Die Anwendung von molekulargenetischen Techniken in der Neurochemie

Research in molecular neurobiology has recently entered a new phase of rapid development as a result of the application of the techniques of molecular genetics. This is illustrated by recent work on the electric ray (Torpedo marmorata and T. californica), whose electric organ is a rich source of cholinergic synapses. Other examples from recent literature of the application of the recombinant DNA technique to the mammalian central nervous system are given and possible future developments are discussed.     

The electromotor system of Torpedo

The electric organ of Torpedo, besides providing abundant amounts of cholinoceptive post-synaptic membrane for the isolation of the acetylcholine receptor protein, is a rich source of cholinergic nerve terminals. Using perfused, innervated tissue blocks from which synaptic vesicles in different functional states can be isolated, much information can be obtained about synaptic-vesicle dynamics. So far this is consistent with the view that the synaptic vesicles are the source of transmitter released on stimulation and that uptake of newly synthesized transmitter by the vesicles is dependent on their having discharged their previous charge of transmitter in at least one cycle of exo- and endocytosis. Studies of the protein composition of the vesicle membrane, especially when combined with similar information about the external presynaptic membrane, purified samples of which are now available from synaptosome (T-sac) preparations, promise to throw new light on the molecular mechanism underlying vesicle exo-/endocytosis.     

Stay and defend or leave early: Policy problems and experiences during the 2003 Victorian bushfires

Australian state and territory fire authorities advise residents to make a decision to prepare, stay and defend their properties from bushfires or leave well before the fire arrives in their area. The ‘Stay and defend or leave early’ policy is underpinned by strong evidence that well-prepared houses can be successfully defended and that late evacuation is a dangerous strategy. This paper presents the results of a study of the policy's implementation during the 2003 bushfires in North East Victoria and East Gippsland. Results suggest that despite high levels of awareness and support for the policy, there is some confusion over what it means to ‘stay and defend’ and ‘leave early’.     

Molecular prenatal diagnosis: the impact of modern technologies

Originally prenatal diagnosis was confined to the diagnosis of metabolic disorders and depended on assaying enzyme levels in amniotic fluid. With the development of recombinant DNA technology, molecular diagnosis became possible for some genetic conditions late in the 1970s. Here we briefly review the history of molecular prenatal diagnostic testing, using Duchenne muscular dystrophy as an example, and describe how over the last 30 years we have moved from offering testing to a few affected individuals using techniques, such as Southern blotting to identify deletions, to more rapid and accurate PCR-based testing which identifies the precise change in dystrophin for a greater number of families. We discuss the potential for safer, earlier prenatal genetic diagnosis using cell free fetal DNA in maternal blood before concluding by speculating on how more recent techniques, such as next generation sequencing, might further impact on the potential for molecular prenatal testing. Progress is not without its challenges, and as cytogenetics and molecular genetics begin to unite into one, we foresee the main challenge will not be in identifying the genetic change, but rather in interpreting its significance, particularly in the prenatal setting where we frequently have no phenotype on which to base interpretation. Copyright © 2010 John Wiley & Sons, Ltd.     

Interactions between Sitka spruce, the green spruce aphid, sulphur dioxide pollution and drought

Sitka spruce trees, with and without the aphid Elatobium abietinum and/or drought treatment, were subjected to 25 nl litre(-1) of sulphur dioxide over a 2-month period. Aphids became three times as abundant on the fumigated trees if they were well watered and twice as abundant on trees from which water was withheld, compared with unfumigated controls. Growth parameters of the trees were little affected by pollution alone, but were substantially reduced by either aphids or drought. There was a significant interaction between SO(2) and aphids in a further reduction of both leader extension and root weight. Root weight was also reduced by 24% more than expected from the additive effects of the combined SO(2) and drought treatment.     

Responses to ozone of insects feeding on a crop and a weed species

The influence of ozone on insect herbivore growth and population development was investigated. Fumigation of both pea (Pisum sativum L.) and dock (Rumex obtusifolius L.) at a range of O(3) concentrations between 21-206 nl litre(-1) produced changes in mean relative growth rates of the aphids Acyrthosiphon pisum Harris and Aphis rumicis L. of between 24 and -6% relative to controls. However, there was no evidence of a dose-related response to O(3) fumigation and no clear differences in aphid response when fumigated with the plant on prefumigated or previously unfumigated plant material. It is suggested that this may, in part, be due to the presence of NO contamination during O(3) fumigation. However, the MRGR of dock aphids was found to be greater on new compared to old leaves as well as the increase on the new growth and decrease on the old growth of fumigated plants relative to unfumigated controls. The size of egg batches of the chrysomelid beetle Gastrophysa viridula Degeer were found to be larger, survival and productivity of larvae was higher, and the food consumption lower on R. obtusifolius fumigated with 70 nl litre(-1) O(3) compared with unfumigated controls. This meant that these beetle larvae consumed less leaf area per mg of production on fumigated leaves probably because of their better nutritional quality and/or reduced leaf defences. However, the rate of development of larvae was similar on fumigated and control plants.     

GROUND WATER REPLENISHMENT FROM RIVERFLOW1

ABSTRACT: Ground water contours and gradients were determined within and adjacent to a gravelly riverbed with about 100 m active channel width and about 800 m flood plain width during low flow, making use of about 60 shallow dug wells and one deeper cased well Ground water slopes away from the riverbed to the south and slopes to the riverbed from the north. Replenishment of ground water to the south is past a “shell,” a zone of low permeability at the margin of and below the riverbed, (1) into a shallow aquifer from “sideway-spill-over” and (2) into an underlying aquifer that is seemingly confined by the “shell.” Seepage from river channels to underflow takes place all along channel lengths except below riffles where the flow direction is reversed. Half the seepage to underflow was lost to ground water replenishment Underflow seems to constitute merely a few percent of total riverflow but makes a disproportionate contribution to ground water replenishment.