Site of bicarbonate effect in Hill reaction. Evidence from the use of artificial electron acceptors and donors

Using artificial electron donors and acceptors, it is shown here that the major HCO₃^? effect in the Hill reaction is after the “primary” electron acceptor (Q) of Photosystem II and before the site of action of 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (at the plastoquinone pool). Chloroplasts in the presence of both 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea, which blocks electron flow from the reduced primary acceptor Q^? to the plastoquinone pool, and silicomolybdate, which accepts electrons from Q^?, show no significant bicarbonate stimulation of electron flow. However, a 6–7-fold stimulation is clearly observed when oxidized diaminodurene, as an electron acceptor, and dibromothymoquinone, as an inhibitor of electron flow beyond the plastoquinone pool, are used. In the same chloroplast preparation no measurable effect of bicarbonate is observed in a Photosystem I reaction as monitored by electron flow from reduced diaminodurene to methyl viologen in the presence of 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea. The insensitivity of the bicarbonate effect to uncouplers of photophosphorylation and the dependence of this effect on the presence of a weak acid anion and on external pH are also reported.     

The distribution of the group specific component (Gc) in four endogamous groups of Punjab, North India

The paper reports the distribution of group specific component (Gc) types among four endogamous groups of Punjab: Jat Sikh, Khatri, Ramgarhia, and Ramdasia. A total of 418 individuals were tested for this polymorphism. The frequency of Gc1 alleles ranges between 0.7056 and 0.7636. These frequencies are compared with those obtained in other Indian populations.     

Modulatory effects of metanil yellow on immunity in rodents.

Pathomorphological and immunological studies were carried out on rodents following oral administration of 0, 0.1, 0.25 and 0.5% (w/w) metanil yellow, mixed in diet, for 30 days. No significant change in hematologic parameters and histologic architecture of liver, kidney, mesenteric lymph node, thymus and urinary bladder was observed except for mild desquamation of intestinal villi and moderate changes in Peyer's patches of small intestine with higher doses. Among immunological parameters, significant enhancement in the primary humoral immune response (anti-SRBC IgM plaque forming cells of spleen) was observed with the lowest dose of metanil yellow while higher doses produced opposing effects. An elevated cutaneous delayed type hypersensitivity (DTH) reaction to SRBC was seen in 0.1% metanil yellow treated animals but higher doses did not influence the reaction. The treatment also caused changes in functional capabilities of macrophages. Although these immune alterations could hardly influence the local immunity of gut, as measured by the capacity of animals to cause rejection of Nippostrongylus brasiliensis parasite, the potential to modulate the immunity in general by metanil yellow however assumes considerable biological significance.     

Interaction of benzanthrone with cytochrome P450: altered patterns of hepatic xenobiotic metabolism in rats

Benzanthrone, an anthraquinone dye intermediate, is commonly used for the synthesis of a number of polycyclic vat and disperse dyes. Our prior studies have shown that benzanthrone can be metabolized by rat hepatic microsomal cytochrome P450 (P450) (Biochem. Int., 18, 1989, 1237). In this study, the interaction of benzanthrone with rat hepatic microsomal P-450 and its effect on xenobiotic metabolism have been investigated. Parenteral administration of benzanthrone (40 mg/kg body weight) for 3, 7, or 21 days caused no change in the relative body weight or organ weight of rats. The levels of P450 were found to be reduced (33%-50%) in all the benzanthrone-exposed animals at all the time periods. In vitro addition of benzanthrone caused a spectral change with oxidized P450 and concentration-dependent reduction in the carbon monoxide spectrum of dithionite-reduced P450. The addition of benzanthrone to hepatic microsomes prepared from phenobarbital-treated rats resulted in spectral changes characterized by an absorbance maximum at 397 nm indicative of type I binding. In vitro addition of benzanthrone showed a concentration-dependent inhibition of hepatic aminopyrine N-demethylase (APD) and ethoxyresorufin-O-deethylase (ERD) activities with respective I50 values of 9.5 x 10(-4) and 8.0 x 10(-5) M. However, the inhibition of aryl hydrocarbon hydroxylase (AHH) even at the highest concentration of benzanthrone (10(-2) M), was of the order of only 29%. In vivo administration of benzanthrone also led to the inhibition of APD, AHH, and ERD activities at all treatment times although the magnitude of inhibition was of a lower order.(ABSTRACT TRUNCATED AT 250 WORDS)     

Histology and seasonal changes in the testes of a hill-stream fish Schizothorax plagiostomus.

Histology and annual cyclic changes in the testicular activity of S. plagiostomus have been described. The reproductive cycle has been divided into eight phases. The weight and volume of the testes and GSI show correlation with each other, and increase twice in a year (September and March), indicating the existence of two spawning periods. A distinct dormant period during winter intervenes the spawning peaks. Although the testes contain mature spermatozoa during winter, spermiation remains halted until last week of February. On the return of favourable environmental conditions in March, spermiation begins again and complete depletion takes place.     

Effect of chronic intake of ethanol on lactate/pyruvate and beta-hydroxybutyrate/acetoacetate ratios in rat liver.

Adult male rats were fed a liquid diet providing 35% of the calories as ethanol, while pair-fed controls received the corresponding diet with alcohol replaced by an equicaloric concentration of sucrose. After 1 month, lactate/pyruvate (L/P) and beta-hydroxybutyrate/acetoacetate (beta-HB/AcAc) ratios in the livers were determined under five different conditions: (1) both diets present up to the time of sacrifice, (2) ethanol diet replaced by control diet for 24 h before sacrifice, (3) ethanol diet replaced by control diet for 48 h before sacrifice, (4) as in the preceding, followed by intraperitoneal (i.p.) injection of ethanol, 1 g/kg, 1 h before sacrifice, (5) as in the preceding, but i.p. injection 3 h before sacrifice. The L/P ratio was significantly higher in the alcohol group than in controls under the first experimental condition, but the groups did not differ under the other four conditions. The beta-HB/AcAc ratio was also significantly higher in the alcohol group under the first condition. This difference disappeared in the second and third conditions. Under the fourth and fifth conditions the beta-HB/AcAc ratio was significantly higher in the controls. The results are compatible with an adaptive increase in mitochondrial reoxidation of NADH in the chronic alcohol groups, but the possibility of a change due to alcohol withdrawal can not be excluded.     

Effect of streptozotocin on the blood glucose level and histology of the principal islets of Channa punctatus (Bloch).

The effect of streptozotocin, an antibiotic and diabetogenic drug, has been studied on the blood glucose level and islet histology of a freshwater fish, Channa punctatus. The drug elicits a triphasic response in the blood glucose level, comprising an initial hyperglycemia followed by a transient fall, and restitution of normal values 3...4 days after the treatment. Significant degenerative changes occur in the islet beta cells. Severity of the beta cell damage is dose dependent and the drug has been found to be beta-cytotoxic to a considerable extent. Unlike mammals, Channa punctatus does not become diabetic following the streptozotocin administration, at doses varying 200-400 mg/kg b.wqnd over a period of 96 hours post-injection.     

A Novel Folate-Targeted Nanoliposomal System of Doxorubicin for Cancer Targeting

Targeted drug delivery systems for cancer improves anti-tumor efficacy and reduces systemic toxicity by restricting availability of cytotoxic drugs within tumors. Targeting moieties, such as natural ligands (folic acid, transferrin, and biotin) which are overexpressed on tumors, have been used to enhance liposome-encapsulated drug accumulation within tumors and resulted in better control. In this report, we explored the scope of targeting ligand folic acid, which is incorporated in liposome systems using folic acid-modified cholesterol (CPF), enabled highly selective tumor-targeted delivery of liposome-encapsulated doxorubicin and resulted in increased cytotoxicity within tumors. Folate-tagged poloxamer-coated liposomes (FDL) were found to have significantly higher cellular uptake than conventional poloxamer-coated liposomes (DL), as confirmed by fluorometric analysis in B16F10 melanoma cells. Biodistribution study of the radiolabeled liposomal system indicated the significantly higher tumor uptake of FDL as compared to DL. Anti-tumor activity of FDL against murine B16F10 melanoma tumor-bearing mice revealed that FDL inhibited tumor growth more efficiently than the DL. Taken together, the results demonstrated the significant potential of the folate-conjugated nanoliposomal system for drug delivery to tumors.     

Golden bananas in the field: elevated fruit pro‐vitamin A from the expression of a single banana transgene

Vitamin A deficiency remains one of the world's major public health problems despite food fortification and supplements strategies. Biofortification of staple crops with enhanced levels of pro‐vitamin A (PVA) offers a sustainable alternative strategy to both food fortification and supplementation. As a proof of concept, PVA‐biofortified transgenic Cavendish bananas were generated and field trialed in Australia with the aim of achieving a target level of 20 μg/g of dry weight (dw) β‐carotene equivalent (β‐CE) in the fruit. Expression of a Fe'i banana‐derived phytoene synthase 2a (MtPsy2a) gene resulted in the generation of lines with PVA levels exceeding the target level with one line reaching 55 μg/g dw β‐CE . Expression of the maize phytoene synthase 1 (ZmPsy1) gene, used to develop ‘Golden Rice 2’, also resulted in increased fruit PVA levels although many lines displayed undesirable phenotypes. Constitutive expression of either transgene with the maize polyubiquitin promoter increased PVA accumulation from the earliest stage of fruit development. In contrast, PVA accumulation was restricted to the late stages of fruit development when either the banana 1‐aminocyclopropane‐1‐carboxylate oxidase or the expansin 1 promoters were used to drive the same transgenes. Wild‐type plants with the longest fruit development time had also the highest fruit PVA concentrations. The results from this study suggest that early activation of the rate‐limiting enzyme in the carotenoid biosynthetic pathway and extended fruit maturation time are essential factors to achieve optimal PVA concentrations in banana fruit.