Characterization of proteins associated with self-incompatibility in Solanum tuberosum

Summary The gametophytic self-incompatibility system of Solarium tuberosum is controlled by a single locus, designated as the S-locus. Protein extracts from potato styles of defined S-genotypes have been analysed by two-dimensional gel electrophoresis, and found to contain a group of basic glycoproteins. Each genetically determined allele S ₁ to S ₄ was associated with the presence of one of a number of these polypeptides differing slightly in isoelectric points (in the range 8.3–>9.1) and/or apparent molecular weight (ranging from 23,000 to 29,000). Two abundant basic polypeptides, one of which is apparently not glycosylated, were present in all genotypes examined. Amino-terminal protein sequence determinations revealed homologies of the S. tuberosum stylar proteins S₂, S₃ and S₄ with SI-associated polypeptides from Nicotiana alata and Lycopersicon peruvianum. With an oligonucleotide generated to the potato-S₂ N-terminal protein sequence, it was possible to detect a style-specific RNA species of 920 nucleotides. The oligonucleotide also behaved as an allele-specific probe when hybridized to total RNA of different S-genotypes.     

Cerebellar neurones: Differentiation and modulation of sensitivity to excitotoxic treatment

The neurite outgrowth and adhesion complex (NOAC), isolated from rabbit sera has been dissociated in its major components by reverse-phase chromatography in HPLC by using a C₁₈ column. SDS-PAGE analisys of the active fractions revealed the presence of three major bands of approximately 100, 70 and 50 kDa. Studies on the biological activity of NOAC were carried out on rat cerebellar granule cells. NOAC-cultured cells exhibit a marked resistance to excitotoxic stimuli carried by glutamate.     

Distribution of the molossinus allele of Sry, the testis-determining gene, in wild mice

When the Y chromosome of the laboratory inbred mouse strain C57BL/6 (B6) is replaced by the Y of certain strains of Mus musculus domesticus, testis determination fails and all XY fetuses develop either as hermaphrodites or XY females (XY sex reversal). This suggests the presence of at least two alleles of Sry, the male-determining gene on the Y:M. m. domesticus and B6. The B6 Y chromosome is derived from the Japanese house mouse, M. m. molossinus and therefore carries a molossinus Sry allele. As a first step to determine how the molossinus Sry allele evolved, its distribution pattern was determined in wild mice. The cumulative data of 96 M. musculus samples obtained from 58 geographical locations in Europe, North Africa, and Asia show the molossinus Sry allele is restricted to Japan and the neighboring Asian mainland and confirm that Japanese M. m. molossinus mice were derived in part from a race of M. m. musculus from Korea or Manchuria. Sry polymorphisms, as illustrated by the molossinus Sry allele, can serve as molecular markers for studies on the evolution of wild M. musculus populations and can help determine the role sex determination plays in speciation.      

Overexpression of phosphoenolpyruvate carboxylase from Corynebacterium glutamicum lowers the CO2 compensation point (*) and enhances dark and light respiration in transgenic potato

The effect of decreased or increased phosphoenolpyruvate carboxylase (PEPC) activity on the CO2 compensation point, respiration in the light or dark as well as the partitioning of carbon into starch, soluble sugars, organic acids, and amino acids was investigated using transgenic potato plants. Engineered PEPC activity ranged form 0.5-fold wild-type level in antisense plants to 5-fold wild-type levels in lines overexpressing the ccpc gene of Corynebacterium glutamicum encoding for a PEPC not modulated by protein phosphorylation. The CO2 compensation point determined according to Brooks and Farquhar (1985) was lower in PEPC overexpressors (32 l l^-1 CO2) compared to control potato lines (38 l l^-1 CO2), but was increased in antisense PEPC plants (42 l^-1 CO2). 3-fold overexpression of PEPC gave a minimum CO2 compensation point of 32 l l^-1 CO2. Increased PEPC activity resulted in enhanced respiration in the light and dark. Altered PEPC activity had no effect on the pattern of ¹⁴CO2 incorporation into leaf discs in the light. ¹⁴C pulse-chase experiments in the dark, demonstrated that substantially more total label was lost in the leaf discs from PEPC overexpressors. Metabolite levels were determined in 21 PEPC overexpressing lines after 8 h in the light. A 5-fold increase in PEPC over the wild-type increased malate (61%), starch (75%) and significantly increased sucrose contents 9150%). Total amino acid contents were only marginally increased. From gas exchange characteristics and labeling experiments it was concluded that PEP carboxylation, followed by an increased rate of respiratory CO2 release, might work as a HCO3^-/CO2 pump. This might result in elevated CO2/O2 ratios in the mesophyll, concomitant with a more favoured carboxylation/oxygenation ratio of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco).     

Development of an optimized interaction-mating protocol for large-scale yeast two-hybrid analyses

Background  

Protein-protein interactions have decisive roles in almost all aspects of the structural and functional organization of cells. But in spite of the increasing amount of complete genome sequence data, the ability to predict protein function from sequences alone is limited. Therefore comprehensive analysis of protein-protein interactions, as derived from the yeast two-hybrid mating system, will yield valuable information for functional biology on a proteomic scale.     

Characterization of 13 newly isolated strains of anaerobic, cellulolytic, thermophilic bacteria

Characteristics of 13 newly isolated thermophilic, anaerobic, and cellulolytic strains were compared with previously described strains of Clostridium thermocellum: ATCC 27405 and JW20 (ATCC 31549). Colony morphology, antibiotic sensitivity, fermentation end-products, and cellulose degradation were documented. All 13 strains were sensitive to erythromycin (5 μg/ml) and chloramphenicol (25 μg/ml), and all strains but one were sensitive to kanamycin (20 μg/ml). Polymerase chain reaction (PCR) amplification using primers based on gene sequences from C. thermocellum ATCC 27405 was successful for all 13 strains in the case of the hydrogenase gene and 11 strains in the case of phosphotransacetylase/acetate kinase genes. Ten strains amplified a product of the expected size with primers developed to be specific for C. thermocellum 16SrRNA primers. Two of the 13 strains did not amplify any product with the PCR primers designed for the phosphotransacetylase/acetate kinase and 16SrRNA primers. A MboI-like GATC- recognizing restriction activity was present in all of the five strains examined. The results of this study have several positive implications with respect to future development of a transformation system for cellulolytic thermophiles. Journal of Industrial Microbiology & Biotechnology (2001) 27, 275–280. Received 12 September 2000/ Accepted in revised form 20 November 2000     

Animal models of fibromyalgia

Animal models of disease states are valuable tools for developing new treatments and investigating underlying mechanisms. They should mimic the symptoms and pathology of the disease and importantly be predictive of effective treatments. Fibromyalgia is characterized by chronic widespread pain with associated co-morbid symptoms that include fatigue, depression, anxiety and sleep dysfunction. In this review, we present different animal models that mimic the signs and symptoms of fibromyalgia. These models are induced by a wide variety of methods that include repeated muscle insults, depletion of biogenic amines, and stress. All potential models produce widespread and long-lasting hyperalgesia without overt peripheral tissue damage and thus mimic the clinical presentation of fibromyalgia. We describe the methods for induction of the model, pathophysiological mechanisms for each model, and treatment profiles.     

土壤低剂量芘污染对蚯蚓若干生化指标的影响

通过人工污染土壤的方法,设计芘的暴露浓度为0、60、120、240、480、960μg.kg-1.暴露实验进行1、3、7和14d后,分别检测蚯蚓内脏中细胞色素P450含量、谷胱甘肽转移酶(GST)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量.结果表明,在供试浓度范围内,蚯蚓内脏中各生化指标对污染物暴露指示的敏感性存在差异:其中P450含量、GST和SOD活性最为敏感;POD和CAT活性次之;而MDA含量未对低剂量的芘暴露起到明显的指示作用.研究同时发现,低剂量污染物暴露的时间效应要强于剂量效应的影响.因而,在进行生态毒性诊断时,采用多指标和多时段的检测对增强指示的灵敏性和有效性尤为重要.