Physiological and behavioural thermoregulation in bigeye tuna (Thunnus obesus).

Tuna are unique among teleost fishes in being thermoconserving. Vascular counter-current heat exchangers maintain body temperatures above ambient water temperature, thereby improving locomotor muscle efficiency, especially at burst speeds and when pursuing prey below the thermocline. Because tuna also occasionally swim rapidly in warm surface waters, it has been hypothesized that tuna thermoregulate to accommodate changing activity levels or ambient temperatures. But previous field experiments have been unable to demonstrate definitively short-latency, mammalian-type physiological thermoregulation. Here we show using telemetered data that free-ranging bigeye tuna (Thunnus obesus) can rapidly alter whole-body thermal conductivity by two orders of magnitude. The heat exchangers are disengaged to allow rapid warming as the tuna ascend from cold water into warmer surface waters, and are reactivated to conserve heat when they return into the depths. Combining physiological and behavioural thermoregulation expands the foraging space of bigeye tuna into otherwise prohibitively cold, deep water.

Alterations in mucosal content of colonic glycoconjugates in inflammatory bowel disease defined by monoclonal antibodies.

The presence of several glycoconjugates in colonic mucosa of patients with inflammatory bowel disease was assessed through indirect immunofluorescent staining using a collection of 23 monoclonal antibodies directed against human colonic mucin glycoproteins (anti-HCM MAbs). Intensity and distribution of staining by three anti-HCM MAbs were significantly altered in mucosa from patients with ulcerative colitis (UC) (n = 14) when compared with normal tissue (n = 15) and with tissue from patients with Crohn's disease as well as other inflammatory disorders (n = 15). Staining by anti-HCM MAb 17, which binds to colonic mucin glycoprotein species IV and V, was absent or diminished in 86% of samples from patients with active UC in contrast to 14% of normal and disease control specimens. Reduction in anti-HCM MAb 17 staining was less marked in mucosal biopsy specimens from patients with UC lacking acute inflammatory activity (n = 8). In contrast to the apparent loss of the MAb 17-defined epitopes, staining with anti-HCM MAbs 10 and 22 was enhanced in UC tissue compared with normal and disease controls. Increased staining with MAb 10 was present in 93% of samples from UC patients demonstrating active inflammation. Increased MAb 10 staining was not apparent in noninvolved mucosa from UC patients, indicating that increased expression of the specified epitope is related to the acute inflammatory process. In contrast, indirect immunofluorescent staining with MAb 22 was apparent in both involved (78%) and uninvolved (67%) UC mucosa in contrast to normal and disease controls (less than 12%). In addition, staining with several other anti-HCM MAbs (MAbs 3, 11, 15) was modestly and variably diminished (14%-28%) in UC, Crohn's disease, and other inflammatory disorders. These findings demonstrate the presence of alterations in mucosal content of specific glycoconjugate structures in association with UC. Inflammatory processes may also result in broad changes in glycoconjugate determinants generally.

Emergence of antigenic glycoprotein structures in ulcerative colitis detected through monoclonal antibodies.

The emergence of new glycoprotein structures in colonic mucosa from patients with ulcerative colitis (UC) was assessed through the development of monoclonal antibodies (MAbs). Hybridomas were prepared from mice immunized with mucin glycoproteins purified from UC colonic tissue. Supernatants of 11 fusion products among 1200 fusion products that were screened in a solid-phase binding assay differentially bound UC-derived colonic mucin glycoproteins relative to comparable preparations from normal or Crohn's colitis tissue. These hybridomas were double-cloned to yield MAbs designated as MAbs UC 1-11. Disease-related specificity of MAbs UC 1-11 was determined through assessment of binding to beads coated with mucin glycoproteins purified from individual samples of UC tissue (n = 15), normal tissue (n = 21), and Crohn's colitis tissue (n = 10). Monoclonal antibody UC 7, an MAb of immunoglobulin G2A subclass, showed differential binding in solid-phase assays to UC mucin glycoproteins, with a mean binding of 10,170 +/- 2740 cm per UC glycoprotein-coated bead versus 2300 +/- 1080 and 2470 +/- 1525 cpm for normal and Crohn's colitis-derived glycoproteins, respectively. Monoclonal antibody UC 11 showed similar differential binding to UC mucin glycoproteins (9860 +/- 680 cpm vs. 1770 +/- 420 cpm). Binding specificity in solid-phase assay was mirrored by colonic mucosal staining patterns assessed by indirect immunofluorescent staining. Monoclonal antibody UC 7 specifically stained colonic mucosa from 8 of 10 patients with active UC, none of the samples from 8 normal controls, and none of the samples from 11 disease controls (six with Crohn's colitis, five with other inflammatory disorders). Specific staining was present on both the epithelial surface and on cells scattered within the lamina propria. Staining by MAb UC 7 was also observed in 3 of 4 samples of proximal uninvolved mucosa from patients with left-sided ulcerative colitis and in 3 of 5 samples from UC patients without acute disease activity.

D-galactosyltransferase and its endogenous substrates in chick embryo fibroblasts transformed by Rous sarcoma virus.

UDP-D-galactose: 2-acetamido-2-deoxy-beta-D-glucopyranosyl 4-beta-D-galactosyltransferase (GalTase) activity was purified, from primary chick embryo fibroblast (CEF) transformed by a temperature-sensitive, Rous sarcoma virus mutant (CEF-RSV), by chromatography on an affinity resin prepared with monoclonal antibodies to GalTase. Cellular glycopeptides from CEF, as well as CEF-RSV, maintained at permissive (37 degrees) [CEF-RSF (37 degrees)] and nonpermissive temperatures (41 degrees) [CEF-RSV (41 degrees)], were solubilized and galactosylated in vitro by incubation with purified GalTase substrates, composed of at least six discrete complex glycopeptides having bi- to tetra-antennary structures. The glycopeptides isolated from transformed cells, CEF-RSV (37 degrees), included the six types observed in nontransformed cells, but demonstrated alterations in their relative amounts, including an increase in the content of a glycopeptide containing 3 mannose and 4 glucosamine residues. Furthermore, two additional complex-type glycopeptides were isolated from CEF- but demonstrated alterations in their relative amounts, including an increase in the content of a glycopeptide containing 3 mannose and 4 glucosamine residues. Furthermore, two additional complex type glycopeptides were isolated from CEF-RSV (37 degrees). These malignant transformation-related glycopeptides were partially characterized and found to represent tri- and tetra-antennary complex glycopeptides. Endogenous galactosylation appeared to have occurred in a branched, nonspecific manner in these transformed cell-derived glycopeptides. These findings indicate that transformed cells may contain a greater preponderance of more highly branched, complex oligosaccharides which are randomly galactosylated at nonreducing termini by cellular GalTase.

Development of anti-human colonic mucin monoclonal antibodies. Characterization of multiple colonic mucin species.

Structural relationships between colonic mucin species were assessed using a library of monoclonal antibodies (MAbs) directed against purified human colonic mucin (HCM). After immunization of mice with purified mucin from normal human colonic mucosa, 14% of 1,920 fusion products screened were positive for anti-HCM activity in a solid-phase assay. Patterns of selective binding by hybridomas to six discrete HCM species (I-VI) separated by DEAE-cellulose chromatography suggested the presence of both shared and species-specific antigenic determinants among HCM species I-VI. 23 anti-HCMs MAbs (7 IgM, 7 IgG1, and 9 IgG2) demonstrating a range of anti-HCM species specificities, were produced and used to study structural relationships between mucin species. Binding of various mucin species by individual anti-HCM MAbs was shown by competitive solid-phase radioimmunoassay to reflect the presence of identical epitopes on the different species. Adsorption of HCM species on a variety of affinity resins prepared with anti-HCM MAbs demonstrated that binding to multiple mucin species by a single MAb was related to intrinsic structural determinants. Four anti-HCM MAbs recognized protease-sensitive antigenic structures, which suggests that they may be directed to core HCM proteins. 12 of the anti-HCM MAbs were shown by solid-phase assay to recognize either complete (n = 5) or partial (n = 7) isolated colonic mucin oligosaccharide side chains of defined structure. Collectively, these data show the presence of both shared and unique antigenic structural determinants among colonic mucin species. Chromatographic heterogeneity of mucin glycoproteins seems to be related to the existence of biologically significant subclasses in the normal human colon.

Human colonic goblet cells. Demonstration of distinct subpopulations defined by mucin-specific monoclonal antibodies.

We studied glycoprotein content of human colonic goblet cells, using a library of monoclonal antibodies (MAbs) directed against purified human colonic mucin (HCM). Using indirect immunofluorescence (IIF), we found that 17 of 23 anti-HCM MAbs stained some or all goblet cells of normal human colonic mucosa. We observed a variety of cellular staining patterns, including (a) diffuse (homogeneous) staining of intracellular mucin, (b) speckled (inhomogeneous) staining of mucin droplets, (c) peripheral staining of intracellular droplets, (d) cytoplasmic staining of goblet cells, and (e) apical (luminal) surface staining. Staining patterns were not associated with particular HCM species. In addition to variable patterns of IIF within individual cells, anti-HCM MAbs varied in the proportion of goblet cells stained. Some MAbs stained all goblet cells, while others stained a limited number of goblet cells. Although each goblet cell contained more than one type mucin, HCM species III, and IV and V appeared to exist in mutually exclusive goblet cell populations and it was possible to define at least seven subpopulations of goblet cells in colonic mucosa by their content of various combinations of HCM species. Anti-HCM MAbs stained goblet cells from other sites within the gastrointestinal tract to a varying extent. Anti-HCM MAbs also showed extensive cross-reactivity with rodent, rabbit, and monkey colonic mucosa. However, several anti-HCM MAbs stained only human colonic mucosa. These data show that human colonic mucosa contains discrete subpopulations of goblet cells that produce distinctive combinations of specific mucin glycoprotein species.

Atomic emission and proton microprobe studies of the ion content of otoliths of chinook salmon aimed at recovering the temperature life history of individuals.

Atomic emission experiments on whole otoliths of the chinook salmon (Oncorhynchus tshawytcha) show that a statistically significant relationship exists between otolith ion content (Fr, Zn, Mn, Na, Sr, P), ambient temperature, body length and otolith weight amongst individuals maintained under controlled diet and water conditions. Direct proton microprobe studies confirm these results and suggest that it may be possible to recover the temperature life history of individual fishes from the otolith.