Guiding cellular activity with polarized light

Actin, cytoskeleton protein forming microfilaments, play a crucial role in cellular motility. Here we show that exposure to very low levels of polarized light guide their orientation in‐vivo within the live cell. Using a simple model to describe the role of actin‐filament orientation in directional cellular motion, we demonstrate that the actin polymerization/depolymerization mechanism develops primarily along this direction and, under certain conditions, can lead to guidance of the cell movement. Our results also show a dose dependent increase in actin activity in direct correspondence to the level of laser irradiance. We found that total expression of Tau protein, which stabilize microtubules, was decreased by the irradiance, indicating that exposure to the light may change the activity of kinase, leading to increased cell activity.

     

Gluconeogenesis and the peroxisome

The interaction between hydroperoxides, cytochrome P450 and 8-anilino-1-naphthalenesulfonic acid (ANS) has been investigated. The addition of ANS to the cytochrome P450 solution did not effect the P450 Soret absorption peak or the reduced CO difference spectrum, suggesting that ANS may not bind to P450 heme directly. H2O2 or CuOOH alone did not effect ANS fluorescence and absorption spectra indicating that no detectable reaction occurs between hydroperoxide and ANS in the absence of P450. The reconstituted system of cytochrome P450, P450 reductase, lipid and NADPH did not mediate ANS metabolism. In the presence of P450, the addition of either H2O2 or CuOOH, however, leads to a decrease in ANS absorption around 258 nm and 350 nm indicating possible destruction of ANS. ANS destruction was confirmed with the disappearance of the ANS elution peak in the reverse phase HPLC profiles and with the changes in P450-bound ANS fluorescence intensity and the shift of max of ANS. Moreover , a very sensitive method to detect trace fluorescent products of ANS by thin layer chromatography has been developed based on the fact that ANS fluorescence is enhanced more than 1000-fold by the organic solvent butanol. A UV-sensitive fluorescent product was detected on thin layer chromatography profiles of the reaction mixtures. P450 was also observed to be modified by a fluorescent derivative of ANS, when the fluorescence was enhanced by butanol. These results also show that an organic compound which can not be metabolized by the reconstituted system of cytochrome P450 and NADPH-P450 reductase is metabolized by the reconstituted system of P450 and hydroperoxide, suggesting the activities of these two systems may not be completely comparable. (Mol Cell Biochem 167: 159-168, 1997)     

Increased gene expression of plasminogen activators and inhibitors in left ventricular hypertrophy

In the early stages of left ventricular hypertrophy (LVH) acute adaptive changes occur in the coronary vasculature as it remodels. Plasminogen activators (PAs) and inhibitors (PAIs) have the potential effects of proteolytic degradation that is relevant to tissue remodeling and angiogenesis. Our study focused on the possible roles of PAI-1, PAI-2, uPA and tPA in myocyte hypertrophy and angiogenesis in the early and late stages of pressure overload induced left ventricular hypertrophy (LVH). We divided seventeen adult swine, weighing 24.2 ± 6.5 kg, into four groups: control, sham-operated, early LVH and late heart failure LVH group. At surgery we placed a fixed constrictor on the ascending aorta immediately above the aortic valve. This increased LV systolic pressure from 133 ± 15 to 193 ± 24 mm Hg after the surgery. We subdivided the early group into groups of 3 animals each that we euthanized at 8, 24 and 72 h after operation and obtained heart samples for analysis. In the late heart failure group individual animals were euthanized at 55, 59, 62 and 72 days after the detection of congestive heart failure. We also obtained tissue samples from the control and sham-operated swine. Sections for histologic analysis were fixed in 10% buffered formalin. We isolated RNA, size fractionated it using 1% formaldehyde-agarose gel electrophoresis and then did Northern blots. The mRNAs from both PAI-1 and PAI-2 showed a remarkable increase at 8 and 24 h after acute aortic constriction and returned to control by 72 h. Regional differences showed that most of the increases were in the endocardium. Three animals in the late heart failure LVH group were determined to be in congestive heart failure at about 2 months after the onset of aortic constriction. In these animals PAI-1 and PAI-2 were increased in both the left and right ventricles but remained low in an animal of the same elevation in aortic pressure seen by the LV who did not have congestive failure. These data suggest that PA and PAI gene expressions change before morphologic changes occur in the early stages of developing LVH. Also at the time of onset of congestive heart failure this increased expression reappears. PAs and PA inhibitors mRNA levels vary in the different regions of the heart reflecting changing wall stresses. Thus, the PAs and PA inhibitors may play an important role in angiogenesis that occurs during the early stages of LVH. The increased expression in the late stage of LVH may reflect further changes in wall stresses since these animals also showed overt clinical signs of heart failure.     

Cancer risks in two large breast cancer families linked to BRCA2 on chromosome 13q12-13.

The penetrance of the BRCA2 gene on chromosome 13q12-13 has been estimated in two large, systematically ascertained, linked families, by use of a maximum-likelihood method to incorporate both cancer-incidence data and 13q marker typings in the families. The cumulative risk of breast cancer in female gene carriers was estimated to be 59.8% by age 50 years (95% confidence interval [95% CI] 25.9%-78.5%) and 79.5% by age 70 years (95% CI 28.9%-97.5%). The cumulative risk of breast cancer in male carriers was estimated to be 6.3% (95% CI 1.4%-25.6%) by age 70 years. There was no evidence of any risk difference between the two families. These results indicate that the lifetime breast cancer risk in BRCA2 carriers, for at least a subset of mutations, is comparable to that for BRCA1. A significant excess of ovarian cancer in gene carriers was observed (relative risk 17.69, based on three cases), but the absolute risk of ovarian cancer was less than that reported for BRCA1. Significant excesses of laryngeal cancer (relative risk 7.67, based on two possible carriers) and prostate cancer (relative risk 2.89, based on five possible carriers) were also observed. One case of ocular melanoma, as well as a second eye cancer of unspecified histology, occurred in obligate gene carriers.     

Trinucleotide Microsatellite Loci and Increased Heterozygosity in Cross-Species Applications in the Social Wasp, Polistes

Though microsatellite loci are usually found to be most polymorphic in the species in which they are first identified, we have found significant increases in polymorphisms in some cross-species applications. We present eight new trinucleotide microsatellite loci derived from two species of social wasps, Polistes annularis and Polistes bellicosus. We assessed the primers designed from these species and the degree of polymorphism in two additional species, P. dorsalis, which is very closely related to P. bellicosus, and P. dominulus, which is an Old World congener, thought to have diverged from New World Polistes over 80 million years ago. Cross-species applications for these microsatellite loci indicate that the priming sites from P. bellicosus loci are conserved in P. dorsalis and amplified similarly sized products with higher heterozygosities than the original species in two of three cases. A locus that was monomorphic in P. annularis had a heterozygosity of 1.0 in the distantly related P. dominulus. Cross-species applications of these loci indicated that alleles were generally of similar lengths in the new and original species when they retained their heterozygosity.     

Does immobilization of Thiobacillus ferrooxidans really decrease the effect of temperature on its activity?

It has been suggested that the influence of temperature on the activity of Thiobacillus ferrooxidans is decreased when the cells are immobilized. This is contrary to normal expectations and the work presented here indicates that it is not, in fact, the case. Experimental results are presented which show that the kinetics of Fe(II) oxidation by biofilms at 30°C are significantly faster than those at 20°C. Temperature, therefore, plays an important role in the activity of T. ferrooxidans, even in the immobilized form, and results indicate that it can also be used to control the level of biomass within the immobilized cell bioreactor.     

SHIPBOARD LINE TRANSECT SURVEYS OF CRABEATER SEAL ABUNDANCE IN THE PACK-ICE OFF EAST ANTARCTICA: EVALUATION OF ASSUMPTIONS

We examine the extent to which the assumptions underlying line transect sampling are satisfied in shipboard surveys of crabeater seals ( Lobodon carcinophaga ) hauled out on the Antarctic pack-ice. Measurement of the perpendicular distance of seal groups from the ship with an electronic inclinometer fitted to a rifle stock was unbiased. Crabeater seals showed little movement in response to the approaching ship. Movement away from the ship by seals close to the ship's track was partially responsible for a relative lack of sightings close to the transect-line, but otherwise had little effect on the sighting histogram. Minor deviations from the transect direction to avoid running over seals violated the assumption of uniform distribution of groups, and contributed to a relative lack in sightings close to (<40 m) the transect-line. We estimate that 5%-10% of seal groups close to the transect-line were not sighted by bridge observers prior to passing abeam of the ship, but most of these missed groups were likely to have been sighted some distance behind-abeam. Shipboard transects provided a biased sample of four environmental features known to be related to crabeater seal abundance because of logistical difficulties in the ship traversing along straight transects through thick ice. Calculation of transect length L from successive GPS locations was mildly sensitive to the frequency of locations. We provide analytical recommendations to reduce or eliminate the effect of assumption violation when present and hence minimize bias in abundance estimation.