The preparation in vitro of chrysanthemum for transplantation to soil

Plantlets of Dendranthema grandiflora Pennine Reel were grown from nodal sections on Sorbarods saturated with liquid medium containing 0–3 mg 1^–1 of various growth retardants. After 4 weeks they were transferred to compost and maintained at a relative humidity of 42% at 27.5°C. Wilting was assessed over a period of 3 h. Plantlets treated with paclobutrazol, flurprimidol, triapenthenol, chlorphonium chloride, uniconazol and ancymidol showed dose-related reductions in wilting up to a concentration of 3 mg 1^–1. Responses to tetcyclacis and mepiquat chloride were weaker, and no responses to chlormequat chloride, BTS 44584 or diaminozide could be detected. These observations are compatible with an hypothesis that resistance to wilting derives from inhibited synthesis of gibberellins.     

Immunochemical characterisation of parathyroid hormone-related protein from tumor and non-tumor cells

The molecular forms of parathyroid hormone-related protein (PTHRP) in conditioned media from the BEN human lung cancer cell line, rat parathyroid cells (PT-r) and human keratinocytes were studied by gel-filtraton chromatography with assay of PTHRP by immunoassays and bioassay. Immunoreactivity (1–86 and 1–34) and bioactivity (1–34) in conditioned media eluted as a coincident major peak (approx. molecular mass 19–22 kDa) and there was evidence of amino-terminal species in the molecular mass range 10–16 kDa in BEN and keratinocyte media. Western blotting of PTHRP affinity purified by monoclonal antibodies directed at regions 1–34 or 37–67, identified a major species in all cell cytosols and media with an apparent molecular mass of 24–25 kDa, consistently slighty larger than recombinant PTHRP(1–141) (mobility of 21 kDa) which may represent an intact or native form of PTHRP. Additional amino-terminal species were identified in medium from keratinocytes (16 and 7 kDa), BEN cells (18 and 14 kDa) and PT-R cells (17 kDa), suggesting that processing occurs at the C-terminus and within the mid-region to form a range of amino-terminal fragments.     

The root-knot nematode resistance gene (Mi) in tomato: construction of a molecular linkage map and identification of dominant cDNA markers in resistant genotypes

A dominant allele at the Mi locus on chromosome 6 of tomato (Lycopersicon esculentum Mill) confers resistance to three species of root-knot nematodes (Meloidogyne). The resistance, which is associated with a localized necrotic response, was originally introduced into tomato from the wild species Lycopersicon peruvianum. As a step towards the molecular cloning of Mi, we have identified closely linked DNA markers from both cDNA and genomic DNA libraries as restriction fragment length polymorphisms (RFLPs). DNA from tomato populations segregating for nematode resistance was analyzed to generate a high-resolution genetic map of this region. Additional information on gene order was obtained by comparing the size of the introgressed L. peruvianum chromosomal segment within a collection of nematode-resistant tomato lines. Among the four cDNA markers that are tightly linked to Mi, three are dominant, i.e. L. peruvianum-specific. One cDNA marker corresponds to a gene family comprising 20-30 members, one of which is diagnostic for all nematode-resistant genotypes tested. The presence of non-homologous sequences around the Mi gene may contribute to the suppression of recombination in this region of the genome in crosses heterozygous for Mi. The potential of 'walking' from closely linked markers to Mi is discussed.     

心房钠泵因子对颈动脉窦压力感受器反射的易化作用

Effects of atriopeptin II (APII) on the carotid sinus baroreflex in anesthetized rats and on the sinus nerve afferent activity in the anesthetized rabbits were investigated. The results were as follows: (1) By perfusing the isolated left carotid sinus with APII (1 microgram/ml) in anesthetized rats (n = 10), the threshold pressure (TP) of the carotid baroreflex did not show any change, while the equilibrium pressure (EP), the saturation pressure (SP) and the operating range (OR) were decreased from 101 +/- 2.8 to 95 +/- 2.0 mmHg (P less than 0.05), 202 +/- 5.2 to 168 +/- 6.1 mmHg (P less than 0.001) and 128 +/- 5.5 to 93 +/- 6.3 mmHg (P less than 0.001), respectively. The function curve of the baroreflex was shifted to the left and downward with a peak slope (PS) increased during perfusing with APII. In contrast, by perfusing the carotid sinus with sodium nitroprusside (NP, 0.5 micrograms/ml), TP and EP remained unchanged, whereas SP and OR were increased from 188 +/- 6.4 to 218 +/- 6.0 mmHg (n = 6, P less than 0.01) and from 107 +/- 6.9 to 132 +/- 7.6 mmHg (P less than 0.05), respectively. The function curve of the baroreflex and its PS were not affected by NP. The sinus nerve afferent activity was quite stable with the perfusion of carotid sinus at constant intrasinus pressure (ISP) in the rabbits (n = 6) and increased during the elevation of ISP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence for age-related changes in pyridine nucleotide content of isolated rat islets

The purpose of this study was to document the effect of age on alpha-glycerophosphate activity and pyridine nucleotide concentration in pancreatic islets isolated from rats. In order to do this, islets were isolated from pancreases of 2 and 12 month-old rats, and measurements made of alpha-glycerophosphate activity and of NAD+ and NADH, determinations were made following incubation at both basal (5.6 mM) and elevated glucose concentrations (28 mM). The results indicated that islet alpha-glycerophosphate dehydrogenase activity was decreased (P less than 0.001) by approximately 50% in the older rats. This was associated with an increase in mean (+/- SEM) basal NADH content (pmol/microgram DNA) in 12 month-old (4.48 +/- 0.31) as compared to 2 month-old rats (2.73 +/- 0.49). Although mean (+/- SEM) basal NAD+ levels (pmol/microgram DNA) were the same in 2 and 12 month-old rats (29.4 +/- 2.5 and 30.8 +/- 2.8, respectively), NAD+ content following incubation at elevated levels of glucose declined (absolutely and relatively) to a significantly greater degree in the younger rats. The incremental rise in islet NADH concentration following incubation at the elevated glucose concentration was similar in the two groups, but the relative increase was only approximately half as great in islets from 12 month-old rats. These data indicate that the age-related decline in the activity of alpha-glycerophosphate dehydrogenase, the enzyme regulating the glycerophosphate shuttle system in 12 month-old rats, is associated with alterations in islet pyridine nucleotide composition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Insulin induces activation and translocation of protein kinase FA (a multifunctional protein phosphatase activator) in human platelet

Protein kinase FA (an activator of the ATP.Mg-dependent multifunctional protein phosphatase) has been identified in both cytosol and plasma membrane isolated from human platelets. The FA activity in the cytosol is active whereas the FA activity in the membrane is inactive. Quantitative analysis further indicates that approximately 90% of total FA is present in the membrane whereas only 10% of FA is localized in the cytosol, suggesting that the inactive membrane-associated FA might be regulated. This notion has subsequently been demonstrated that exposure of platelets to physiological concentrations of insulin for only 1 min resulted in an increase in cytosolic FA activity to about 300% of control values in the absence of insulin and in a corresponding decrease in FA activity in the membrane. It is concluded that the molecular basis for insulin action on cellular metabolism may partly be mediated through the activation and translocation of protein kinase FA in the membrane. It is suggested that redistribution of protein kinase FA may represent a transmembrane signal of insulin.