Preliminary studies on the conversion of Tubifex tubifex as food by elvers of Anguilla nebulosa (Gray and Hardwicke)

Elvers of Anguilla nebulosa were reared at 23°C in confined waters and their food intake, growth and conversion efficiency (K₁:%) were studied. Elvers weighing 278.33±14.35 mg were fed on an ad libitum diet of the oligochaete worm Tubifex tubifex for 60 days. On an average, the test individuals consumed 99.55±19.81 mg food/elver/day amounting to 35.76% of the initial biomass; during the corresponding period the elvers exhibited a growth rate of 5.03±2.42 mg gain in weight/elver/day which is equivalent to 5.06% of the consumed food. Thus the 'housekeeping' of these elvers may be regarded as established. In 50 days, the food required amounts to 0.358±50 = 17.90 times the initially stocked biomass. That is, 1 kg of initially stocked elvers may need 17.90 kg of T. tubifex to produce 0.912 kg of elver meat. A poor conversion ratio of 20 : 1 may be one reason for the slow growth of the elvers.     

Surface area‐to‐volume ratio,not cellular viscoelasticity,is the major determinant of red blood cell traversal through small channels

The remarkable deformability of red blood cells (RBCs) depends on the viscoelasticity of the plasma membrane and cell contents and the surface area to volume (SA:V) ratio; however, it remains unclear which of these factors is the key determinant for passage through small capillaries. We used a microfluidic device to examine the traversal of normal, stiffened, swollen, parasitised and immature RBCs. We show that dramatic stiffening of RBCs had no measurable effect on their ability to traverse small channels. By contrast, a moderate decrease in the SA:V ratio had a marked effect on the equivalent cylinder diameter that is traversable by RBCs of similar cellular viscoelasticity. We developed a finite element model that provides a coherent rationale for the experimental observations, based on the nonlinear mechanical behaviour of the RBC membrane skeleton. We conclude that the SA:V ratio should be given more prominence in studies of RBC pathologies.     

Short term effect of ultraviolet-B radiation on photosystem 2 photochemistry in the cyanobacteriumSynechococcus 6301

Exposure of intact cells of theSynechococcus 6301 to UV-B radiation induced a loss in photosystem 2 (PS 2) electron transport activity prior to the alteration in pigment complexes. Thus the degradation of PS 2 was not directly related to pigment alteration. Supported by Young Scientist grant No. SRJSYIB-05192 from the Department of Science and Technology, Goverment of India to SDSM.