Identification of a putative germ plasm in the amphipod Parhyale hawaiensis

Background: Specification of the germ line is an essential event during the embryonic development of sexually reproducing animals, as germ line cells are uniquely capable of giving rise to the next generation. Animal germ cells arise through either inheritance of a specialized, maternally supplied cytoplasm called 'germ plasm’ or though inductive signaling by somatic cells. Our understanding of germ cell determination is based largely on a small number of model organisms. To better understand the evolution of germ cell specification, we are investigating this process in the amphipod crustacean Parhyale hawaiensis. Experimental evidence from previous studies demonstrated that Parhyale germ cells are specified through inheritance of a maternally supplied cytoplasmic determinant; however, this determinant has not been identified. Results: Here we show that the one-cell stage Parhyale embryo has a distinct cytoplasmic region that can be identified by morphology as well as the localization of germ line-associated RNAs. Removal of this cytoplasmic region results in a loss of embryonic germ cells, supporting the hypothesis that it is required for specification of the germ line. Surprisingly, we found that removal of this distinct cytoplasm also results in aberrant somatic cell behaviors, as embryos fail to gastrulate. Conclusions: Parhyale hawaiensis embryos have a specialized cytoplasm that is required for specification of the germ line. Our data provide the first functional evidence of a putative germ plasm in a crustacean and provide the basis for comparative functional analysis of germ plasm formation within non-insect arthropods

Indian SMEs Perspective for election of ERP in Cloud

With increasing market competition and globalization, SMEs have shown interest to deploy ERP package to integrate their business processes. High investment in terms of cost, manpower and time are the major hurdles while selecting a traditional ERP package. Hence there is a need to look for a cost effective ERP solution. Deploying ERP on Cloud is one such option due to lower infrastructure cost and flexible payment. A SME evaluates an ERP solution from Economical, Technological and People perspectives with the factors that measure them. . . A factor can either be a benefit or a threat. A benefit facilitates whereas a threat holds back SMEs decision to adopt ERP in cloud. This research provides a benefit- threat framework on Economical, Technological and People perspective that a SME perceives while selecting ERP in cloud environment. The framework is validated and it suggests that Economical and Technological are two important perspectives while selection of ERP on cloud for a SME

Phytosociology and pedological characteristics of selected beats of Durgapur Forest Range, West Bengal, India

The aim of the investigation was to analyze phytosociological characteristics and diversity pattern of five selected beats of tropical dry deciduous forest of Durgapur Forest Range, Burdwan, West Bengal, India. The present investigation was carried out through quadrat method for analysis of phytosociological aspect of vegetation. The soil of the different study sites were analyzed by following standard methodology. The results reflect dominancy of dicotyledons over monocotyledons in the five studied sites. Basudha (61) and Shibpur (58) beats represents higher number of species among the five studied sites. Maximum IVI value was recorded by Shorea robusta followed by Madhuka longifolia among all the beats except Shibpur. The study represents overall dominance of Sal forest over the entire region. Therefore Basudha and Shibpur beat needs prior conservative measure for protection of bioresources in those two forest region. The soil characteristics of the four study sites revealed acidic nature of soil in all the studied sites of Durgapur Forest Division. The range of organic carbon % was found to be higher in amount in comparison to conventional soil samples reflecting higher soil fertility of the studied sites. Therefore, proper management and conservative measures needs to be implemented for conservation of bioresources in different sites of Durgapur Forest Division, West Bengal, India

An EOQ model for time-dependent deteriorating items with alternating demand rates allowing shortages by considering time value of money

The present paper deals with an economic order quantity (EOQ) model of an inventory problem with alternating demand rate: (i) For a certain period, the demand rate is a non linear function of the instantaneous inventory level. (ii) For the rest of the cycle, the demand rate is time dependent. The time at which demand rate changes, may be deterministic or uncertain. The deterioration rate of the item is time dependent. The holding cost and shortage cost are taken as a linear function of time. The total cost function per unit time is obtained. Finally, the model is solved using a gradient based non-linear optimization technique (LINGO) and is illustrated by a numerical example

Broad-tailed force distributions and velocity ordering in a heterogeneous membrane model for collective cell migration

Correlated velocity patterns and associated large length-scale transmission of traction forces have been observed in collective live cell migration as a response to a "wound". We argue that a simple physical model of a force-driven heterogeneous elastic membrane sliding over a viscous substrate can qualitatively explain a few experimentally observed facts: (i) the growth of velocity ordering which spreads from the wound boundary to the interior, (ii) the exponential tails of the traction force distributions, and (iii) the swirling pattern of velocities in the interior of the tissue.Comment: 7 pages and 5 figure

Sufficient conditions for the additivity of stall forces generated by multiple filaments or motors

Molecular motors and cytoskeletal filaments work collectively most of the time under opposing forces. This opposing force may be due to cargo carried by motors or resistance coming from the cell membrane pressing against the cytoskeletal filaments. Some recent studies have shown that the collective maximum force (stall force) generated by multiple cytoskeletal filaments or molecular motors may not always be just a simple sum of the stall forces of the individual filaments or motors. To understand this excess or deficit in the collective force, we study a broad class of models of both cytoskeletal filaments and molecular motors. We argue that the stall force generated by a group of filaments or motors is additive, that is, the stall force of $N$ number of filaments (motors) is $N$ times the stall force of one filament (motor), when the system is in equilibrium at stall. Conversely, we show that this additive property typically does not hold true when the system is not at equilibrium at stall. We thus present a novel and unified understanding of the existing models exhibiting such non-addivity, and generalise our arguments by developing new models that demonstrate this phenomena. We also propose a quantity similar to thermodynamic efficiency to easily predict this deviation from stall-force additivity for filament and motor collectives.Comment: 14 pages, 7 figure