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Soils deficient in P are widespread in major rice (Oryza sativa L.) ecosystems. In view of declining reserves of rock phosphate and the rising costs of P fertilizers, breeding rice varieties tolerant to low P has become important for future food security. Four different methods (hydroponics without sand [H], hydroponics with sand [HS], large pots with soil [PS], and glasses with soil [GS]) were evaluated using rice aus variety Nagina 22 (N22) and its known gain-of-function (gof) and loss-of-function (lof) mutants to screen for low P tolerance in the field. In -P (no addition of NaH2PO4) shoots, dry weight was significantly higher in gof mutant NH787 than in N22 in HS, PS, and GS but not in H, with fold increases of 1.8 in HS, 5.2 in GS, and 9.4 in PS. In HS, in -P, out of six traits only shoot dry weight was significantly higher in gof and lower in lof mutants. However, in GS both root and shoot dry weight could confirm gof and lof mutants. It took 40 d in GS and 70 d in PS to differentiate between growth in -P/low P and +P (0.32 mM NaH2PO4) and between gof and lof mutants. Thus, shoot dry weight at 30 d in HS and root and shoot dry weight at 40 d in GS are best to differentiate between genotypes grown in -P/low P and +P soil and also between gof and lof mutants for low P tolerance. The HS method can be performed in ambient conditions and needs 70% less medium compared with H. If germplasm is to be screened for low P tolerance on a large scale and if there is no access to low-P soil, then screening using HS is the best approach. [ABSTRACT FROM AUTHOR]

The role of leaves, stem and reproductive parts in 14CO2 fixation and subsequent photosynthate translocation was studied in Indian mustard {Brassica juncea L.) at three growth stages. The data mdicated that leaves, stem and pods are important sources of photosynthates for seed filling. At bud emergence stage leaves are the principle site of 14CO2 fixation. The contribution of leaves declines at subsequent stages, where as the contribution of pod walls increased from bud emergence stage to ripening stage. The contribution of the stem remains more or less constant at all three growth stages studied. Although stem can fix 14CO2, at bud emergence and flowering stages it imported 14C-photosynthates from leaves. However, stem exported photosynthates during subsequent growth stages. [ABSTRACT FROM AUTHOR]

The immune mechanisms operating on the sheath and the cuticle of the Brugia pahangi microfilariae have been studied in vitro. The intact and exsheathed parasites were used for this purpose with serum from albino rats immunized with sonicated homogenates of the parasites as the source of anti-bodies. The IgG component of the serum was found to promote adherence of rat leucocytes and death of the sheathed and exsheathed parasites in presence of fresh normal serum. EDTA and EGTA abolished the adherence activity suggesting the involvement of complement components via the classical pathway. Both macrophages and neutrophils participate in this reaction. Eosinophils exhibit marginal activity only on exsheathed parasites. The intensity of adherence and killing by neutrophils in the presence of immune serum was greater with the exsheathed microfilariae than with the sheathed ones. [ABSTRACT FROM AUTHOR]

The nature of immunoglobulin and effector cells involved in the antibody-dependent cell-mediated adhesion and cytotoxicity to Wuchereria bancrofti larvae has been investigated. Human neutrophils and eosinophils purified from peripheral blood by metrizamide gradients readily adhered to the parasites in presence of IgG fraction of sera from majority of elephantiasis cases with amicrofilaraemia and many of the endemic normals. The cells from normal, microfilariae carriers and elephantiasis cases were equally effective in the adhesion reaction. While the adhered neutrophils killed the larvae, eosinophils were ineffective in this respect. DEC treatment of elephantiasis cases results in a significant reduction in the ability of their sera to promote cellular adhesion. [ABSTRACT FROM AUTHOR]

The multimammate rat Mastomys natalensis, when infected with the filarial parasite Acanthocheilonema viteae, develops amicrofilaraemia. Worm recovery and the duration and intensity of microfilaraemia were analysed and related to the humoral and cellular immune responses of the host by using an antibody-dependent cell-mediated cytotoxicity (ADCC) assay towards microfilariae (Mf). Mf were detected in the peripheral blood at 7 weeks post-infection (p.i,), reaching maximum levels by 20 weeks p.i., and then gradually decreasing to undetectable levels during the next 36 weeks. The cytotoxic antibodies appeared around 15-18 weeks p.i., and the serum at 36 weeks pi, induced 70% cytotoxicity to the Mf in vitroin the presence of host cells. The IgM fraction of the immune serum from a microfilaraemic Mastomys promoted ADCC to Mf both in vitro and in vivo. Macrophages were more potent in inducing cytotoxic effect than eosinophils and neutrophils. Platelets were ineffective in killing the Mf in the presence of immune serum. IgM antibody cleared the circulating Mf from the blood when given passively to infected Mastomys. The average recovery of adult worms was about 20% of the inoculated larvae. No live females could be recovered 56 weeks p.i. Thus protective immune responses built up over an extended period of time are elicited against the Mf and perhaps even to adults in Mastomys infected with A. viteae. [ABSTRACT FROM AUTHOR]

Active Brugia pahangi microfilariae (Mf) were injected into naive male BALB/c mice intraperitoneally. Microfilaraemia was studied for 28 days; and Mf circulated in blood in optimum numbers from 3 to 14 days. Anti-Mf respose was assessed by the rate of disappearance of Mf from blood as well as their absence from visceral organs. Sonicated antigens of Mf (MfE) and whole worm extract of adults (WWE) induced absolute protection against the establishment of Mf in mice. This potent anti-Mf response elicited by sonicated antigens was intense, rapid and withstood repeated challenge infection. In comparison, immunization with in vitro excretory, secretory and metabolic antigens of Mf (MfESM) produced a partial but significant level of protection. Sera collected periodically from immunized animals showed antibody by micro-ELISA compared to sham- vaccinated controls. When Mf were used as targets along with the peritoneal exudate cells in vitro. sera from mice immunized with MfE and MIESM showed about four-fold cellular adherence to (Mf-ADCA) and 10-fold killing (Mf-ADCC) of Mf which was antibody-dependent. Some degree of correlation was apparent when the antibody levels, Mf-ADCA/Mf-ADCC activity, and Mf clearance were compared. This murine microfilaraemia model was therefore shown to be suitable for studying the host-protective immune response against filarial parasites. [ABSTRACT FROM AUTHOR]

The complement of fresh normal rat serum was activated by filarial eggs and microfilariae (mf). C3 was deposited on the surface of Litomosoides carinii, Brugia pahangi, Brugia malayi and Dipetalonema viteae as seen by immunofluorescence. Inira-uterine and in vitro-derived mf did not bind C3. In contrast, C3 bound to the blood-derived mf of B. pahangi and B. malayi as well as exsheathed mf of L. carinii and B. malay. Significant consumption of complement was observed with eggs of all filarial species, as well as sheathed mf of B. pahangi, B. malayi and exsheathed mf of L. carinii and B. malayi. These experiments indicated that complement was activated by filarial parasites via the alternative pathway. The bound complement promoted neutrophil-mediated adherence and cytotoxicity. [ABSTRACT FROM AUTHOR]

The lipids of different developmental stages of Culex pipiens fatigans, vector of bancroftian filariasis, have been investigated. The phospholipid composition of the developmental stages and of the subcellular fractions of fourth instar larvae of the insects were analyzed. The composition of fatty acids and their positional distribution have also been examined in the major phospholipids of the larvae. The insect eggs contained higher amounts of lipids than larvae suggesting that they were utilized during embryogenesis. Phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) comprised over 75% of the insect phospholipids. Of these, PE was present in the greatest amounts during all stages of growth and in the subcellular fractions of larvae. An ethanolamine containing sphingolipid was found as a component of the phospholipids of the insects. About 50% of the lipids of the larvae were localized in the cell debris and nuclei fraction which also contained most of the lysolipids of the insects. As in other Diptera 16∶0, 16∶1 and 18∶1 were the major fatty acids present in the insect lipids of which the fatty acid found in greatest amounts was 16∶1. Similar to the phospholipids of animal species, saturated fatty acids were predominantly linked to the 1 position of the major phospholipids of the insects while the unsaturated fatty acids were in higher amounts at the 2 position. [ABSTRACT FROM AUTHOR]

A field experiment was conducted to assess the genotypic variability in 41 divergent barnyard millet (Echinocloa frumentaceae L.) genotypes. A high degree of variation was observed for photosynthesis and other related characteristics. However, for specific leaf weight (SLW), the differences amongst genotypes were non-significant. The seasonal means of photosynthetic rate (A), stomatal conductance (gs), transpiration (E), A/Ci ratio and total dry matter at harvest were positively and significantly correlated. None of the other parameters showed any significant relationship with total dry matter recorded at harvest. Leaf photosynthetic rate showed a positive but non-significant relationship with SLW, and it is suggested that photosynthesis rate seems to be the best selection criterion in barnyard millet. A strong and positive relationship was observed between A/E ratio, A/Ci ratio and A/gs ratio, indicating that both A/Ci ratio and A/gs had a strong influence on the water use efficiency of the leaf. [ABSTRACT FROM AUTHOR]