Photoperiod and shelter have direct or indirect effects on phenotypic traits expression in different fish species. The present study was, therefore, intended to explore whether these light and shelter could influence some phenotypic traits of African catfish larvae under laboratory condition. Newly hatched larvae were stocked in plastic aquaria (10L) at a rate of 5 individuals/L and reared for one month under four treatments such as 24h light (24L), 24 h dark (24D), 12h light and 12h dark with PVC (12DL_PVC), and 12h light and 12h dark without PVC (12DL) conditions. A total of 108 larvae were sampled for phenotypic traits analysis. The results revealed that complete darkness (24D) significantly improved the overall growth parameters (total length, standard length, caudal peduncle length, anal fin length, caudal fin length, total body depth, dorsal fin length, pre dorsal distance, pre anal distance, pre ventral distance, head width, head length, eye diameter, maxillary barbell length, inter orbital length, and specific growth rate) than all other treatments, while no significant variation was found among other treatments. Although shelter did not show any significant role in the overall growth, it significantly reduced the larval mortality than those reared without shelter. The survival rates were also significantly different among various light regimes in which the highest was found in 24D (86%) followed by 12DL_PVC (74%), 24L (71%), and 12DL (60%). The study also revealed that larvae reared in 24D exhibited maximum dark brown body colouration (63%), while in 24L showed maximum light brown colouration (96%). On the other hand, maximum larvae were appeared as medium brown color (76%) in tanks having PVC, whereas many of them were light brown (61%) in non-PVC tanks. Taken together, the study suggests that C. gariepinus larvae should be reared in completely dark condition to enhance their overall production.
Multiferroic ceramics (Bi 1.1 FeO 3 ) were synthesized by the conventional powder metallurgy route by adopting the melt-phase sintering followed by rapid thermal quenching technique. Effect of sintering temperature on physical, structural, microstructural, electric, and magnetic properties was studied. X-ray diffraction and scanning electron microscopic studies showed that calcination and sintering promoted the desired perovskite (BiFeO 3 ) phase and density of the ceramics. Sintering temperature improved the bulk density of the samples as a result of this leakage current density decreased and electric polarization improved. Sample sintered at 850°C showed bulk density up to 81%. Electric measurements showed spontaneous polarization, remnant polarization, and coercive field of 14.44 lC/cm 2 , 5.47 lC/cm 2 , and 25.50 kV/cm, respectively. Linear behavior of magnetization as a function of applied magnetic field confirms the antiferromagnetic nature of the BiFeO 3 compound at room temperature.
Grey langurs (Semnopithecus spp.) occupy a variety of habitats, ranging from lowland forests and semi-desert to alpine forests. Little is known about their foraging and ranging in alpine forests, which appear to contain less food than lowland forests. We conducted a 1-year study of Himalayan grey langurs (Semnopithecus ajax) in Machiara National Park, Pakistan, where they occur at relatively high altitudes (range 2000-4733 m). We followed three groups of different sizes and compositions and examined the effects of ecological and social factors on ranging and feeding. The home-range sizes of a small bisexual group (SBG), a large bisexual group (LBG), and an all-male group (AMG) were 2.35 ± 0.92 (mean ± SD; average of four seasons), 3.28 ± 0.55, and 3.52 ± 1.00 km(2), respectively, and were largest in winter for all groups. The daily path lengths of the SBG, LBG, and AMG were 1.23 ± 0.28 (mean ± SD; average of four seasons), 1.75 ± 0.34, and 1.84 ± 0.70 km, respectively; that of the LBG was longer in winter, while that of the AMG was shorter in summer. Both the home-range size and daily path length of the AMG were larger than those of the other groups, even after partialling out the effect of group size differences. The mean altitude used by the langurs and the proportion of animals seen feeding did not differ among seasons or group types. As the mean temperature increased, the altitude used by langurs significantly increased for the SBG and LBG, but not for the AMG. On the other hand, as the temperature increased, the home-range sizes significantly decreased for the SBG and AMG, but not for the LBG. Rainfall did not show any correlation with ranging or feeding in any of the groups. Our results suggested that grey langurs in Machiara National Park employ a high-cost, high-return foraging strategy in winter, and that the ranging of the AMG also reflects its reproductive strategy.
α- and β-Galactosidases find application in food processing, health and nutrition. Aspergillus niger is one of the potent producer of these enzymes and was genotypically improved using gamma-ray induced mutagenesis. The mutant-derivative produced two-fold higher α- and β-galactosidases. For testing genetic variability and its relationship with phenotypic properties of the two organisms, DNA samples of the mutant and parental strains of A. niger were amplified with 28 deca-nucleotide synthetic primers. RAPD analysis showed significantly different pattern between parental and mutant cultures. The mutant derivative yielded homogeneous while parental strain formed heterogeneous amplification patterns. Seven primers identified 42.9% polymorphism in the amplification products, indicating that these primers determined some genetic variability between the two strains. Thus RAPD was found to be an efficient technique to determine genetic variability in the mutant and wild organisms. Both wild and mutant strains were analyzed for their potential to produce galactosidases. Comparison of different carbon sources on enzyme yield revealed that wheat bran is significant (P < 0.01) effective producer and economical source followed by rice bran, rice polishing and lactose. The mutant was significantly better enzyme producer and could be considered for its prospective application in food, nutrition and health and that RAPD can be effectively used to differentiate mutant strain from the parental strain based on the RAPD patterns.
The predaceous pentatomid, Oechalia schellembergii (Guérin‐Meneville) (Heteroptera: Pentatomidae) used vision and olfaction to locate Heliothis punctigera (Wallengren) (Lepidoptera: Noctuidae) larvae. Oechalia schellembergii took relatively less time to locate wandering than stationary larvae. Dead, but artificially moved larvae were more prone to attacks than stationary larvae. Predators showed positive response to larval frass, they antennated, probed and carried out an intensive search in its vicinity. Oechalia schellembergii responded to prey that was both concealed and stationary at a close range only. Impairing of antennae had a greater impact on predators searching ability than impairing of eyes and ocelli. Predators without vision failed to differentiate between the anterior and posterior end of the prey and while probing often missed the larva. In contrast, non‐impaired individuals selectively attacked the anterior end of prey. Predators with vision and olfaction blocked showed an unusual search pattern. They searched sporadically with proboscis stretched, and also used front tarsi to locate prey. Prey movement played a major part in prey detection. Slow moving larvae appeared to be perceived less readily by predators than fast moving larvae. Résumé Localisation des proies par Oechalia schellenbergii O. schellenbergii Guerin‐Meneville utilise la vision et l'olfaction pour découvrir ses proies, les chenilles d'Heliothis punctigera Wallenberg. La vision est importante dans la détection des proies en mouvement et l'olfaction aide à la découverte des chenilles immobiles. Les prédateurs consacrent relativement moins de temps à localiser les chenilles mobiles qu'immobiles. Des chenilles mortes mais artificiellement remuées sont perçues et ainsi sujettes à plus d'attaques que si elles étaient immobiles. Les prédateurs réagissent aux excréments des chenilles, ils les touchent avec leurs antennes, les sondent et s'engagent dans une prospection intense aux alentours. Ils ne réagissent qu'à faible distance à une proie cachée et immobile. Le vernissage des antennes semble avoir eu plus d'effet sur la prospection que le vernissage des yeux et des ocelles. Cependant, les punaises dont la vision était compromise ne distinguaient pas les extrémités antérieure et postérieure de la chenille, qui était souvent manquée lors du sondage. Ce sondage des proies était d'ailleurs toujours perturbé; par contre, les individus intacts, attaquaient sélectivement l'extrémité antérieure des chenilles. Le comportement de prospection des punaises, dont la vision et l'olfaction étaient bloquées, était anormal. Elles cherchaient sporadiquement avec leurs rostres, tout en se déplaçant autour de leurs proies, localisées aussi par l'utilisation des tarses antérieurs. Le mouvement de la proie a joué un rôle fondamental dans la détection. Les chenilles lentes ont semblé plus susceptibles d'être découvertes et ainsi attaquées que les rapides.
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