Conversion of premalignant human cells to tumorigenic cells by methylmethane sulfonate and methylnitronitrosoguanidine

Nine human tumor cell lines derived from both epithelial and mesenchymal tumors exhibited either an anchorage-independent growth non-tumorigenic phenotype or an anchorage-independent tumorigenic phenotype. Transformed epithelial cell lines with the non-tumorigenic phenotype could be converted to a progressively growing tumor phenotype following treatment with either methylmethane sulfonate (MMS) or N-methyl-N-nitro-N-nitrosoguanidine (MNNG). In contrast, sarcoma derived cell lines with a non-tumorigenic phenotype could be converted to a progressively growing tumor phenotype only with MNNG. SV40 immortalized HET-1A non-tumorigenic phenotype cells could be converted to a progressively growing tumorigenic phenotype, infrequently, when treated with MNNG, but not MMS. Progressively growing tumors produced by either MMS or MNNG treated non-tumorigenic phenotypes exhibited metastatic potential in nude mice. Chemically treated HET-1A cells acquired the ability to produce tumor in mice but the tumor did not exhibit metastatic potential. In contrast, populations of tumorigenic cells were not rendered more biologically aggressive after treatment with either MMS or MNNG; i.e., the latency period for tumor development was not accelerated and the tumors did not exhibit metastatic potential. These results suggest that the biological effects of MMS and MNNG on non-tumorigenic, tumorigenic and immortalized cell lines are phenotype specific.Abbreviations AIG anchorage-independent growth - DMSO dimethyl sulfoxide - FBS fetal bovine serum - GM growth medium - MEM Eagle's minimum essential medium - MMS methylmethane sulfonate - MNNG N-Methyl-N-Nitro-N-Nitrosoguanidine - PDL population doubling - SCC squamous cell carcinoma     

Insulin resistance and decreased spexin in Indian Patients with Type 2 Diabetes Mellitus

Spexin is novel biomarker, which plays a potential role in glucose and lipid metabolisms. However, there was paucity of serum spexin levels in obesity and diabetes mellitus subjects. Hence the current study was aimed to find the relationship between the serum spexin levels in type 2 Diabetes mellitus (type 2 DM) with extrapolation of cardiovascular disease (CVD) risk. A cross-sectional study included 330 participants, subdivided as control (n=110), type 2 DM (n=110) and type 2 DM with CVD groups (n=110). HbA1c, insulin, lipid profile, spexin & leptin including blood pressure and body mass index were analyzed from all the participants. The serum spexin levels (ng/ml) were significantly decreased in type 2 DM (mean ± sd: 0.65 ± 0.03) and type 2 DM with CVD (0.48 ± 0.02) groups compared to the control (0.79 ± 0.03) group (p<0.001). The decreased spexin levels were observed in type 2 DM, and further more decreased in type 2 DM with CVD patients compared to controls indicating that spexin levels could be served as an early prediction of obesity-induced T2DM with CVD risk.     

Real-time imaging of the dynamics of secretory granules in growth cones

Secretory granules containing a hybrid protein consisting of the regulated secretory protein tissue plasminogen activator and an enhanced form of green fluorescent protein were tracked at high spatial resolution in growth cones of differentiated PC12 cells. Tracking shows that granules, unlike synaptic vesicles, generally are mobile in growth cones. Quantitative analysis of trajectories generated by granules revealed two dominant modes of motion: diffusive and directed. Diffusive motion was observed primarily in central and peripheral parts of growth cones, where most granules diffused two to four orders of magnitude more slowly than comparably sized spheres in dilute solution. Directed motion was observed primarily in proximal parts of growth cones, where a subset of granules underwent rapid, directed motion at average speeds comparable to those observed for granules in neurites. This high-resolution view of the dynamics of secretory granules in growth cones provides insight into granule organization and release at nerve terminals. In particular, the mobility of granules suggests that granules, unlike synaptic vesicles, are not tethered stably to cytoskeletal structures in nerve terminals. Moreover, the slow diffusive nature of this mobility suggests that secretory responses involving centrally distributed granules in growth cones will occur slowly, on a time scale of minutes or longer.     

The Citreoline Trogon as an Ecosystem Engineer1

The western Mexican endemic Citreoline Trogon (Trogon citreolus) builds its nest cavities in arboreal termitaria. We studied the reuse of these holes by other organisms after the trogons abandoned them in the tropical dry forest of western Mexico. Of the 24 cavities examined, 19 were occupied (5 by mammals and 14 by arthropods). We found two western Mexico endemic mammals (Marmosa canescens and Xenomys nelsoni) using these spaces. Our results suggest that the T. citreolus provides a critical role in creating necessary cavities for many organisms in tropical dry forests.     

Analysis of capsid formation of human polyomavirus JC (Tokyo-1 strain) by a eukaryotic expression system: splicing of late RNAs, translation and nuclear transport of major capsid protein VP1, and capsid assembly

Human polyomavirus JC (JCV) can encode the three capsid proteins VP1, VP2, and VP3, downstream of the agnoprotein in the late region. JCV virions are identified in the nucleus of infected cells. In this study, we have elucidated unique features of JCV capsid formation by using a eukaryotic expression system. Structures of JCV polycistronic late RNAs (M1 to M4 and possibly M5 and M6) generated by alternative splicing were determined. VP1 would be synthesized from M2 RNA, and VP2 and VP3 would be synthesized from M1 RNA. The presence of the open reading frame of the agnoprotein or the leader sequence (nucleotides 275 to 409) can decrease the expression level of VP1. VP1 was efficiently transported to the nucleus in the presence of VP2 and VP3 but distributed both in the cytoplasm and in the nucleus in their absence. Mutation analysis indicated that inefficiency in nuclear transport of VP1 is due to the unique structure in the N-terminal sequence, KRKGERK. Within the nucleus, VP1 was localized discretely and identified as speckles in the presence of VP2 and VP3 but distributed diffusely in their absence. These results suggest that VP1 was efficiently transported to the nucleus and localized in the discrete subnuclear regions, possibly with VP2 and VP3. By electron microscopy, recombinant virus particles were identified in the nucleus, and their intranuclear distribution was consistent with distribution of speckles. This system provides a useful model with which to understand JCV capsid formation and the structures and functions of the JCV capsid proteins.     

Evaluation of a fluorescent lectin-based staining technique for some acidophilic mining bacteria

A fluorescence-labeled wheat germ agglutinin staining technique (R. K. Sizemore et al., Appl. Environ. Microbiol. 56:2245-2247, 1990) was modified and found to be effective for staining gram-positive, acidophilic mining bacteria. Bacteria identified by others as being gram positive through 16S rRNA sequence analyses, yet clustering near the divergence of that group, stained weakly. Gram-negative bacteria did not stain. Background staining of environmental samples was negligible, and pyrite and soil particles in the samples did not interfere with the staining procedure.     

Size-related shifts in the habitat associations of young-of-the-year winter flounder (Pseudopleuronectes americanus): field observations and laboratory experiments with sediments and prey

Field surveys and laboratory studies were used to determine the role of substrata in habitat selection by young-of-the year winter flounder. A synoptic field survey of winter flounder and sediments in the Navesink River-Sandy Hook Bay estuarine system in New Jersey demonstrated that winter flounder distribution was related to sediment grain size. Analysis using a generalized additive model indicated that the probability of capturing 10-49 mm SL winter flounder was high on sediments with a mean grain diameter of /=40 mm SL) preferred coarse-grained sediments. Burying ability increased with size and all flounders avoided sediments that prevented burial. Subsequent laboratory experiments revealed that the presence of live prey (Mya arenaria) can over-ride sediment choice by winter flounder (50-68 mm SL) indicating the complexity of interrelated factors in habitat choice.     

Feeding behavior of newly settled winter flounder (Pseudopleuronectes americanus) on calanoid copepods

Field and laboratory investigations were conducted to examine feeding by newly settled winter flounder (Pseudopleuronectes americanus) on two co-occurring calanoid copepods, Eurytemora affinis and Acartia hudsonica. During the spring, these prey are present when winter flounder initiate their demersal lifestyle in estuaries of the northeastern United States. Epibenthic zooplankton were collected concurrently with winter flounder in the Navesink River estuary, NJ, in May 1998 and 1999. Although both calanoid species were in the estuary during the 2-year survey, E. affinis was consumed nearly to the exclusion of A. hudsonica by newly settled winter flounder. Annually, E. affinis and A. hudsonica had similar size distributions in field collections, indicating that species choice was not size selective. However, when preying on E. affinis, winter flounder preferred the larger sized organisms. In single species laboratory experiments, E. affinis and A. hudsonica were consumed equally by newly settled winter flounder (19-23 mm TL), but there were more strikes made toward E. affinis. Despite the lower catch efficiency, E. affinis was selected over A. hudsonica when the prey species were offered together in equal numbers. The selection for E. affinis over A. hudsonica by newly settled winter flounder may be the result of behavioral and/or morphological differences in the prey species.