Activation of MAP kinases in growth responsive pancreatic cancer cells.

The implication of MAP kinases in the proliferation control of pancreatic cancer cells is still unknown. This study was undertaken to examine the contribution of the p44/p42 and p38 MAP kinases in the mitogenic response to epidermal growth factor (EGF) and bombesin in human pancreatic cancer cells, MIA PaCa-2 and PANC-1. Data indicate that EGF and bombesin stimulated growth of both cell lines. In MIA PaCa-2 cells, EGF and bombesin stimulated the in gel activation of p38 while p44/p42 kinases exhibited high basal activity and no response to stimuli. Growth and p38 activation were inhibited by genistein, wortmannin, PD98059 and SB203580, specific inhibitors of tyrosine kinase, phosphatidylinositol 3-kinase, MEK-1 and p38 kinases, respectively. In PANC-1 cells, EGF and bombesin stimulated p42 in gel activation; p44 remained highly activated and unresponsive to stimuli and p38 did not respond. Stimulated growth and p42 activation were inhibited by genistein, wortmannin and PD98059. Estimation of MAPK activities with a specific anti-active MAP kinase antibody indicated, however, that EGF increased the intensity of the bands corresponding to p42 and p44 MAP kinases in both cell lines, indicating that the mitogenic factor can regulate MAP kinase activity. Data also pointed out that ATP is sufficient to increase MAP kinase activity within the in gel assay technique and may thus explain the discrepancies existing between the in gel assay data and those obtained with the anti-active MAP kinase antibody.     

MULTIPLE MODES OF SPECIATION INVOLVED IN THE PARALLEL EVOLUTION OF SYMPATRIC MORPHOTYPES OF LAKE WHITEFISH (COREGONUS CLUPEAFORMIS,SALMONIDAE)

We performed a phylogenetic analysis of mtDNA variation among seven sympatric pairs of dwarf and normal morphotypes of whitefish from northern Québec and the St. John River drainage to address three questions relevant to understanding their radiation. Are all sympatric pairs reproductively isolated? Do phylogenetic analyses confirm that sympatric whitefish morphotypes found in eastern North America represent the outcome of polyphyletic evolutionary events? If so, did all sympatric pairs from the St. John River drainage originate from the same scenario of allopatric divergence and secondary contact? The hypothesis of genetic differentiation was supported for all sympatric pairs from the St. John River drainage, whereas lack of mtDNA diversity precluded any test of reproductive isolation for northern Québec populations. Patterns of mtDNA variation confirmed that dwarf and normal morphotypes evolved in parallel among independent, yet closely related, lineages, thus providing indirect evidence for the role of natural selection in promoting phenotypic radiation in whitefish. Patterns of mtDNA diversity among sympatric pairs of the St. John River indicated a complex picture of whitefish evolution that implied sympatric divergence and multiple allopatric divergence/secondary contact events on a small geographic scale. These results suggests that ecological opportunities, namely trophic niche availability, may promote population divergence in whitefish.     

Dynamics of pancreatic tissue cells in the rat exposed to long-term caerulein treatment. 2. Comparative analysis of the various cell types and their growth

This study was undertaken to evaluate the effects of caerulein, a CCK analog, on the different cell populations of the pancreatic tissue and their respective turnover. Rats received saline or caerulein subcutaneously and 3H-thymidine intraperitoneally three times a day for 4 days. They were sacrificed immediately after termination of treatment and 2, 15 and 50 days later. With age, the proportion of acinar cells decreased significantly whereas those of the ductal and interstitial cells increased. Although caerulein induced preferential acinar cell growth, it did not modify the proportion of this cell population with regard to the other cells. However, at specific times after termination of treatment, caerulein induced modifications in the ductal, endothelial and interstitial cell populations. The growth promoting effect of caerulein was evident from the specific increases in total DNA content and DNA synthesis. The labeling indices indicate that all cell populations except the endocrine system were stimulated to grow in response to caerulein. Furthermore, all new cells remained for at least 50 days after termination of treatment. These data indicate that caerulein induced uniform growth of the pancreatic tissue during intensive treatment. The normal growth rate of these stimulated cells was, however, arrested for the following 50 days while that of the control group cell population proceeded normally.     

The Genomic Basis of Color Pattern Polymorphism in the Harlequin Ladybird

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Establishment and immunocharacterization of an immortalized pancreatic cell line derived from the H-2Kb-tsA58 transgenic mouse

Summary This study describes the establishment and characterization of an immortalized cell line derived from the pancreas of an adult H-2K^b-tsA58 transgenic mouse. These cells, designated IMPAN for IMmortalized PANcreatic cells, displayed a cobblestone appearance typical of confluent epithelial cells and a distinct polarity in the organization of their cytoplasmic organelles. Immunocytochemical studies revealed that all IMPAN cells stained positively for a wide range of markers characteristic of pancreatic acinar cells, namely the secretory products α-amylase, chymotrypsinogen, DNAse, the lectinlike secretory protein PAP (pancreatitis associated protein), and the zymogen granule membrane proteins GP-2 and gp300. They also stained positively for carbonic anhydrase II and cytokeratin 19, two proteins characteristic of pancreatic duct cells, as well as for rab3A, a small GTP-binding protein specifically localized in pancreatic islet cells. No reactivity was ever obtained with insulin antibodies. Taken together, these results show that the IMPAN cells exhibit a phenotype comparable to exocrine pancreatic acinar cells. However the expression of some proteins more specific to duct and islet cells make them similar to in vivo or in vitro growing acinar cells. The cell line should be a valuable model to study the mechanisms of growth, differentiation, and transformation of the exocrine pancreatic acinar cell.     

Effect of somatocrinin and a somatostatin antiserum on duodenal and gastric growth in the rat

This study examines the effects of somatocrinin (GRF) and somatostatin antiserum (ASS), jointly and separately on gastric and duodenal growth. 24-day-old rats received twice daily SC injections of saline or GRF (4 and 20 micrograms X kg-1) for 14 days. ASS was given IP every 2 days. Alone, GRF increased gastric fundus weight concomitantly with DNA, RNA and protein contents producing hyperplasia and hypertrophy within this gland. Alone, ASS increased RNA and protein cellular concentrations. Joint ASS and GRF treatment stabilized the weight and protein content of the fundus, while reducing RNA contents as well as RNA and protein concentrations. GRF alone caused significant increments in duodenal weight and protein content suggesting cellular hypertrophy. Growth hormone, gastrin, cholecystokinin and secretin may be considered as putative mediators of these trophic effects.     

Polyamines and pancreatic growth induced by caerulein

Activation of polyamine metabolism may be important to initiation of pancreatic cell growth. We are reporting that such activation did occur during pancreatic growth initiation by caerulein, a cholecystokinin analog. Maximal increases in total putrescine (319%), spermidine (63%) and spermine (50%) were observed 12, 96 and 96 hr respectively after the beginning of the caerulein treatment. This time period coincides with pancreatic hypertrophy and hyperplasia as characterized by increased cell mass and DNA content. Rates of pancreatic weight and DNA content increases were significantly correlated with total spermidine and spermine contents. These data suggest that polyamine biosynthesis is closely associated with pancreatic growth.     

The chromosomes of the Canadian Beaver Castor canadensis.

A chromosome analysis of 24 Canadian beavers, Castor canadensis Kuhl (12 males and 12 females), captured in Laurentides Park, Qébec, has been performed from preparations of blood lymphocyte and skin cultures. The chromosome number was found to be 2n = 40. Measurements were made to determine relative lengths and arm ratios of chromosomes, which are metacentric or submetacentric. Results are in agreement with those already published regarding the chromosome number, but differ in the identification of the X chromosome, and in the morphology of the Y and some autosomes. C- ad G-banding techniques allowed the precise identification of individual chromosome pairs. A detailed idiogram of G-bands is presented.     

Relation between filter paper activity and saccharifying ability of a Trichoderma cellulase system

Summary Tests made to study the relation between filter paper activity and actual saccharifying ability of Trichoderma cellulases show that 30 IU/g of cellulose were sufficient to achieve over 80% hydrolysis of a 25 g/L cellulose suspension in 24 h. With the same enzyme/substrate ratio, but double the concentration of substrate, about 60% hydrolysis was achieved. End- product inhibition is one factor which seriously limits the degree of hydrolysis and therefore the concentration of sugars achievable by enzymatic hydrolysis at high levels of substrate concentration or enzyme/substrate ratio.