35,458 research outputs found
The Malaise Trap: Its Utility and Potential for Sampling Insect Populations
Slightly over three decades have elapsed since Malaise (1937) first published plans for the insect trap now bearing his name a stationary mesh tent with open sides, a central baffle, and a top-mounted collecting apparatus (Fig. 1). A non-attractant device, the Malaise trap is based upon the observation that most flying insects hitting an obstacle respond by flying (or crawling) upward (and thus into captivity).
In recent years, the Malaise trap has become increasingly popular among insect taxonomists and collectors as a means of augmenting catch and collecting rare or ephemeral representatives. Many variations have been developed (e.g., Townes, 1962; Gressitt and Gressitt, 1962; Marston, 1965; Chanter, 1965; Butler, 1965), most aimed at making the trap more portable and/or efficient for collecting a particular insect group. To date, however, the Malaise trap has received little notice among other biologists, although it would appear to have considerable potential in almost any field study involving flying insects, and particularly in ecological investigations
The developmental cell biology of Trypanosoma brucei
Trypanosoma brucei provides an excellent system for studies of many aspects of cell biology, including cell structure and morphology, organelle positioning, cell division and protein trafficking. However, the trypanosome has a complex life cycle in which it must adapt either to the mammalian bloodstream or to different compartments within the tsetse fly. These differentiation events require stage-specific changes to basic cell biological processes and reflect responses to environmental stimuli and programmed differentiation events that must occur within a single cell. The organization of cell structure is fundamental to the trypanosome throughout its life cycle. Modulations of the overall cell morphology and positioning of the specialized mitochondrial genome, flagellum and associated basal body provide the classical descriptions of the different life cycle stages of the parasite. The dependency relationships that govern these morphological changes are now beginning to be understood and their molecular basis identified. The overall picture emerging is of a highly organized cell in which the rules established for cell division and morphogenesis in organisms such as yeast and mammalian cells do not necessarily apply. Therefore, understanding the developmental cell biology of the African trypanosome is providing insight into both fundamentally conserved and fundamentally different aspects of the organization of the eukaryotic cell
Outgassing and dimensional changes of polymer matrix composites in space
A thermal-vacuum outgassing model and test protocol for predicting outgassing times and dimensional changes for polymer matrix composites is described. Experimental results derived from a 'control' sample are used to provide the basis for analytical predictions to compare with the outgassing response of Long Duration Exposure Facility (LDEF) flight samples
AN EVALUATION OF ETHNICITY AND LINGUISTIC BACKGROUNDS AS WIC FOOD SELECTION DETERMINANTS
The federally funded Women, Infants, and Children (WIC) program issues redeemable food instruments (or vouchers) to low-income mothers and their small children who demonstrate nutritional need. Not all such food instruments are actually redeemed. Both ethnicity and home language preferences were found to be significantly correlated with individualsÂ’' WIC food instrument redemption likelihood. However, these correlations provided little indication that any food type (except cheese for Asians) is more or less culturally acceptable to any particular ethnic or language group. Regardless of ethnicity, persons who show English as their family language preference tend to have lower food instrument redemption rates than do those who prefer to speak any other language, at least among family members. This redemption rate disparity indicates that, to induce participants to follow dietary guidelines consistent with general public health goals, even a food assistance program, such as WIC, needs to employ some marketing techniques. Use of the English language should be a major consideration in segmenting WIC markets.Food Security and Poverty,
AN ILLUSTRATION OF THE NEED FOR AN INTERNATIONAL MARKETING PROFILE DATABASE: THE CASE OF EXPORTED U.S. APPLES
International Relations/Trade, Marketing,
Evidence for an interplay between cell cycle progression and the initiation of differentiation between life cycle forms of African trypanosomes
Successful transmission of the African trypanosome between the mammalian host blood-stream and the tsetse fly vector involves dramatic alterations in the parasite's morphology and biochemistry. This differentiation through to the tsetse midgut procyclic form is accompanied by re-entry into a proliferative cell cycle. Using a synchronous differentiation model and a variety of markers diagnostic for progress through both differentiation and the cell cycle, we have investigated the interplay between these two processes. Our results implicate a relationship between the trypanosome cell cycle position and the perception of the differentiation signal and demonstrate that irreversible commitment to the differentiation occurs rapidly after induction. Furthermore, we show that re-entry into the cell cycle in the differentiating population is synchronous, and that once initiated, progress through the differentiation pathway can be uncoupled from progress through the cell cycle
NASA-tricot - A lightweight radar reflective, knitted fabric
Fabric knitted on conventional knitting machines uses commercially available yarns, has high aerodynamic drag capability, and is relatively inexpensive. The two yarn components used are 15-denier nylon monofilament and aluminized Mylar tape
Lightweight inflatable material with low permeability
Material features combination of Mylar, for strength, and Saran, for impermeable qualities. Second lamination of Mylar prevents blocking, adds strength, and increases barrier rating. Different combinations of laminations produce variety of thicknesses and barrier ratings. Material can be metallized for increased barrier reliability and radar reflectivity, and can be treated with a heat-resistant coating
Disruption of the developmental programme of Trypanosoma brucei by genetic ablation of TbZFP1, a differentiation-enriched CCCH protein
The regulation of differentiation is particularly important in microbial eukaryotes that inhabit multiple environments. The parasite Trypanosoma brucei is an extreme example of this, requiring exquisite gene regulation during transmission from mammals to the tsetse fly vector. Unusually, trypanosomes rely almost exclusively on post-transcriptional mechanisms for regulated gene expression. Hence, RNA binding proteins are potentially of great significance in controlling stage-regulated processes. We have previously identified TbZFP1 as a trypanosome molecule transiently enriched during differentiation to tsetse midgut procyclic forms. This small protein (101 amino acids) contains the unusual CCCH zinc finger, an RNA binding motif. Here, we show that genetic ablation of TbZFP1 compromises repositioning of the mitochondrial genome, a specific event in the strictly regulated differentiation programme. Despite this, other events that occur both before and after this remain intact. Significantly, this phenotype correlates with the TbZFP1 expression profile during differentiation. This is the first genetic disruption of a developmental regulator in T. brucei. It demonstrates that programmed events in parasite development can be uncoupled at the molecular level. It also further supports the importance of CCCH proteins in key aspects of trypanosome cell function
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