Immunohistochemical demonstration of villin in the normal human pancreas and in chronic pancreatitis

Human pancreatic tissue was investigated by immunohistochemistry using a polyclonal antibody against the actin binding protein villin, which participates in the formation of actin filament bundles in the microvilli. In cells of the different parts of the pancreatic duct system as well as in the acinar cells villin immunoreactivity was located mainly at the apical cell surface. This was confirmed by the ultrastructural demonstration of microvilli on the surface of duct and acinar cells, which exhibited the typical actin bundles. In chronic pancreatitis the staining for villin in duct-like structures of degenerative pancreatic tissue was irregular or even absent. This correlated with the electron microscopic observation of duct-like structures known as tubular complexes composed of cells devoid of microvilli at the apical cell surface. At the light microscopical level degenerative structures without lumen and of unknown origin showed a strong staining for villin at their basal cell surface.     

Artemether Does Not Turn α Cells into β Cells

1. Download high-res image (299KB)
2. Download full-size image

     

Association patterns of bottlenose dolphins (Tursiops truncatus) in Bahía San Antonio,Argentina

This study aims to investigate the association patterns of a small and resident population of bottlenose dolphins (Tursiops truncatus) in Bahía San Antonio (Argentina), and assess any seasonal variation in view of the reported seasonal variation in the population's grouping behavior. The estimation of social differentiation (S) was 0.29 (SE = 0.08), suggesting a homogenous society. The half‐weight index (HWI) averaged 0.23 (± 0.06), with evidence of long‐term preferred associations. However, data showed seasonal variation in the association patterns. In winter, when large groups were reported in this population, HWI values averaged 0.30 (± 0.09) with no indication of preferred or avoided associations. However, during summer, when group size was generally small, HWI values averaged 0.14 (± 0.07), with an indication of preferred/avoided associations. This study indicates that the social structure of the bottlenose dolphins in Bahía San Antonio seems relatively homogenous and flexible over time, with the formation of a random social network at times when large aggregations are formed, and a more disconnected network made up of strongly connected components when the cost of grouping is high.     

Hidden in the Arabian Mountains: Multilocus phylogeny reveals cryptic diversity in the endemic Omanosaura lizards

An increase in studies in the Hajar Mountains from the southeastern Arabian Peninsula has revealed a high richness of endemic evolutionary lineages with many cryptic taxa. Omanosaura is the only lacertid lizard genus endemic to the Hajar Mountains, with two species O. cyanura and O. jayakari distributed throughout this mountain range. The phylogenetic relationships and genetic diversity between and within these species have been poorly studied. In this study, we collected mitochondrial (12S, cytb, and nd4) and nuclear (cmos and mc1r) sequences for 25 specimens of Omanosaura, including 15 individuals of O. jayakari and 10 of O. cyanura. We performed phylogenetic analyses based on network reconstruction, maximum likelihood and Bayesian inference to estimate the relationships and intraspecific genetic diversity of these species. We estimated the time of divergence between the two species in the Miocene, around 8.5 million years ago. Omanosaura jayakari shows little genetic diversity, while O. cyanura presents two differentiated lineages. These are reciprocally monophyletic at mitochondrial and nuclear genes and present a high genetic distance between them. These two lineages are associated with the geographic features of the Hajar Mountains, with one lineage distributed in the northernmost part of the Hajar Mountains and the other in the rest of the western Hajars, the Jebel Akhdar, and the eastern Hajars. This geographic relationship has been recovered previously in other reptile taxa and is generally associated with high levels of local genetic diversity. Our results suggest the existence of cryptic diversity within O. cyanura and support a general biogeographic pattern of high diversity and endemism in the northern Hajar Mountains that certainly deserves additional research in the future.     

Isolation and characterization of lectins and lectin-alliinase complexes from bulbs of garlic (Allium sativum) and ramsons (Allium ursinum)

A procedure developed to separate the homodimeric and heterodimeric mannose-binding lectins from bulbs of garlic (Allium sativum L.) and ramsons (Allium ursinum L.) also enabled the isolation of stable lectin-alliinase complexes. Characterization of the individual lectins indicated that, in spite of their different molecular structure, the homomeric and heteromeric lectins resemble each other reasonably well with respect to their agglutination properties and carbohydrate-binding specificity. However, a detailed analysis of the lectin-alliinase complexes from garlic and ramsons bulbs demonstrated that only the heterodimeric lectins are capable of binding to the glycan chains of the alliinase molecules (EC 4.4.1.4). Moreover, it appears that only a subpopulation of the alliinase molecules is involved in the formation of lectin-alliinase complexes and that the complexed alliinase contains more glycan chains than the free enzyme. Finally, some arguments are given that the lectin-alliinase complexes do not occur in vivo but are formed in vitro after homogenization of the tissue. This revised version was published online in November 2006 with corrections to the Cover Date.     

Isolation,characterization and molecular cloning of the mannose-binding lectins from leaves and roots of garlic (Allium sativum L.)

Two novel lectins were isolated from roots and leaves of garlic. Characterization of the purified proteins indicated that the leaf lectin ASAL is a dimer of two identical subunits of 12 kDa, which closely resembles the leaf lectins from onion, leek and shallot with respect to its molecular structure and agglutination activity. In contrast, the root lectin ASARI, which is a dimer of subunits of 15 kDa, strongly differs from the leaf lectin with respect to its agglutination activity. cDNA cloning of the leaf and root lectins revealed that the deduced amino acid sequences of ASAL and ASARI are virtually identical. Since both lectins have identical N-terminal sequences the larger Mr of the ASARI subunits implies that the root lectin has an extra sequence at its C-terminus. These results not only demonstrate that virtually identical precursor polypeptides are differently processed at their C-terminus in roots and leaves but also indicate that differential processing yields mature lectins with strongly different biological activities. Further screening of the cDNA library for garlic roots also yielded a cDNA clone encoding a protein composed of two tandemly arrayed lectin domains. Since the presumed two-domain root lectin has not been isolated yet, its possible relationship to the previously described two-domain bulb lectin could not be studied at the protein level.     

Isolation,characterization and molecular cloning of a leaf-specific lectin from ramsons (Allium ursinum L.).

Lectins were isolated from roots and leaves of ramsons and compared to the previously described bulb lectins. Biochemical analyses indicated that the root lectins AUAIr and AUAIIr are identical to the bulb lectins AUAI and AUAII, whereas the leaf lectin AUAL has no counterpart in the bulbs. cDNA cloning confirmed that the leaf lectin differs from the bulb lectins. Northern blot analysis further indicated that the leaf lectin is tissue-specifically expressed. Sequence comparisons revealed that the ramsons leaf lectin differs considerably from the leaf lectins of garlic, leek, onion and shallot.     

Ya baramb tenga

Ya baramb tenga (Our Ancestors' Earth:. Mossi Village in Burkina Faso). 1997. 47 minutes, color. video by Beate Engelbrecht. For more information contact the Institut für den Wissenschaftlichen Film, Nonnenstieg 72, 37075 Göttingen, Germany.