Sucrose-Modulated Morphogenesis in Anagallis arvensis L.

Sucrose was found to have a modulating effect on the morphogenesisof Anagallis arvensis L. leaves cultured in a Murashige-Skoogmedium. Root formation and growth seem to be more independentthan other morphogenetic expressions. Roots formed without exogenoussugars at 25°C but sucrose seemed to be necessary at 32and 35°C. Sucrose at 3% improved shoot formation at 25°Cand had an inhibitory effect at 6%concentration and 35°C.Shoot growth (internode length) is inhibited by sucrose concentrationshigher than 3%. Sucrose could also replace light irradiancein regulating shoot and leaf growth. A higher sucrose concentration,than that required for roots and shoots formation, is necessaryfor flower and fruit formation, but sucrose could not replacethe photoperiod requirement for flowering in culture medium. (Received June 17, 1985; Accepted December 24, 1985)     

Effect of some carbamate pesticides on nodulation,plant yield and nitrogen fixation byPisum sativum andVigna sinensis in the presence of their respective rhizobia

Summary Six carbamate pesticides namely 1-naphthol, sevin, dimetilan, trematan, NaDDC and dymid were studied to see their effect on nodulation and nitrogen fixation inPisum sativum andVigna sinensis. Low concentrations of the pesticides have little effect on nodulation and nitrogen fixation, whereas higher concentrations adversely effect these processes. The results also indicate that then sensitivity depends upon the species of the Rhizobium and also the type of the pesticide. Pesticides belonging to the carbamate group differ in their capacity to affect nodulation and nitroge fixation.     

Remobilization of labelled nitrogen from vegetative tissues to pods of mungbean

Summary Remobilization of¹⁵N from vegetative tissue of mungbean (Vigna radiata (L.) Wilczek) into pods was measured during the reproductive phase of growth. Plant tissue was labelled with¹⁵N during vegetative development. Experiments were conducted in the field at two sites. At one site the soil provided cowpeas with most of their N but at the other site N fixation provided most of the N. Remobilized N from vegetative tissue to pods occurred soon after they began to develop. The quantity of the labelled N ultimately remobilized to the pods amounted to 50% for one cultivar (Tx33) at the high soil N site and 70% at the low N site. For the other cultivar (Tx13) the values were 25% and 30%, respectively. The two cultivars performed very differently with respect to partitioning of N into pods and the rate of N fixation. Even though more N was accumulated in the shoots of the high N fixing cultivar (Tx13) less total N was contained in the pods.     

Enhancement of water status by calcium pretreatment in groundnut and cowpea plants subjected to moisture stress

Summary The effect of calcium in the water relations and tolerance to moisture deficits was tested in groundnut and cowpea. In both species, enrichment of tissue with calcium resulted in maintenance of a higher water status under stress associated with low proline accumulation. The extent of membrane damage (as reflected by the absorbance at 273 nm) was lesser in leaves of plants fed with higher levels of Ca⁺⁺ when subjected to simulated stress. The rate of water loss from the leaves of Ca⁺⁺-enriched plants was also lower. The possible role of Ca⁺⁺ in inducing membrane stability and maintenance of higher water status is discussed.     

Translucent Tissue Defects in Solanum tuberosum L. : II. Alterations in Lipolytic Acyl Hydrolase, Lipoxygenase, and Morphology of Mitochondria and Amyloplasts

We analyzed a physiological defect that involved translucent-like tissue which occurred randomly in potato tubers (Solanum tuberosum L., cv Kennebec) after 8 months of storage. The translucent areas had reduced lipoxygenase (0.73-fold) and lipolytic acyl hydrolase (0.27-fold) activities. The effect(s) of these reduced enzyme activities in vivo is uncertain, but they may have influenced composition, turnover and permeability of membranes because potato lipid is primarily membranous in nature. Electron micrographs of the translucent tissue revealed a discernible decrease in the number of starch granules compared to normal/healthy tissue. A few remaining amyloplasts, which still contained starch granules, possessed large electrondense areas (stroma) within the organelle. Mitochondria in translucent tissue appeared to be present in increased numbers, were aggregated, had fewer but swollen cristae, and, morphologically, were of irregular size and shape suggestive of division. The result of this tuber defect appeared, in part, to be an exaggerated or accelerated form of senescence.     

Differential Proteolysis of Glycinin and beta-Conglycinin Polypeptides during Soybean Germination and Seedling Growth

The degradation of the major seed storage globulins of the soybean (Glycine max [L.] Merrill) was examined during the first 12 days of germination and seedling growth. The appearance of glycinin and β-conglycinin degradation products was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cotyledon extracts followed by electroblotting to nitrocellulose and immunostaining using glycinin and β-conglycinin specific antibodies. The three subunits of β-conglycinin were preferentially metabolized. Of the three subunits of β-conglycinin, the larger α and α′ subunits are rapidly degraded, generating new β-conglycinin cross-reactive polypeptides of 51,200 molecular weight soon after imbibition of the seed. After 6 days of growth the β-subunit is also hydrolyzed. At least six polypeptides, ranging from 33,100 to 24,000 molecular weight, appear as apparent degradation products of β-conglycinin. The metabolism of the glycinin acidic chains begins early in growth. The glycinin acidic chains present at day 3 have already been altered from the native form in the ungerminated seed, as evidenced by their higher mobility in an alkaline-urea polyacrylamide gel electrophoresis system. However, no change in the molecular weight of these chains is detectable by sodium dodecyl sulfate-polyarylamide gel electrophoresis. Examination of the glycinin polypeptide amino-termini by dansylation suggests that this initial modification of the acidic chains involves limited proteolysis at the carboxyl-termini, deamidation, or both. After 3 days of growth the acidic chains are rapidly hydrolyzed to a smaller (21,900 molecular weight) form. The basic polypeptides of glycinin appear to be unaltered during the first 8 days of growth, but are rapidly degraded thereafter to unidentified products. All of the original glycinin basic chains have been destroyed by day 10 of growth.     

Beta-galactosidase in the seminal plasma and reproductive organs of the bull

The distribution of beta-galactosidase activity was studied in different reproductive organs, seminal plasma and spermatozoa of the bull. The highest specific activity of beta-galactosidase was found in testis and in different parts of the epididymis, where the activity seemed to be partly in secretory (cauda secretion) and partly in non-secretory, bound form (caput to cauda epididymidis). Gel filtration on Sepharose 6B at pH 7.0 revealed two beta-galactosidase forms (GF-1, Mr approximately 500,000-600,000 and GF-2, Mr approximately 190,000-220,000) in reproductive organs and seminal plasma. The pH-optimum of both beta-galactosidase forms was about 3.75-4.75. Hg2+ and p-chloromercuribenzoate inhibited strongly these activities. Further, form GF-2 seemed to be slightly more sensitive to the thermal inactivation at 50-70 degrees C than form GF-1. In chromatofocusing beta-galactosidase activities in bull seminal plasma coeluted with those of the cauda epididymidis (pI-values 7.5-6.4). On the contrary, prostate, Cowper's gland, testis, ampulla and seminal vesicles had enzyme activities eluting at lower pI-values (6.3-4.2). Thus, the seminal plasma activity is mainly an indicator for the function of the epididymal cauda.     

RNase H is not involved in the induction of stable DNA replication in Escherichia coli.

rnh mutations of Escherichia coli inactivating RNase H activity allow the initiation of rounds of DNA replication in the absence of protein synthesis (stable DNA replication). However, levels of RNase H did not change during or after the induction of stable DNA replication in rnh+ strains by incubation with nalidixic acid or UV irradiation.     

Selection, mapping, and characterization of osmoregulatory mutants of Escherichia coli blocked in the choline-glycine betaine pathway.

Osmotically stressed Escherichia coli cells synthesize the osmoprotectant glycine betaine by oxidation of choline through glycine betaine aldehyde (choline----glycine betaine aldehyde----glycine betaine; B. Landfald and A.R. Str?m, J. Bacteriol. 165:849-855, 1986. Mutants blocked at the level of choline dehydrogenase were isolated by selection of strains which did not grow at elevated osmotic strength in the presence of choline but grew when supplemented with glycine betaine. A gene governing the choline dehydrogenase activity was named betA. Mapping by P1 transduction, F' complementation, and deletion mutagenesis showed the betA gene to be located at 7.5 min in the argF-codAB region of the chromosome. Mutants carrying deletions of this region also lacked glycine betaine aldehyde dehydrogenase activity and high-affinity uptake activity for choline; these deletions did not influence the activities of glycine betaine uptake or low-affinity choline uptake, both of which were osmotically regulated.