• Volume 98, Issue 4

      August 1988,   pages  227-316

    • Computer-assisted image analysis in biological sciences

      Donat-P Häder

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      Automated computer-controlled image analysis of digitized video images has developed into a versatile tool useful for many applications. Both on the macroscopic and microscopic scales counting, identification and tracking are facilitated by these techniques which allow a quantitative, fast and objective analysis. Though image analysis has not yet reached the capabilities of the human eye and brain, it helps in both routine analysis and research tasks. Future enhancements made possible by the availability of larger memories and higher processing speeds will enhance the realm of applications. Especially the use of pipeline processing and dedicated hardware for the routines of image manipulation, including averaging and Laplace filtering, will open new fields of use. The most difficult task to master will be the extraction of complex parameters necessary for object recognition in an image, which requires a high degree of built-in intelligence both on the hardware and software level. Another ambitious task to tackle is the analysis of image sequences in order to track several individuals in a population in parallel.

    • Anther development inXylopia nigricans

      K Periasamy S Thangavel

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      In the anther primordium ofXylopia nigricans, the archesporium differentiates discontinuously with intervening sterile tissue. Each archesporial cell divides periclinally and develops into a micro-sporangium with a single microspore mother cell. Thus the anther becomes multisporangiate. The tapetal cells are uninucleate. Cytokinesis of the microspore mother cell is by successive cell plate formation. The pollen development is traced and the significance of the development is discussed.

    • Endosperm controls symmetry changes in the developing embryos of angiosperms

      K V Krishnamurthy

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      During development the angiosperm embryo passes through the filamentous, globular and the cotyledonary phases after undergoing symmetry changes at each of these three steps. Evidences are presented to implicate endosperm control on embryo symmetry.

    • Wandlabyrinthe in the embryo sac ofNigella damascena Linn.

      M R Vijayaraghavan Gayatri Misra Vedantam Sujata

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      The embryo sac ofNigella damascena, with wall ingrowths over entire surface and distinctly formed wandlabyrinthe at the poles, displays a well integrated model for short distance transport of nutrients. The degenerating nucellus creates an influx of metabolites into the embryo sac. The embryo sac wandlabyrinthe play a dual role—initially aid with the influx of metabolites into the embryo sac, but later participate in endosperm wall formation. The two synergid apices exhibit prominent filiform apparatus which function differently. One of the synergids degenerates immediately after fertilization where filiform apparatus helps in receiving the pollen tube. The other undamaged synergid persists along with filiform apparatus upto the octant embryo stage and this filiform apparatus probably facilitates short distance metabolite transport into the synergid. The antipodal cells show 3 types of wall ingrowths—(i) wall ingrowths at the antipodal-nucellus interface which are long, branched and spread fan-like into the antipodal cytoplasm, indicating the flow of metabolites into the antipodes from the nucellus, (ii) inter-antipodal wall-ingrowths that are small, papillate and present on both sides of the wall indicating the exchange of metabolites between the antipodes and (iii) wall labyrinths at the antipode-central cell interance which are very small and are directed into the antipode cytoplasm.

    • Isolation of a cytokinin-binding protein fromCucumis sativus cotyledons

      C Jayabaskaran

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      A cytokinin-binding protein which exists as monomer and dimer was isolated from cucumber (Cucumis sativus L. var Guntur) cotyledons by affinity chromatography on AH-Sepharose-pi6 Ap /s> column. The protein bound to [3H]-N6-(Δ2-isopentenyl) adenosine trialcohol. On Sephadex G-50 chromatography it gave 2 peaks corresponding to molecular weight 4000 and 8000 daltons. On sodium dodecyl sulphate-polyacrylamide gel electrophoresis, it gave only one band with an apparent molecular weight of 4000 daltons.

    • Growth and metabolism in cotton and tobacco callus cultures

      P B Kavi Kishor A R Mehta

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      Activities of key enzymes of glycolytic and pentose phosphate pathways and krebs cycle were less in tobacco callus than in cotton callus cultures grown under identical conditions. The initial period of growth was characterized by high activities of invertase, acid phosphatase, hexokinase, fructose diphosphate aldolase, malate dehydrogenase, succinate dehydrogenase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase; the activities of these enzymes declined during the remainder period of growth.

    • Response of pigeon pea to variable levels of manganese

      C P Sharma Neena Khurana C Chatterjee S C Agarwala

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      Pigeon pea (Cajanus cajan (L.) Millsp.) cv. T21 was grown in refined sand at manganese levels ranging from 0-0011 to 5·5 mg 1−1. At less than 0·055 mg Mn 1−1, growth was depressed. In manganese deficient plants, there was reduction in the area and number of leaves. A reduction in seed yield was observed at low and excess manganese and was optimum at 0·55 mg Mn1−1. Manganese deficient plants showed enhanced levels of peroxidase and ribonuclease activity and caused reduction in chlorophyll content, sugars, Hill activity and activities of catalase, acid phosphatase and aldolase. When manganese supply was low, manganese concentration in leaves decreased and iron, zinc, copper and phosphorus concentrations increased. Values for deficiency, threshold of deficiency and toxicity of manganese in leaves were respectively 25, 39 and 190·5 μg g−1 and in seeds they were 10·6, 12·8 and 18·2 μg g−1 dry matter.

    • Aflatoxin-producing fungi in stored paddy

      B M Sundaram Rajkumar Krishnamurthy S Subramanian

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      Stored paddy (150 samples) collected from 3 different storehouses in Tamil Nadu and threshed rice grains (20 samples) from local warehouses and retailers were assayed for the extent of fungal contamination by blotter and dilution plate methods. The contaminated samples that fluoresced in UV light and cultures of fungi isolated from stored samples were subjected to chemical extraction for aflatoxins. Aflatoxin B1 was detected in 7 out of 17 isolates ofAspergillus flavus and 1 out of 6Aspergillus parasiticus. Moisture content of the samples was correlated with the number of fungi isolated and the type of storehouse from which the samples were collected.

    • Degradation of carbofuran and carbaryl by a suspension from a flooded soil incubated at 35°C and retreated with carbofuran

      K Ramanand M Sharmila N Sethunathan

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      An enrichment culture was prepared by repeated additions of carbofuran to a flooded alluvial soil that was incubated at 35°C. In a mineral salts medium inoculated with this enrichment culture and then incubated at 35°C, more than 90% of the14C-carbofuran and14C-carbaryl were lost within 5 and 3 days of inoculation respectively; during the same period no appreciable loss of both insecticides was noticed in the uninoculated medium. Carbofuran was degraded by the enrichment culture at a concentration as high as 1000 μg ml−1. Addition of ammonium nitrogen to the medium temporarily slowed down the degradation of carbofuran by enrichment culture.

    • Biomass structure and net primary production of Siwalik chir pine (Pinus roxburghii Sarg.)-mixed broadleaf forest

      B S Rana S P Singh R P Singh

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      Biomass and net primary production of chir pine (Pinus roxburghii Sarg.)-mixed broadleaf forest is described. The total forest biomass (about 199 t ha−1) and net primary production (12·4 t ha−1 yr−1) did not reveal marked differences from similar aged central Himalayan chir pine forests. Trees accounted for most of the biomass and net primary production.

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