No abstract

Although campylobacters have been isolated from a wide range of animal hosts, the association between campylobacters isolated from humans and animals in the farm environment is unclear. We used flagellin gene typing and pulsed-field gel electrophoresis (PFGE) to investigate the genetic diversity among isolates from animals (cattle, sheep, and turkey) in farm environments and sporadic cases of campylobacteriosis in the same geographical area. Forty-eight combined fla types were seen among the 315 Campylobacter isolates studied. Six were found in isolates from all four hosts and represented 50% of the total number of isolates. Seventy-one different SmaI PFGE macrorestriction profiles (mrps) were observed, with 86% of isolates assigned to one of 29 different mrps. Fifty-seven isolates from diverse hosts, times, and sources had an identical SmaI mrp and combined fla type. Conversely, a number of genotypes were unique to a particular host. We provide molecular evidence which suggests a link between campylobacters in the farm environment with those causing disease in the community.

This unit describes procedures for fragmentation of IgG to the monovalent Fab fragment using papain digestion, and to the bivalent F(ab')(2) fragment by pepsin digestion. Alternative methods of fragmentation to F(ab')(2) include use of papain that is preactivated with cysteine and use of the enzyme ficin. These alternate methods are particularly useful for mouse IgG(1) antibodies.

SummaryAn increasing number of cell types, including peripheral blood mononuclear cells (PBMCs), have been demonstrated to release heat shock proteins (Hsps). In this paper we investigate further the hypothesis that Hsps are danger signals. PBMCs and Jurkat cells released Hsp70 (0·22 and 0·7 ng/10 6 cells, respectively) into medium over 24 h at 37 °°°° C. Release of Hsp70 was stimulated 10-fold by GroEL ( P < < < < 0·001) and more than threefold by lipopolysaccharide (LPS) ( P < < < < 0·001). Although Hsp60 could be detected in the medium of cells cultured at 37 °°°° C for 24 h, the low rates of release were due probably to cell damage. Significant release of Hsp60 was observed when Jurkat cells were exposed to GroEL (2·88 ng/10 6 cells) or LPS (1·40 ng/10 6 cells). The data are consistent with the hypothesis that Hsp70 and Hsp60 are part of a danger signalling cascade in response to bacterial infection.

The Southern Ocean is responsible for approximately 40% of oceanic carbon uptake through biological and physical processes. In the Southern Ocean, phytoplankton growth is limited by low iron (Fe) and light supply. Climate model projections for the Southern Ocean indicate that temperature, underwater irradiance and Fe supply are likely to change simultaneously in the future due to increasing anthropogenic carbon dioxide emissions. The individual effects of these environmental properties on phytoplankton physiology have been extensively researched, and culturing studies using Southern Ocean phytoplankton have shown that temperature and Fe will play a key role on setting growth under future conditions. To explore the potential responses of Southern Ocean phytoplankton to these environmental changes, we cultured the haptophyte Phaeocystis antarctica and the diatoms Chaetoceros flexuosus, Proboscia inermis, and Thalassiosira antarctica under two light and iron combinations and over a range of temperatures. Our study revealed that the thermal response curves of key Southern Ocean phytoplankton are diverse, with the highest growth rates measured at 5 • C (the annual temperature range at the isolation sites is currently 1-4 • C). Warming had species-specific effects on the photochemical efficiency of photosystem II (PSII; F v /F m), the functional absorption cross-section of PSII (σ PSII), carbon:nitrogen ratio and cellular Chlorophyll a concentrations. Iron availability increased species' ability to tolerate warmer conditions by increasing the upper limit for growth and subsequently increasing the thermal niche that each species inhabit.