High temporal variability of zooplankton,but only weak evidence for a near-bottom effect on composition and distribution in the deep Levantine Basin,eastern Mediterranean

Abundance and composition of the near-bottom zooplankton between 10 and 100 metres above the bottom (mab) were studied in the Levantine Basin, eastern Mediterranean, during four cruises of RV Meteor in June 1993, January 1998, April/May 1999 and October 2001. Copepoda made up 91% of all zooplankton caught. A strong dominance of one single species was observed on all cruises, with Lucicutia longiserrata reaching 50–90% of all Copepoda except in 1993, when Subeucalanus monachus was the most abundant species, with more than 90% of all Copepoda. The year 1993 was also exceptional in terms of total zooplankton abundance, being more than one order of magnitude higher than in the other years. Vertical differences in abundance and composition were small and did not indicate a near-bottom effect or a specialized benthopelagic zooplankton community in the layers sampled.     

The role of MHC class I heterodimer expression in mouse ankylosing enthesopathy

 Ankylosing enthesopathy (ANKENT) is a spontaneous mouse joint disease with strikingly similar pathology to human HLA-B27-associated enthesopathies such as ankylosing spondylitis. In C57Bl/10 mice, transgenic HLA-B^*2702 as well as H2 genes have been shown to be relative risk factors for ANKENT. To investigate the role of major histocompatibility complex (MHC) class I expression in disease pathogenesis, ANKENT occurrence was compared among β₂-microglobulin (β₂m) knockout littermates with or without transgenes for HLA-B^*2702 and human β₂m. In the knockout phenotype lacking β₂m, ANKENT occurrence is significantly reduced (P = 0.016). In the absence of β₂m, B^*2702 is not detected on the cell membrane, nor does it increase the risk for ANKENT. This means that the previous finding that HLA-B^*2702 increases susceptibility to ANKENT in C57Bl/10 mice cannot be ascribed to a transgene insertion effect. Rather, in order to increase disease susceptibility, B^*2702 must be coexpressed with mouse β₂m (mo-β₂m). In contrast, when HLA-B^*2702 is expressed with β₂m of human origin, disease susceptibility is not affected. Thus, both H2^b-derived class I heterodimers and HLA-B^*2702/mo-β₂m heterodimers contribute to ANKENT susceptibility.     

Colorectal Cancers Mimic Structural Organization of Normal Colonic Crypts

Colonic crypts are stereotypical structures with distinct stem cell, proliferating, and differentiating compartments. Colorectal cancers derive from colonic crypt epithelia but, in contrast, form morphologically disarrayed glands. In this study, we investigated to which extent colorectal cancers phenocopy colonic crypt architecture and thus preserve structural organization of the normal intestinal epithelium. A subset of colon cancers showed crypt-like compartments with high WNT activity and nuclear β-Catenin at the leading tumor edge, adjacent proliferation, and enhanced Cytokeratin 20 expression in most differentiated tumor epithelia of the tumor center. This architecture strongly depended on growth conditions, and was fully reproducible in mouse xenografts of cultured and primary colon cancer cells. Full crypt-like organization was associated with low tumor grade and was an independent prognostic marker of better survival in a collection of 221 colorectal cancers. Our findings suggest that full activation of preserved intestinal morphogenetic programs in colon cancer requires in vivo growth environments. Furthermore, crypt-like architecture was linked with less aggressive tumor biology, and may be useful to improve current colon cancer grading schemes.     

In situ nick translation of metaphase chromosomes with biotin-labeled d-UTP

Summary Conditioned culture medium from Daudi cells was used as a source of soluble H-Y antigen. Concentrated culture medium was labeled with ¹²⁵I and then fractionated by gel filtration. Column fractions were assayed for the presence of H-Y antigen by urease-ELISA. H-Y antigen-containing fractions were then pooled and subjected to an improved immunoprecipitation protocol. Three predominant H-Y antigenic proteins were identified with estimated molecular weights of above 200,000, 50,000, and 20,000.