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PERSPECTIVES AND OVERVIEWLocation and selection of an oviposition site is an essential part of the life history of all mosquito species. The remarkable number of oviposition be haviors range from the common, e.g. deposition of eggs on or near the water surface, to the unusual, e.g. egg brooding by adult females (73,74). The initiation of an ovipositional flight is linked with environmental factors, especially rainfall, relative humidity, temperature, and wind speed. The location and selection of an oviposition site involves visual, olfactory, and tactile responses.Since pathogen acquisition by vector mosquitoes usually requires the taking of at least one blood meal, disease transmission usually requires the comple tion of at least one oviposition cycle before pathogen transfer can occur with a subsequent blood meal. Oviposition is thus an important component of most mosquito-borne diseases.A tremendous amount has been written concerning mosquito oviposition. A large proportion of the studies have dealt with laboratory investigations on mosquito response to chemical and physical aspects of the oviposition site;relatively few field studies have been attempted. In this review we discuss general aspects of mosquito oviposition in nature, as well as the interplay 401 0066-4170/89/0101-0401$02.00 Annu. Rev. Entomol. 1989.34:401-421. Downloaded from arjournals.annualreviews.org by Yale University STERLING CHEMISTRY LIBRARY on 10/11/09. For personal use only. Quick links to online content Further ANNUAL REVIEWS 402 BENTLEY & DAY of chemical, physical, and physiological factors in oviposition site selection.Considering the number of published papers in the literature on oviposition, it is not possible for us to cite all of the important work. Rather, we attempt a broad survey of selected aspects of the chemical ecology and the oviposition behavior of gravid mosquitoes. OVIPOSITION BEHA VIOR IN NATUREThere are many similarities between mosquito host-seeking and oviposition behaviors. Both require complex integration of physical and chemical cues by searching mosquitoes. Long-range cues, probably involving vision, allow mosquitoes to identify different habitats (14) and specific host and oviposition site characteristics. As mosquitoes approach a host or an oviposition site other cues become important. For example, olfactory cues help mosquitoes to identify CO2 odor plumes from a host or volatile factors at the oviposition site. Once a host or an oviposition site has been identified, short-range cues become increasingly important. Short-range cues include temperature and chemical signals received by contact chemoreceptors. E1ectrophysiological studies have demonstrated that as the blood meal is digested in Aedes aegypti, neurons sensitive to host-produced cues, such as lactic acid, become less sensitive, while neurons sensitive to oviposition site attractants, such as methyl butyrate, become more sensitive (25).Certain mosquito species exhibit a great deal of specialization in both host and oviposition site selection, while ...

Polyoxazoline polymers with methyl (PMOZ), ethyl (PEOZ), and propyl (PPOZ) side chains were prepared by the living cationic polymerization method and purified by ion-exchange chromatography. The following properties of polyoxazoline (POZ) were measured: apparent hydrodynamic radius by aqueous size-exclusion chromatography, relative lipophilicity by reverse-phase chromatography, and viscosity by cone-plate viscometry. The PEOZ polymers of different molecular weights were first functionalized and then conjugated to model biomolecules such as bovine serum albumin, catalase, ribonuclease, uricase, and insulin. The conjugates of catalase, uricase, and ribonuclease were tested for in vitro activity using substrate-specific reaction methods. The conjugates of insulin were tested for glucose lowering activity by injection to naïve Sprague-Dawley rats. The conjugates of BSA were injected into New Zealand white rabbits and serum samples were collected periodically and tested for antibodies to BSA. The safety of POZ was also determined by acute and chronic dosing to rats. The results showed that linear polymers of POZ with molecular weights of 1 to 40 kDa can easily be made with polydispersity values below 1.10. Chromatography results showed that PMOZ and PEOZ have a hydrodynamic volume slightly lower than PEG; PEOZ is more lipophilic than PMOZ and PEG; and PEOZ is significantly less viscous than PEG especially at the higher molecular weights. When PEOZ was attached to the enzymes catalase, ribonuclease, and uricase, the in vitro activity of the resultant bioconjugates depended on the extent of protein modification. POZ conjugates of insulin lowered blood glucose levels for a period of 8 h when compared to 2 h for insulin alone. PEOZ, like PEG, was also able to successfully attenuate the immunogenic properties of BSA. The POZ polymers (10 and 20 kDa) are safe when administered intravenously to rats, and the maximum tolerated dose (MTD) was greater than 2 g/kg. Blood counts, serum chemistry, organ weights, and the histopathology of key organs were normal. These results conclude that POZ has the desired drug delivery properties for a new biopolymer.

An automatic segmentation technique has been developed and applied to two renal micro-computer tomography (CT) images. With the use of a 20-microm voxel resolution image, the arterial and venous trees were segmented for the rat renal vasculature, distinguishing resolving vessels down to 30 microm in radius. A higher resolution 4-microm voxel image of a renal vascular subtree, with vessel radial values down to 10 microm, was segmented. Strahler ordering was applied to each subtree using an iterative scheme developed to integrate information from the two segmented models to reconstruct the complete topology of the entire vascular tree. An error analysis of the assigned orders quantified the robustness of the ordering process for the full model. Radial, length, and connectivity data of the complete arterial and venous trees are reported by order. Substantial parallelism is observed between individual arteries and veins, and the ratio of parallel vessel radii is quantified via a power law. A strong correlation with Murray's Law was established, providing convincing evidence of the "minimum work" hypothesis. Results were compared with theoretical branch angle formulations, based on the principles of "minimum shear force," were inconclusive. Three-dimensional reconstructions of renal vascular trees collected are made freely available for further investigation into renal physiology and modeling studies.