Overriding water table control on managed peatland greenhouse gas emissions.

Global peatlands store more carbon than is naturally present in the atmosphere1,2. However, many peatlands are under pressure from drainage-based agriculture, plantation development and fire, with the equivalent of around 3 per cent of all anthropogenic greenhouse gases emitted from drained peatland3-5. Efforts to curb such emissions are intensifying through the conservation of undrained peatlands and re-wetting of drained systems6. Here we report eddy covariance data for carbon dioxide from 16 locations and static chamber measurements for methane from 41 locations in the UK and Ireland. We combine these with published data from sites across all major peatland biomes. We find that the mean annual effective water table depth (WTDe; that is, the average depth of the aerated peat layer) overrides all other ecosystem- and management-related controls on greenhouse gas fluxes. We estimate that every 10 centimetres of reduction in WTDe could reduce the net warming impact of CO2 and CH4 emissions (100-year global warming potentials) by the equivalent of at least 3 tonnes of CO2 per hectare per year, until WTDe is less than 30 centimetres. Raising water levels further would continue to have a net cooling effect until WTDe is within 10 centimetres of the surface. Our results suggest that greenhouse gas emissions from peatlands drained for agriculture could be greatly reduced without necessarily halting their productive use. Halving WTDe in all drained agricultural peatlands, for example, could reduce emissions by the equivalent of over 1 per cent of global anthropogenic emissions.

Detection of Clostridium botulinum type C cells in the gastrointestinal tracts of Mozambique Tilapia (Oreochromis mossambicus) by polymerase chain reaction.

We established a method of directly detecting Clostridium botulinum type C cells, while minimizing spore detection, in the intestinal contents of Mozambique tilapia (Oreochromis mossambicus). This technique involved extraction of predominantly cellular DNA from tilapia intestinal tracts and used a polymerase chain reaction assay to detect presence of type C1 toxin gene. We consistently detected C. botulinum type C cells in tilapia gastrointestinal contents at a level of 7.5 x 104 cells per 0.25 g material or 1.9 x 103 cells. This technique is useful for determining prevalence of the potentially active organisms within a given population of fish and may be adapted to other types of C. botulinum and vertebrate populations as well.

In situ detection of the Clostridium botulinum type C1 toxin gene in wetland sediments with a nested PCR assay.

A nested PCR was developed for detection of the Clostridium botulinum type C1 toxin gene in sediments collected from wetlands where avian botulism outbreaks had or had not occurred. The C1 toxin gene was detected in 16 of 18 sites, demonstrating both the ubiquitous distribution of C. botulinum type C in wetland sediments and the sensitivity of the detection assay.

Golden hamster embryonic genome activation occurs at the two-cell stage: correlation with major developmental changes.

The earliest time of onset of embryonic genome activation in golden hamsters was investigated. The inhibition of transcription by alpha-amanitin (11 micrograms/ml) in cultured embryos resulted in a total arrest of development of early 2-cell embryos (26 hr post-egg activation); under similar conditions, immediate cleavage divisions of 1-, late 2-, 4-, and 8-cell embryos were not affected. Electrophoretic analysis of [35S]methionine-labeled embryonic proteins showed that alpha-amanitin treatment apparently inhibited transcription-dependent protein synthesis in early 2-cell and, to some extent, in late 2-cell when compared to 4-cell embryos. Analysis of total RNA synthesis, using [alpha 32P]-UTP or [32P]-orthophosphate, showed that there was a high proportion of radioactivity associated with the macromolecular fraction (RNA) at the early and late 2-cell stages and at the 4-cell stage compared to that at the 1-cell stage. These results indicate that the de novo synthesis of RNA, encoded by the embryonic genome, occurs at the 2-cell stage and that the second and subsequent cleavage divisions of hamster preimplantation embryos are dependent on new transcriptional activity. This initial activity of the embryonic genome in hamsters is coincident with several characteristic features of in vitro development such as a block to development, synthesis of major proteins, change in energy substrate preference, phosphate-inhibition of development and a requirement for amino acids.

Nucleotide sequence of a middle repetitive DNA from honey bees.

The nucleotide sequence of a 264-bp clone, pAfr3.4, which represents a related, tandemly arrayed, middle repetitive DNA family within various subspecies of the honey bee (Apis mellifera L.), has been determined.

Qualitative comparison of protein production at different stages of hamster preimplantation embryo development.

The developmental pattern of protein production in hamster preimplantation embryos was investigated as a preliminary to studying the regulation of gene expression. Optimal radiolabelling of embryonic proteins was achieved by culturing a minimum of 40 embryos in 50 microliters of Hamster Embryo Culture Medium-2 for 2 h with 10 microCi of freshly lyophilized [35S]methionine. Proteins synthesized in vitro by different stages of hamster preimplantation embryos were analysed by one- and two-dimensional polyacrylamide gel electrophoresis followed by autoradiography. There were striking changes in the protein profile following the first cleavage division and also lesser changes after the second cleavage division. There were no detectable qualitative changes in the protein profiles of 4-cell, 8-cell, morula and blastocyst stages although some quantitative difference existed between morula and blastocyst stages. These comparisons of protein profiles during different stages of embryo development indicate that in hamsters the onset of embryonic gene activation occurs during the 2-cell stage.

Heat stress induced enhancement of heat shock protein gene activity in the honey bee (Apis mellifera).

We employed in vitro translation of mRNA and product separation using SDS-PAGE to examine the heat-shock response of the worker honey bee. Increases in the levels of 6 translatable RNA populations were observed following heat stress. The greatest response was observed among bees aged 9 days. Slight levels of induction of 70 and 82 kDa heat shock proteins were evident among bees taken directly from the colony.

Presence of mitochondrial D-loop DNA in scrapie-infected brain preparations enriched for the prion protein.

The prion preparation has, in recent years, been the focal point of scrapie research. The inability to identify agent-specific nucleic acids in this sample has led to the formulation of the infectious protein or prion hypothesis. In this study, we analyzed three different prion protein-enriched preparations and found all to contain significant amounts of mitochondrial nucleic acid. Southern blot analyses indicated that they are enriched for a specific component of the mitochondrial genome, the single-stranded displacement loop fragment. Our results suggest that if mitochondrial nucleic acids are involved in scrapie infection, it is the displacement loop fragment that is specifically responsible.

A comparison of simultaneous longitudinal and radial recordings of anal canal pressures.

A new anal manometry perfusion catheter is described that offers the capability of simultaneous linear longitudinal pressure measurements. The authors studied 20 control subjects with this catheter and with a four-quadrant perfusion catheter. An asymmetry of basal, squeeze, and relaxation pressures was found. The highest basal pressures were in the middle of the anal canal, regardless of quadrant orientation. Using the radial perfusion catheter, the squeeze pressure profile was consistent with a double-loop external sphincter mechanism. Using the linear perfusion catheter, the internal sphincter relaxation pressures show a greater negative deflection at the proximal portions of the sphincter, which was not achieved at points distally in the same quadrant. This implies that during reflex relaxation, pressure is maintained in the distal anal canal so that patients remain continent during sensory sampling of rectal contents. The authors believe this is the first time this same-quadrant longitudinal asymmetry of relaxation has been shown with a single rectal balloon stimulus.

Evidence of mitochondrial involvement in scrapie infection.

Two cDNA libraries were constructed from brain membrane and cytoskeletal preparations purified from scrapie-infected hamster brains. Four recombinants strongly preferential to the scrapie cytoskeletal preparation were identified by the differential hybridization of 7,000 recombinants. These clones were not, however, preferential to total nucleic acids extracted from scrapie-infected hamster brains. DNA sequence analysis revealed all four clones to have significant sequence similarities to the mouse mitochondrial genome. This correlation led us to consider a mitochondrial association with scrapie infectivity. Brain mitochondria were purified by sucrose gradient density centrifugation and found to contain high infectivity. Removal of mitochondrial outer membranes by osmotic shock or digitonin treatment resulted in no detectable loss of titer.