Effects of different types of feeds on growth and production of tiger shrimp, Penaeus monodon at Bagerhat region, Bangladesh

An experiment was carried out in farmers' gher (shrimp farm) at Bagerhat sadar upazilla, Bagerhat to ascertain the effects of three different types of feeds on the production and economics of brackishwater shrimp, Penaeus monodon for a period of 120 days. There were three treatments such as T1 (BFRI dough feed containing of 30% fish meal, 10% protein conc., 10% soya meal, 15% mustard oil cake, 18% rice bran, 5% maize, 10% wheat flour, 1% oyster shell powder and 1% vitamin premix), T2 (Commercial diet Saudi-Bangla grower) and T3 (Saudi-Bangla special feed). Each treatment had two replicates and the stocking of shrimp in each gher was 3 nos/m². Water quality parameters did not differ significantly among the treatments except water depth. Average production and net return of shrimp in different treatments varied from 404.0 to 509.0 kg/ha and Tk. 56,493.99-Tk. 84,209.60, respectively. T2 showed significantly (p<0.05) the highest production and economic return. The result of the study implied that T2 is more suitable and economically viable than that of other treatments for shrimp farming.

Inventors and entrepreneurs in academia: What types of skills and experience matter?

This paper aims to improve our understanding of the attributes of academic researchers that influence the capacity to contribute to technical advance, by adding to the pool of technological opportunities available to industry or engaging in the exploitation of entrepreneurial opportunities. We investigate a number of factors associated with the skills developed by academic researchers. We find that contributions to the pool of technological opportunities and exploitation of entrepreneurial opportunities involve different sets of skills and expertise of scientists. Our results show that the former is driven by academic scientists research excellence and discovery of earlier technological opportunities and the latter is driven by previous collaboration with industry partners, scientific breadth and experience of technological discovery. © 2011 Elsevier Ltd. All rights reserved.

Discovery and characterization of two types of liver-expressed antimicrobial peptide 2 (LEAP-2) genes in rainbow trout

The sequences and gene organisation of two LEAP-2 molecules (LEAP-2A and LEAP-2B) from rainbow trout, Oncorhynchus mykiss are presented. Both genes consist of a 3 exon/2 intron structure, with exon sizes comparable to known mammalian genes. LEAP-2A notably differs from LEAP-2B in having larger introns and a larger 3'UTR. The predicted proteins contain a signal peptide and prodomain, followed by a mature peptide of 41 aa containing four conserved cysteines. The RXXR cleavage site to release the mature peptide was also conserved. Both genes were found to be constitutively expressed in the liver, with expression in the intestine, and to a lesser extent the skin, evident after bacterial challenge. (C) 2004 Elsevier B.V. All rights reserved.

Life history characteristics of three types of females in Brachionus calyciflorus Pallas (Rotifera) fed different algae

This study describes the life history characteristics of amictic, unfertilized mictic and fertilized mictic females of the rotifer Brachionus calyciflorus cultured individually on two different algae at 0.1 mg ml(-1) food concentration and 27 degreesC. The duration of the juvenile period of amictic females was significantly shorter on Chlorella pyrenoidosa Chick than on Scenedesmus obliquus Kutz or both algae together. The duration of the juvenile period of unfertilized mictic females was significantly longer, and the number of eggs produced by amictic females was significantly larger on Chlorella pyrenoidosa than on S. obliquus. When fed the same type of alga, the duration of the juvenile period of the fertilized mictic females was the longest among the three types of females, and the durations of the reproductive period of the amictic females and the post-reproductive period of the fertilized mictic females were longer than, or equal to those of the other two types of females, respectively. The number of eggs produced by an unfertilized mictic female was the largest among the three types of females, and that of amictic females was larger than or equal to that of fertilized mictic females, depending on the type of diet.

The effect of food concentration on the life history of three types of Brachionus calyciflorus females

The effect of food concentration on the life history of three types of Brachionus calciflorus females (amictic, unfertilized mictic and fertilized mictic female) was studied with replicated individual cultures at 25 degrees and at four food concentrations (1.5, 3.0, 6.0 and 9.0 x 10(6) cells mL(-1)) of Scenedesmus obliquus. There were highly significant effects of both food concentration and female type, independently and in interaction on the duration of juvenile period of the rotifer, but neither a;ere the effects on the duration of post-reproductive period and mean life-span. The duration of juvenile period of unfertilized mictic female at the food concentration of 9.0 x 10(6) cells mL(-1) was the longest among all the food concentration-female type combinations. Both food concentration and female type influenced significantly the duration of reproductive period and the number of eggs produced by each type of female per life cycle, respectively. There was, however, no significant interaction between food level and female type. Among the three types of females, the number of eggs produced by an unfertilized mictic female was the largest. and that of a fertilized mictic female was the smallest.

STUDY ON THE MODE OF PRIMARY CONTROL IN THE EGG OF GYNOGENETIC CRUCIAN CARP FOR INHIBITING THE DEVELOPMENT OF 2 TYPES OF SPERM NUCLEI

By comparing the different developmental characteristics of two types of sperm nuclei which were from gynogenetic fish (crucian carp) and amphimictic fishes (red carp, red goldfish and sex-reversal red carp) respectively in the eggs of gynogenetic crucian carp, it was preliminarily revealed that there existed selective inhibiting actions of the primary control in the eggs of crucian carp for inhibiting the development of the two types of sperm nuclei. To homologous sperms, the primary control showed weak effect, thus leading to the decondensation of homologous sperm nuclei at different degrees in the eggs of crucian carp. But to heterologous sperms, the primary control showed strong effects, resulting in the total inhibition of the development of heterologous sperm nuclei. Moreover, our experimental results also showed that the different developmental behavior of the two types of sperm nuclei might have a great relationship to the changes of the sex ratio in the population of gynogenetic crucian carp. The infiltration of "the genetic materials in sperm nuclei" into the female nucleus at random might play an important role in male emergence in the naturally gynogenetic population of crucian carp.