Active T-cell receptor genes have intron deoxyribonuclease hypersensitive sites

The T-cell receptor beta-chain gene has a nuclease hypersensitive site in several kinds of T cells, which does not appear in B cells expressing immunoglobulins. Conversely, the kappa immunoglobulin gene shows a known hypersensitive site at its enhancer element in B cells, as expected, but this site is absent in T cells. As is the case with immunoglobulin genes, the T-cell receptor site lies within the gene, in the intron separating joining and constant region segments. These nuclease hypersensitive DNA configurations in the introns of active T-cell receptor and immunoglobulin genes may arise from control elements that share ancestry but have diverged to the extent that each normally acts only in lymphoid cells which use the proximal gene product.     

Incipient space weathering observed on the surface of Itokawa dust particles

The reflectance spectra of the most abundant meteorites, ordinary chondrites, are different from those of the abundant S-type (mnemonic for siliceous) asteroids. This discrepancy has been thought to be due to space weathering, which is an alteration of the surfaces of airless bodies exposed to the space environment. Here we report evidence of space weathering on particles returned from the S-type asteroid 25143 Itokawa by the Hayabusa spacecraft. Surface modification was found in 5 out of 10 particles, which varies depending on mineral species. Sulfur-bearing Fe-rich nanoparticles exist in a thin (5 to 15 nanometers) surface layer on olivine, low-Ca pyroxene, and plagioclase, which is suggestive of vapor deposition. Sulfur-free Fe-rich nanoparticles exist deeper inside (<60 nanometers) ferromagnesian silicates. Their texture suggests formation by metamictization and in situ reduction of Fe(2+).     

From a single-band metal to a high-temperature superconductor via two thermal phase transitions

The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature T* using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at T* of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (T(c)), entangled in an energy-momentum-dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.     

HPLC fluorometric determination of natural phytoplankton phycocyanin and its usefulness as cyanobacterial biomass in highly eutrophic shallow lake

A method for HPLC determination of phycocyanin in phytoplankton samples using gelchromatography with a fluorescence detector was developed to examine the use of phycocyanin as an index of the appearance and progress of cyanobacterial blooms in highly eutrophic lake. At least two types of phycocyanin with different molecular weights, each spectroscopically different from phycoerythrin and allophycocyanin, were found in natural phytoplankton samples. Changes in phycocyanin concentrations were clearly coupled to changes in chlorophyll-a concentrations during June to October while cyanobacterial blooms were occurring. The chlorophyll-a to phycocyanin relationship was linear at chlorophyll-a concentrations of less than 250 μg L^?1. The relationship between cyanobacterial carbon and phycocyanin concentration was also linear, suggesting that phycocyanin content may be a useful index of cyanobacterial biomass in highly eutrophic lakes where large cyanobacterial blooms occur.     

Inhibitory effects of oolong tea polyphenols on pancreatic lipase in vitro

Fifty-four polyphenols isolated from tea leaves were evaluated for their inhibitory activities against pancreatic lipase, the key enzyme of lipid absorption in the gut. (-)-Epigallocatechin 3-O-gallate (EGCG), which is one of major polyphenols in green tea, showed lipase inhibition with an IC50 of 0.349 microM. Moreover, flavan-3-ol digallate esters, such as (-)-epigallocatechin-3,5-digallate, showed higher activities of inhibition on lipase with an IC50 of 0.098 microM. On the other hand, nonesterified flavan-3-ols, such as (+)-catechin, (-)-epicatechin, (+)-gallocatechin, and (-)-epigallocatechin, showed zero and/or the lowest activities against pancreatic lipase (IC50 > 20 microM). These data suggested that the presence of galloyl moieties within the structure was required for enhancement of pancreatic lipase inhibition. It is well-known that flavan-3-ols are polymerized by polyphenol oxidase and/or heating in a manufacturing process of oolong tea. Oolonghomobisflavans A and B and oolongtheanin 3'-O-gallate, which are typical in oolong tea leaves, showed strong inhibitory activities with IC50 values of 0.048, 0.108, and 0.068 microM, respectively, even higher than that of EGCG. The oolong tea polymerized polyphenols (OTPP) were prepared for the assay from oolong tea extract, from which the preparation effectively subtracted the zero and/or less-active monomeric flavan-3-ols by preparative high-performance liquid chromatography. The weight-average molecular weight (Mw) and number-average molecular-weight (Mn) values of OTPP were 2017 and 903, respectively, by using gel permeation choromatography. OTPP showed a 5-fold stronger inhibition against pancreatic lipase (IC50 = 0.28 microg/mL) by comparison with that of the tannase-treated OTPP (IC50 = 1.38 microg/mL). These data suggested that the presence of galloyl moieties within their chemical structures and/or the polymerization of flavan-3-ols were required for enhancement of pancreatic lipase inhibition.     

Variations in plant and soil lead and mercury content in a major Honolulu Park, 1972 to 1987, a period of significant source reduction

The Ala Manna beach and park area in SE Honolulu is exposed to (1) local automotive exhaust emissions from the heavily travelled boulevard and high density shopping mall located immediately to the north; (2) a frequently congested access road located between the park proper and the beach; and (3) a remote source of geothermal and volcanic emissions 400 km to the SE on the Island of Hawaii. Between 1972 and 1987 both local Pb emissions and the more remote Hg emissions fell by more than 80%. Reductions in Pb reflected declining use of ‘leaded’ gasoline; reductions in Hg reflected a declining output of Hg⁰ vapor from volcanic and fumarolic sources. We compared Pb and Hg contents along a 150 m transect of soil and the grass Cynodon in 1972 and 1987. At the boulevard median divider, where particulate Pb deposition is heaviest, the metal content of the upper 5 to 6 cm of soil was reduced by approximately 53% but in the main body of the park no consistent pattern was found and an overall 21% reduction was observed. The highest soil Pb values were measured at the boulevard and beach access roads, with lower intermediate levels. The grass shoots showed a similar pattern but overall Pb content fell 65% between 1972 and 1979, a value more consistent with the reduction in Pb contamination from leaded gasoline. Neither soil nor plant Hg contents reflect a strong roadside to interior concentration gradient, but both fell between 1972 and 1987 by 60 and 68%, respectively. The biogeochemical significance of concentration ratios (plant/soil) and Pb/Hg atomic ratios was examined. With the exception of soil fixation of Pb in a relatively non-mobile soluble form, we conclude that for the two metals, the changes in levels reflect changes in the source (local for Pb and remote for Hg). There is also evidence for physiological regulation in the uptake of the two elements.     

Pathological studies on central nervous tissues of rats infected with Rattus serotype hantavirus (SR-11 strain).

Newborn rats inoculated intraperitoneally with a hantavirus strain (SR-11) developed neurological signs such as ataxia and limb paralysis. The main histological lesions were scattered and multiple neuronal degeneration and necrosis with eosinophilic cytoplasmic inclusion bodies (CIB) in the brain, spinal cord and ganglia. Immunohistochemically, the viral antigen was detected in neurons, capillary endothelial and glial cells throughout the nervous tissue and CIB were identified as consisting of hantaviral antigen (nucleocapsid protein). Ultrastructurally, CIB in the neurons consisted of an accumulation of granular or filamentous materials, or both. They were seen near a well-developed Golgi apparatus and associated with well-developed rough endoplasmic reticulum and increased numbers of ribosomes. The present results suggested that this virus strain was highly infective in neurons of the newborn rats and that excess production of viral antigen which accumulated as CIB resulted in the neuronal changes.     

An immunohistochemical study of the gastro-entero-pancreatic endocrine cells in the alimentary tract of the Korean tree squirrel, Sciurus vulgaris corea.

The regional distribution and relative frequencies of gastrointestinal endocrine cells were studied immunohistochemically in the gastrointestinal mucosa of Korean tree squirrels. Seven kinds of endocrine cells were identified in this study. Although a large number of 5-hydroxytryptamine-immunoreactive cells were seen throughout the gastrointestinal tract, they were most predominant in the duodenum. A moderate number of glucagon-immunoreactive cells which were restricted to the cardia and fundus of the stomach was also observed. Bovine chromogranin-immunoreactive cells were numerous in the cardia and pylorus of the stomach, found in moderate numbers in the fundus, duodenum and large intestine, but rare in the jejunum. Porcine chromogranin-immunoreactive cells were found in moderate numbers in the stomach but were rare in the duodenum. Gastrin/cholecystokinin-immunoreactive cells were abundant in the pyloric gland region but scarce in the duodenum. Bovine pancreatic polypeptide-immunoreactive cells were observed to be rare and found only in the pyloric gland region. Somatostatin-immunoreactive cells were distributed moderately in the stomach but were few in number in the intestine. No insulin-immunoreactive cells were found in the gastrointestinal tract of Korean tree squirrels. These results suggest that although the Korean tree squirrel is a herbivorous rodent, the distribution pattern of its gastro-entero-endocrine cells is rather similar to that reported for omnivorous animals.