Category Archives: Volume 17 Nos. 1 – 4 (1995)

Ontogenetic Differentiation of Alpha and Beta Esterases in Univoltine, Bivoltine and Trimoulter Races of Silkworm Bombyx mori L.


Author(s): P.J. Raju and N.B. Krishnamurthy

Abstract

Formation of an adult organism from a single fertilized cell is the result of selective differential gene expression, operating on a constant pool of genetic information. The differential gene action can be viewed by the differential synthesis and activity of certain enzymes. The variation patterns in two enzyme systems of alpha and beta esterases have been studied in a univoltine race I-380, bivoltine NB4 D2 and in a trimoulter race of silkworm Bombyx mori L. In total, 10 different development stages of each of the races were analysed. The number of brands and their intensity varied during different developmental stages indicating differential gene action. The pattern of variation of enzyme bands and their significance are herein discussed.

Keywords : Bombyx mori. Esterases. Isozymes. Ontogeny.

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Moisture Adsorption Isotherms of Copra at Different Temperature


Author: Lemuel M. Diamante

Abstract

The moisture adsorption isotherms of tapahan dried copra were determined at 22, 30 and 38°C. The isotherm of copra at different temperatures were of type III according to the BET classification. Equilibrium moisture content of copra at a given water activity increased as temperature decreased. The Henderson equation gave better fit of the adsorption isotherms of copra at each given temperature, followed by Oswin and Caurie equations, respectively. A modified Henderson equation can describe the effect of temperature on the adsorption isotherms of copra. The critical moisture contents of copra with respect to mold growth and aflatoxin production decreased as temperature increased. Aflatoxin production had higher critical moisture content than mold growth only.

Keywords : Aflatoxin. Aspergillus flavus. Copra. Moisture adsorption.

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Comparative Socioeconomic Analysis Between Hand Pounding and Micro Rice Mill Processing in Matalom, Leyte


Author(s): Fe M. Gabunada, Dolores L. Alcober and Nestor O. Morales

Abstract

This study was conducted to make comparative evaluations on the socioeconomic aspects of two methods of processing paddy rice, namely: hand pounding and micro rice mill processing. The micro rice mill designed by the International Rice Research Institute (IRRI) was introduced to women’s associations in three upland barangays of Matalom, Leyte and was found to be the better alternative to the conventional manual method. It is capable of processing small quantities of paddy rice with certain level of efficiency and standards.
Hand pounding of paddy rice is more time-consuming than processing by the use of a micro rice mill. Since women in the study areas have other productive activities and income opportunities, the use of a micro rice mill gave more free time to women. Milling and head rice recovery were better than in hand pounding. It was found to be economical and practical for women to process paddy rice using the micro rice mill.
In addition, the quality of rice and rice bran was better with the introduced technology. Hence, cooperators preferred the use of the micro rice mill and recommended its use to their friends and relatives.

Keywords : Hand pounding. Head rice recovery. Micro rice mill. Milling recovery. Paddy rice. Rice processing. Socioeconomic analysis.

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Determination and Analysis of Somatic Chromosome Numbers in Sweetpotato Cultivars, Related Ipomoea Species, and Interspecific Hybrids


Author: Marilyn Z. Oracion

Abstract

The somatic chromosome numbers (2n) in seven sweetpotato cultivars, four diploid (2x) Ipomoea species, tetraploid (4x) and hexaploid (6x)I. trifida strains, and twenty selected hybrids between sweetpotato and 6xl. Trifida were determined using a Fealgen-acetocarmine squash technique designed for Ipomoea chromosomes. The data revealed that euploid counts of 2n=30, 60 and 90 were the modes for the 2x, 4x, and 6x Ipomoea, respectively. These counts coexisted with aneuploidy cells having either less (hypoploid) or more (hyperploid) chromosomes that the euploid or modal counts. The hypoploid cells were majority among the aneuploidy variants. The percentage frequency ratio of euploid to aneuploid cells were 60%:40% among diploids, 45%:55% among tetraploids, and 30%:70% and 34%:66% amon the 6x I.trifida and sweetpotatoes, respectively. The wide hybrids exhibited extreme aneuploidy with 16%:84% euploid to aneuploidy cell ratio. Two hybrids did not show cells with 2n=90. In general, the hybrids resembled the sweetpotato parents in having chromosome numbers closer to 6x or 90 whereas the 6x I.trifida and the 4x strains exhibited somatic counts encompassing the 2x, 4x and 6x counts. The results suggest that the prevailing cytogenetic system among the Ipomoea is that of somatic euploidy-polyploidy combined with aneuploidy. Further, the amount of aneuploidy cells appeared higher with taxa of higher ploidy and highest among the hybrids. The findings are discussed in relation to sweetpotato breeding, germplasm conservation and evolution of new phenotypes through vegetative propagation.

Keywords : Aneuploidy. Cytogenetics. Euploidy. Evolution. Ipomoea. Somatic cells. Sweetpotato breeding. Wide hybrids. 2n.

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Distribution, Infection and Symptomatology of Virus-like Diseases of Cucurbits in the Visayas


Author(s): Manuel K. Palomar, Ruben M. Gapasin and Honey S. I. Vega-Colis

Abstract

Surveys in different localities of Bohol, Cebu, Leyte and Samar revealed that 13 virus-like diseases infect cucurbits, namely: ampalaya and patola abnormality (APA), ampalaya leaf curl (ALC), ampalaya little leaf (ALL), ampalaya mosaic (AM), chayote little leaf (CLL), cucumber mosaic (CM), patola little leaf (PLL), squash mosaic (SM), squash leaf curl (SLC), squash yellow mosaic (SYM), upo mosaic (UM), watermelon mosaic (WM), and watermelon leaf curl (WLC). The infection of these diseases ranged from <1-100%, with no discrete pattern of infection observed. Of these 13 virus-like diseases, ALL, SM, and UM were commonly observed and showed a significantly higher percentage infection in the four provinces; however, CM showed the highest average infection of 80% in Bohol. Likewise, Leyte was observed to have the most varied kinds of virus-like diseases in cucurbits as compared to Bohol, Cebu, and Samar, in descending order. Symptoms of the disease varied from yellow and green mosaic, yellowing chlorotic flecks, vein clearing, mottling to malformation of leaves.

Keywords : Cucurbitaceae. Disease distribution. Symptomatology. Virus-like diseases. Visayas.

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