A simple model of interactive pollutants

This study presents a model of two interactive pollutants in which the natural rate of regeneration of each pollutant is affected by the quantity of the other pollutant present in the atmosphere. The behavior of pollution accumulations in the natural unintervened system is characterized. With human intervention, it is shown that while a sustainable environment can be obtained, a deteriorating environment may also arise. There is a unique continuous boundary beyond which the environment is non-revitalizable.     

Investigation into the role of phosphatidylserine in modifying the susceptibility of human lymphocytes to secretory phospholipase A2 using cells deficient in the expression of scramblase

Normal human lymphocytes resisted the hydrolytic action of secretory phospholipase A₂ but became susceptible to the enzyme following treatment with a calcium ionophore, ionomycin. To test the hypothesis that this susceptibility requires exposure of the anionic lipid phosphatidylserine on the external face of the cell membrane, experiments were repeated with a human Burkitt's lymphoma cell line (Raji cells). In contrast to normal lymphocytes or S49 mouse lymphoma cells, most of the Raji cells (83%) did not translocate phosphatidylserine to the cell surface upon treatment with ionomycin. Those few that did display exposed phosphatidylserine were hydrolyzed immediately upon addition of phospholipase A₂. Interestingly, the remaining cells were also completely susceptible to the enzyme but were hydrolyzed at a slower rate and after a latency of about 100 s. In contradistinction to the defect in phosphatidylserine translocation, Raji cells did display other physical membrane changes upon ionomycin treatment that may be relevant to hydrolysis by phospholipase A₂. These changes were detected by merocyanine 540 and trimethylammonium diphenylhexatriene fluorescence and were common among normal lymphocytes, S49 cells, and Raji cells. The levels of these latter effects corresponded well with the relative rates of hydrolysis among the three cell lines. These results suggested that while phosphatidylserine enhances the rate of cell membrane hydrolysis by secretory phospholipase A₂, it is not an absolute requirement. Other physical properties such as membrane order contribute to the level of membrane susceptibility to the enzyme independent of phosphatidylserine.     

Protein tyrosine phosphatase-1C is rapidly phosphorylated in tyrosine in macrophages in response to colony stimulating factor-1.

An approximately 64-kDa cytoplasmic protein is rapidly phosphorylated in tyrosine in the response of macrophages to colony stimulating factor-1. To identify this protein, BAC1.2F5 macrophages were incubated with or without colony stimulating factor-1, the phosphotyrosine-containing portion of their cytosolic fractions subjected to size exclusion chromatography, and the 45-70-kDa fraction further fractionated by reverse phase high pressure liquid chromatography (RP-HPLC). Tryptic peptides of pooled RP-HPLC fractions from stimulated cells (containing the approximately 64-kDa protein and an approximately 54-kDa protein) and from unstimulated cells (containing the approximately 54-kDa protein alone), were sequenced directly. All seven readable sequences of 8 sequenceable peptides present uniquely in the stimulated fraction were present in the sequence of the src homology 2 domain-containing protein tyrosine phosphatase-1C (PTP-1C). The identity of the approximately 64-kDa protein was confirmed by Western blotting with an antibody raised to a PTP-1C peptide. The rapid, growth factor-induced tyrosine phosphorylation of PTP-1C suggests that it may be involved in very early events in growth factor signal transduction.     

Isolation and characterization of a galactose binding lectin with insulinomimetic activities. From the seeds of the bitter gourd Momordica charantia (Family Cucurbitaceae)

A galactose binding lectin was isolated from the seeds of the bitter gourd Momordica charantia by delipidation with petroleum ether, extraction with phosphate buffered saline, ammonium sulfate precipitation and affinity chromatography on lactogel. The lectin had a molecular weight of 124,000 and approximately 5% carbohydrate content. The molecular weights of the individual subunits were 37,000, 35,000 and 33,000. The lectin exhibited potent hemagglutinating activity. In addition, it demonstrated antilipolytic and lipogenic activities in isolated rat adipocytes although it did not possess intrinsic lipolytic activity. The antilipolytic activity was susceptible to destruction by heat, trypsin, chymotrypsin, glutathione and galactose, indicating that the integrity of the protein moiety, the disulfide linkages, and galactose, which is the sugar specifically bound by the lectin, all play an important role in interaction with the adipocyte leading to an expression of this insulin-like activity.     

Habitat and infauna prey availability for flatfishes in the northern Bering Sea

Yellowfin sole (Limanda aspera), northern rock sole (Lepidopsetta polyxystra), and Alaska plaice (Pleuronectes quadrituberculatus) are valuable flatfishes in the southeastern Bering Sea (EBS) bottom trawl fishery. The northern Bering Sea (NBS) is near their northern distribution limit. We conducted the first assessment of NBS habitat suitability for these benthivorous flatfishes from the perspective of prey availability in 2010. Benthic samples were collected at 12 trawl stations along a meridional transect extending from 60.5°N to 64.5°N east of St. Lawrence Island to characterize the prey environment. Stomach contents from the flatfishes were concomitantly collected to relate diets to prey fields. The diet compositions did not correspond spatially with the infauna communities. The flatfishes elected a prey group regardless of its relative availability. The spatial mismatch between diet and infauna compositions suggests that prey availability was high in the NBS. The flatfishes generally have versatile diets, but they were more selective of their prey here than in the EBS. The biomass and the abundance of the infauna along the transect were comparable with the EBS. Although niche overlap was high in the NBS, competition for food was likely lower than in the EBS because of the lower density of flatfish. The bottom temperatures in the NBS were in the same range as the EBS during the summer of 2010. The NBS appears to be suitable flatfish habitat at least during the summer ice-free period. The effects of climate warming on the prey environment and on the production and distribution of flatfish are complex and difficult to predict, but if the NBS were to shift over time toward milder winter conditions that more resemble the EBS, its suitability as flatfish habitat would presumably increase based on the present prey availability.     

Movement characteristics of ejaculated sperm from cynomolgus monkeys (Macaca fascicularis) analyzed by manual and automated computerized image analysis

Sperm motility is an important indicator of male reproductive function. An automated computerized system was used to measure the movement characteristics of cynomolgus monkey sperm. Swimming velocities were in good agreement with data derived from tracking sperm heads manually with a digitizer, but sperm counting by the system was erroneous. In some ejaculates, there were two subpopulations of sperm with different curvilinear velocities, linearities of swim-paths, and lateral movements of the heads.     

Iron intake of infants: the importance of infant cereals.

Since 1976 many baby foods have been reformulated and the iron used to fortify infant cereals has been changed to a more bioavailable form. Therefore, the dietary intake of iron by infants from 1 to 18 months of age was assessed in a longitudinal survey conducted in Toronto and Montreal between 1977 and 1979. Except in the 1st and 18th months the mean daily iron consumption of the infants was above that recommended in the Dietary Standard for Canada. The main source of this nutrient was infant cereals. Examination of the diets of the infants who did not have the recommended daily intake of iron showed that they did not consume sufficient amounts of infant cereals and other iron-rich foods. These results indicate that without such cereals it is difficult to provide infants with the amount of iron they need. Therefore, infants should receive these cereals during the first 2 years of life.