Volume 10, Issue 4, 2010 October-December

Volume 10, No 4 Pages:
2010 October-December Articles: 9

Anthelmintic resistance: the song remains the same

The prevalence of resistance to broad-spectrum anthelmintics among veterinary helminths has dramatically increased and has evolved from a scientific curiosity into a serious crisis facing small ruminant production in many countries. It also poses a veritable threat to other livestock and human helmiths. Both the molecular mechanisms of action and mechanisms of resistance of anthelmintics are poorly understood. Benzimidazoles bind to nematode β-tubulin, preventing microtubule aggregation and leading to paralysis and death. Levamisole acts through nicotinic acetylcholine receptor of the parasite muscle, causing membrane depolarization and contraction resulting in paralysis. Macrocyclic lactones modulate L-glutamate-gated chloride channels present on the pharynx and somatic muscle membrane of the parasites, thereby paralyzing them. Modes of action of schistosomicides and fasciolicides remain incompletely defined. A number of helminths have developed multiple resistance making their control difficult or almost impossible. As chemotherapy remains the mainstay of helminth control, ways of preserving the efficacy of the anthelmintics must be sought. Complete grasp of the molecular events and the underlying Darwinian selection in the parasites is the ultimate challenge if the persistent dilemma is ever to be alleviated, and that goal is yet an unforeseeable vista.

Ethno-medicinal value of some anticancer medicinal plants from north-east India: an in vivo screening in murine tumor model

Considering the importance of natural products in cancer therapy, a preliminary investigation on some anticancer medicinal plants of north-eastern states of India was conducted in murine tumor model. Nine different plants such as Ageratum conizoides Linn. (Asteraceae), Blumea lanceolaria Linn. (Asteraceae), Dillenia pentagyna Roxb. (Dilleniaceae), Potentilla fulgens Wall. (Rosaceae), Taxus baccata Linn. (Taxaceae), Mirabilis jalapa Linn. (Nyctaginaceae), Xanthium strumarium Linn. (Asteraceae), Dillenia indica Linn. (Dilleniaceae) and Gynura conyza Cass. (Compositae) were studied. Out of these, the ethanol extract of D. Pentagyna showed the most potent antitumor activity, i.e. % ILS ~ 55% and % ILS ~ 48% at a dose of 50 and 100 mg/kg/day, respectively; followed by aqueous extract of P. fulgens showing % ILS ~ 37% at a dose of 50 mg/kg/day. Out of different fraction extracts of D. pentagyna and P. fulgens, better antitumor activity was observed with chloroform extract of D. pentagyna (% ILS ~ 89%) and hexane fraction of P. fulgens (% ILS ~ 37%) at a dose of 50 mg/kg/day. A significantly higher antitumor activity of D. pentagyna and P. fulgens seems to be due to the presence of alkaloids and flavonoids. Further detailed studies on its toxicity as well as isolation and structural elucidation of biologically active principle(s) are required.

Calculation of photofield emission current in tungsten by using transfer Hamiltonian method

We present here the results of the calculations of photofield emission current. Free electron potential model was used to describe crystal potential to derive wave functions. Transfer Hamiltonian method was applied for calculation of the transition probability. Photofield emission current is calculated from tungsten. Variation of photofield emission current is explained from the result.

First record of sisorid catfish Glyptothorax indicus Talwar, 1991 (Teleostei: Sisoridae) from Mizoram, India

Glyptothorax indicus, a sisorid catfish, is reported from Mizoram, India, giving a brief description and morphometric characters. Additional characters other than reported in the original description, such as irregular black spot on the posterior region particularly on the caudal peduncle region, and also on the caudal fin are reported. This study provides additional information on the distribution of this species in India, and is first report from Mizoram.

Study of electronic and optical properties of lead telluride (PbTe) by using FP-LAPW method

A theoretical study of electronic and optical properties of PbTe using the full-potential augmented plane waves (FP-LAPW) within density-functional theory (DFT) was presented as implemented in WIEN2k code. We adopted the dipole approximation in our optical calculations. The dielectric function was calculated in the momentum representation, which requires matrix elements of the momentum p between occupied and unoccupied states. We identified the microscopic origin of the main features in the optical spectra and find the factors responsible for most of the optical absorption in this system.

Measurement of indoor concentrations of radon and thoron in Mizoram, India

Radon, thoron and their progenies as a natural radiation hazards to human health is well known. These gases are present in the environment and their level of concentration depends upon geographical and geological conditions, meteorological factors, etc. The indoor radon/thoron concentration is also influenced by building materials, ventilating system and soil gas diffusion. Measurement of radon/thoron concentration in Mizoram is reported in this paper covering three districts, namely Aizawl, Kolasib and Champhai. In this study, we used solid-state nuclear track detectors to obtain the time integrated concentration levels of indoor radon/thoron. The study was conducted by measuring the cumulative exposure for a period of about 90 days each in 149 houses during rainy season (May-August). Houses were selected on the basis of geological characteristics of the area and the construction types in order to determine variation of concentrations of radon and thoron due to these factors. Among the three districts, Champhai District had the highest radon/thoron concentrations, while Kolasib District had the maximum thoron concentration. Among the different types of houses, concrete building had the average maximum concentration of radon followed by Assam type building with G.I. Sheet walls while the contribution due to asbestos walls of Assam type building was found to be lowest.

The birth and death of a star

Scientists believe that nearly 15 billion (15 x 109) years ago the universe originated in a huge explosion, called the ‘Big Bang’. At the time of big bang, the size of the universe was just like a point and all matter, energy, forces were condensed into this point of zero volume and infinite density. Thus the big bang is the creation of everything - all space, energy, force, radiation and even time. The concept of time has no meaning before big bang. In this article, we shall try to explain how a star is born from the giant molecular clouds of hydrogen and helium. Then how a star is evolved and what is the ultimate fate of it. The end products of a star may be a white dwarf or a neutron star. But for a massive star, ultimately it may end up to a black hole by ongoing gravitational collapse.

Effect of fertilizer (NPK) on earthworm population in the agroforestry system of Mizoram, India

The effect of inorganic fertilizer (NPK) on earthworm population was studied for two years (2002-2004) under different plantations at Sakawrtuichhun (SKT) and Pachhunga University College (PUC) agroforestry sites in Mizoram, north-eastern state of India. Five species of earthworms, viz. Drawida sp., Metaphire houletti (Perrier), Perionyx excavatus (Perrier), Perionyx macintoshi (Stephenson) and Eutyphoeus mizoramensis (Julka et al.) under three families were identified in the study sites. Detailed study was carried out under different soil strata and on different age group of earthworms in plantations like maize+Leucena leucocephala (ML) and pine apple+citrus+Leucena leucocephala (PCL). Doses of inorganic fertilizer treatment were given as per state agriculture department recommendation. Earthworms were collected from five random sampling sites at monthly intervals by hand sorting method in each replicate. The most versatile species was found to be Drawida species. An epigeic species, P. excavatus showed significant population variation between NPK treatment and control in both study sites. The one-way ANOVA showed positive impacts of NPK fertilizer treatment on earthworm population. Four species of earthworms excluding the anecic E. mizoramensis showed a significant variation between the two treatments in PCL plantations of PUC. The uppermost stratum (0-10 cm) seemed to be the most affected by fertilizer treatment among the three strata. The Juvenile and immature worms were found to be most influenced by NPK application. The impact of NPK application on earthworm population was greater in PCL plantation compared to ML plantation.

Recent status of threatened birds of Mizoram

According to the latest list of threatened birds of India based on BirdLife International(UK) list of 2010, India is known to have 14 species of critically endangered birds, 17 endangered species, 56 vulnerable species, 3 species of data deficient and 66 near threatened species. A thorough study from the existing literatures reveals that Mizoram is having 18 species of birds (11.53% of India threatened birds) .