Specific amplification of the 18S rRNA gene as a method to detect zebra mussel (Dreissena polymorpha) larvae in plankton samples

An important issue in the management of zebra mussel (Dreissena polymorpha) populations is early, rapid, and accurate detection of the planktonic larvae (veliger) of the zebra mussel. The goal of this study was to explore the feasibility of developing a molecular approach for the detection of zebra mussel larvae in diverse environments. In this study a Dreissena polymorpha-specific 18S ribosomal RNA gene targeted oligonucleotide primer (ZEB-715a) and Polymerase Chain Reaction (PCR) assay was developed and compared with cross-polarized microscopy as a means to detect zebra mussel veligers in plankton samples. The design of the zebra mussel-specific primer was facilitated by sequencing nearly the complete 18S rRNA gene from the zebra mussel and three other closely related freshwater Veneroids including the quagga mussel (D. bugensis), the dark false mussel (Mytilopsis leucophaeata), and the Asian freshwater clam (Corbicula fluminea). The specificity of the primer for the zebra mussel was empirically tested by using the primer as a direct probe in a blot hybridization format. A single veliger in a plankton sample could be detected by PCR using this approach. Veliger detection sensitivity using the PCR approach was estimated to be over 300 times more sensitive than cross-polarized light microscopy based techniques. Cross-polarized light microscopy and the PCR technique were used to identify the presence of zebra mussel larvae in plankton samples that were collected from a variety of natural and industrial water sources. Detection results (presence or absence) were generally consistent between the two methods. Although additional studies will be required before routine application of molecular based veliger detection technology is available, a long-term goal of this work is the application of molecular technology to the development of a field device for the routine detection and quantification of zebra mussel veligers.     

Carbonated water mediated preparation of poly(N-isopropylacrylamide) thermoresponsive gels and liquids

Carbonic acid solution was used a medium for the free radical polymerization synthesis of poly( N-isopropylacrylamide) (p-nipam) thermoresponsive polymer as an alternative to conventional inert gas purging. It was found that p-nipam cross-linked gels or linear liquids and p-nipam/dextran magnetite composite gels could be very rapidly prepared and large gels recovered intact from open air vessels. A porogen was necessary for high thermoresponse, and dextran use resulted in microporous composite gels that gave optimal thermal response at weight ratio of p-nipam:dextran of 4:1. Up to 82% weight loss was rapidly obtained upon warming above the lower critical solution temperature. Analysis of products was made by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and superconducting quantum interference device (SQUID). A simplified and efficient overall method for preparation of biomedical polymers is shown. A wider application of H2CO3 solution as a viable alternative media and to allow open air aqueous polymerizations of water soluble or hydrophilic monomers is indicated.     

Development of soil and vegetation climaxes in the Mount Kosciusko area,Australia

Summary Rates of development of alpine herbfield vegetation and alpine humus soils are studied in an area of fjaeldmark, on solifluction terraces, in the Mt. Kosciusko area of Australia.In relatively favourable sites, at the base of the solifluction terraces, the development from fjaeldmark to mature herbfield vegetation and soils can occur rapidly, within 40–50 years.Evidence is presented that much of the existing vegetation and soils at Kosciusko has developed from fjaeldmark by the successional processes described in this paper.

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Zusammenfassung Die Entwicklungsschnellheit der Vegetation einer Alpenwiese und eines alpinen Humus-Bodens wurden in einem Fjaeldmark-Gebiet, auf Solifluktions-Terrassen, in der Umgebung des Mt. Kosciusko, Australien, studiert. An verhaltnismäßig günstigen Stellen, am Fuße der Erdfluß-Terrassen, kann die Entwicklung von Fjaeldmark zur reifen Wiesenvegetation schnell vorsichgehen, innerhalb von 40–50 Jahren.Es wird angezeigt daß große Teile bestehender Vegetation und Boden beim Kosciusko durch den hier Beschriebenen Sukzessionsprozess aus Fjaeldmark entstanden sind.