = 250 mM) stabilizes the 11S form at pH > 7.0. Heating and low pH resulted in dissociation into the monomeric constituents (2-3S). Next, the 7S and 11S forms of helianthinin were isolated and shown to differ in their secondary and tertiary structure, and to have denaturation temperatures (T(d)) of 65 and 90 degrees C, respectively. Furthermore, the existence of two populations of the monomeric form of helianthinin with denaturation temperatures of 65 and 90 degrees C was described. This leads to the hypothesis that helianthinin can adopt two different conformational states: one with T(d) = 65 degrees C and a second with T(d) = 90 degrees C.     

Hysteroscopy as a diagnostic aid for uterine diseases of cattle]

A method for hysteroscopy in cattle, using a rigid tube for passage through the cervical canal, is described. Using this method, passage through the cervical canal is possible independent of the stage of the gynaecological cycles. The hysteroscopic findings of 105 examinations in cows are described and discussed.     

Multiplex PCR for the diagnostic detection of Coxiella burnetii in cow's milk

A multiplex PCR based assay was developed for the highly sensitive and specific detection of Coxiella (C.) burnetii in cow's milk. The assay simultaneously amplifies a diagnostic target within the C. burnetii IS1111 sequence and a control target within the bovine CD18 gene. The internal PCR amplification control allows the discrimination of false negative results (single tube reaction failures) from negative results due to true absence of target sequences. In order to maximize the sensitivity of the assay, a sample preparation method including a centrifugation step to concentrate the bacterium was developed. In milk samples artificially contaminated with serial dilutions of C. burnetii, about four particles per ml could reproducibly be detected. The sensitivities of both assays, multiplex PCR and PCR with only a single pair of primers ('simplex' PCR), were observed to be similar.     

木豆杂种优势利用研究进展

自1974年发现木豆雄性不育株以来,国际上不断对木豆核雄性不育(GMS)和核质互作雄性不育(CGMS)基因及其种质资源进行研究和挖掘,最终实现了木豆杂种优势的成功利用。本文系统总结了过去30多年来,国际上木豆杂种优势机理、表现及授粉方式等基础研究,GMS、CGMS不育系及其配套制种体系研究,杂种优势强度研究,以及木豆杂交种生产技术研究进展。提出了木豆杂种优势利用的具体研究方向和展望。