Relationship between gibberellic acid and water amount in the cotton seed

The role of endogenous GA₃ and its application to seed development in two cotton genotypes Hybrid-6 (H-6) (big seeds) and Gujarat cotton 13 (G. Cot) (small seeds) was studied. Kernel and seed coat were subjected to growth analysis in terms of dry weight, water amount, and rates of dry matter accumulation and water uptake. H-6 kernel had manifold higher dry weight and water amount than G. Cot. Seed coat of both genotypes had similar dry weight at maturity, but the maximum rates of dry matter accumulation and water uptake were distinctly higher in H-6. According to growth analysis, development of seed kernel and coat was subdivided into four phases, i.e., cell division, cell elongation, dry matter accumulation and maturation. Endogenous GA₃ level was estimated in kernel and seed coat by indirect ELISA using antibodies raised against GA₃. GA₃ amount per seed components was higher in the seed kernel of H-6 than of G. Cot, except 33 and 36 days after anthesis in kernel. H-6 seed coat had the higher amount of GA₃ during cell division phase than that of G. Cot. Close correlation between in vivo GA₃ level and water amount was recorded in both seed components. With GA₃ or GA₃ + NAA treatments in ovule culture, higher promotion in dry weight, water amount and seed size was noted in G. Cot than in H-6 suggesting that G. Cot is more deficient in endogenous GA₃. The greatest stimulation of parameters studied was obtained in ovule culture with GA₃ + NAA. When GA₃ or GA₃ + NAA was applied, initial significant difference in water amount and seed size was nullified. Data presented in this study indicated that GA₃ regulates cell expansion through the water uptake by cotton seed.     

Fasciola hepatica: effect of 4-amino-6-trichloroethenyl-1,3-benzenedisulfonamide on glycolysis in vitro

In vitro, 4-amino-6-trichloroethenyl-1,3-benzenedisulfonamide, a potent fasciolicide, causes a potent concentration-dependent inhibition of glucose uptake by mature Fasciola hepatica. In F. hepatica treated with the disulfonamide and then fed [U-¹⁴C]glucose, there was a 60% inhibition of glucose utilization and a corresponding inhibition of acetate and propionate formation. Treated fluke parasites possessed much lower levels of adenosine triphosphate, phosphoenolpyruvate, glucose 6-phosphate, and fructose 6-phosphate than untreated parasites and contained higher levels of glycerol and the free sugars fructose and mannose. Direct measurement of the effect of the disulfonamide on the glycolytic enzymes of F. hepatica demonstrated that 3-phosphoglycerate kinase (EC 2.7.2.3) and phosphoglyceromutase (EC 2.7.5.3) were inhibited. It is therefore suggested that the fasciolicidal activity of 4-amino-6-trichloroethenyl-1, 3-benzenedisulfonamide is due to inhibition of the enzymes 3-phosphoglycerate kinase and phosphoglyceromutase which effectively blocks the Embden-Myerhof glycolytic pathway.     

Ludalbin,a new lactone from Artemisia ludoviciana

Artemisia ludoviciana Nutt. ssp. albula (Woot.) Keck, a member of the vulgaris complex, contains a sesquiterpene lactone, ludalbin, which is 8-α-acetoxydouglanine.     

Calmodulin and the target size of the (Ca2+ + Mg2+)-ATPase of human red-cell ghosts

An average target size of 251 kDa has been obtained for the (Ca²⁺ + Mg²⁺)-ATPase of calmodulin-depleted erythrocyte ghosts by radiation inactivation with 16 MeV electrons. This is close to twice the size of the purified calcium-pump polypeptide. When calmodulin was included during the ATPase assay, a component of about 1 MDa appeared in addition to the activated dimer.     

Phosphorylase activity in relation to starch synthesis in developing Hordeum distichum grain

Activity, control and primer requirements of starch phosphorylase in developing barley endosperm were investigated. Phosphorylase was detected in endosperm extracts from 3 days after anthesis. Unprimed activity was predominant between 2 and 10 days after anthesis, when it constituted 70–80% of total activity, but this proportion declined rapidly as the grain developed. The existence of at least 2 isoenzymes was indicated by studies of pH dependence and phosphate inhibition, and was further supported by acrylamide gel electrophoresis and column chromatography using DEAE-cellulose. The two isoenzymes which ere possibly both glyco proteins, appear in barley endosperm soon after anthesis. One appears capable of unprimed activity, and may be associated with the initiation of a-1,2 glucans, which then serve as primers for starch synthetase. This disappears by 13–15 days after anthesis. The other isoenzyme is capable of some unprimed activity but undergoes modification between 15 and 20 days after anthesis, resulting in the loss of unprimed activity. The relevance of the results to initiation of starch synthesis and to starch synthetase in amyloplasts is discussed.     

Indol-3yl-acetic acid in roots of Zea mays

Indol-3yl-acetic acid was identified in extracts of sterile roots of Zeamays seedlings by means of TLC, chromogenic reactions, GLC and GC-MS.     

The enzymatic sulphation of heparan sulphate by hen's uterus

A sulphotransferase preparation from hen's uterus catalysed the transfer of sulphate from adenosine 3′-phosphate 5′-sulphatophosphate to N-desulphated heparan sulphate, heparan sulphate, N-desulphated heparin and dermatan sulphate. Heparin, chondroitin sulphate and hyaluronic acid were inactive as substrates for the enzyme. N-desulphated heparin was a much poorer substrate for the enzyme than N-desulphated heparan sulphate suggesting that properties of the substrate other than available glucosaminyl residues influenced enzyme activity. N-acetylation of N-desulphated heparin and N-desulphated heparan sulphate reduced their sulphate acceptor properties so it was unlikely that the N-acetyl groups of heparan sulphate facilitated its sulphatiion. Direct evidence for the transfer of [³⁵S]sulphate to amino groups of N-desulphated haparan sulphate was obtained by subsequent isolation of glucosamine $\text{N-[}{}^{35}\text{S}\text{]}\text{sulphate}$ from heparan [³⁵S]sulphate product. This was made possible through the use of a flavobacterial enzyme preparation which contained “heparitinase” activity but had been essentially freed of sulphatases. Attempts to transfer [³⁵S]sulphate to glucosamine or N-acetylglucosamine were unsuccessfull.     

Membrane lipid composition and susceptibility to bile salt damage

Erythrocyte membranes with low sphingomyelin: choline-containing phospholipid ratios haemolyse at low concentrations of the bile salt, glycocholate. Erythrocytes with higher sphingomyelin: choline-containing phospholipid ratios require progessively greater concentrations of the bile salt for lysis.Sublytic concentrations of glycocholate remove phospholipid and acetylcholinesterase from the membranes. Membranes with low sphingomyelin: choline-containing phospholipid ratios lose both particulate (microvesicles of distinct composition) and ‘solubilized’ material, the particulate form predominating. The proportion of particulate material falls with increase of the membrane sphingomyelin: choline-containing phospholipid ratio and those membranes of highest sphingomyelin: choline-containing phospholipid ratio lose material predominantly in ‘solubilized’ form.Sheep erythrocytes treated to increase their content of phosphatidylcholine (and thereby reduce their membrane sphingomyelin: choline-containing phospholipid ratio) become more susceptible to lysis by glycocholate.These observations indicate a correlation between membrane lipid composition and the perturbation of membranes with bile salt; they also point to possible features of membranes capable of surviving exposure to the high bile salt concentrations of the biliary tract.