Effects of winter flooding on phosphorus dynamics in rice fields

Limnology - Controlling phosphorous (P) loads from rice fields is important for the conservation of aquatic ecosystems, in part because P is relatively concentrated at its sources. Recently, winter...     

How to discriminate between vibration syndrome and local fatigue of motorcyclists

Motorcyclists who work in some offices sometimes complained of coldness, pain and numbness of upper limbs. We studied how to discriminate between vibration syndrome and local fatigue of the motorcyclists. Subjects are 42 motorcyclists of an office in Aichi prefecture. 25 of them held several letters in their left hand when they delivered the letters. They complained of coldness, pain and numbness in the left upper limbs more than in the right limbs (p less than 0.01). We think that it is the local fatigue rather than the disorder of vibration syndrome that causes such symptoms. So it is very important to recognize the existence of local fatigue in order to know how to discriminate between vibration syndrome and local fatigue of the motorcyclists.     

Age-related differences in muscle activity, stride frequency and heart rate response during walking in water.

This study aimed to examine whether walking in water produces age-related differences in muscle activity, stride frequency (SF), and heart rate (HR) response. Surface electromyography (EMG) was used to evaluate muscle activities in six older and six young subjects while they walked in water immersed to the level of the xiphoid process. The trials in water utilized the Flowmill which consists of a treadmill at the base of a water flume. The measurement of maximal voluntary contraction (MVC) of each muscle was made prior to the gait analysis. The %MVCs, which refer to the surface EMG measures, from the gastrocnemius of the older subjects were significantly lower than those of the young subjects, in every experimental condition (P<0.05). In contrast, the %MVCs from the rectus femoris (P<0.05) and the biceps femoris (P<0.001) of older subjects were significantly greater than those of young subjects in every experimental condition. Moreover, the SFs of older subjects were also significantly greater than those of young subjects (P<0.05), while the HR responses of older and young subjects were similar. In conclusion, the older subjects had increased hip musculature activity and decreased ankle plantar flexor activity while walking in water, compared with the young subjects.     

Structure and expression of cDNA for an inhibitor of blood coagulation isolated from human placenta: a new lipocortin-like protein

An inhibitor of blood coagulation, a new protein with an apparent molecular weight of 34,000 and an isoelectric point of 4.9, was purified from human placental tissue by EDTA extraction. Five cDNA clones were isolated from the human placental lambda gt11 cDNA library using the mouse monoclonal antibody raised against the coagulation inhibitor as the probe. The longest insert consists of 1,566 nucleotides, and contains 960 nucleotides entirely encoding the 320 amino acids of the inhibitor, and a poly A tail. The deduced amino acid sequence was corroborated by chemical analyses of the protein. The entire amino acid sequence shows homology to those of lipocortin I, lipocortin II, and endonexin-related proteins. The cDNA for the inhibitor was expressed in Escherichia coli under the regulation of the trc promotor of the plasmid pKK233-2. The resulting recombinant protein manifested inhibitory activities against both blood coagulation and phospholipase A2 activity, as did the coagulation inhibitor isolated from human placenta.     

Glutamine Synthetase of the Human Brain: Purification and Characterization

Glutamine synthetase (GS) isolated from human brain formed a single band on sodium dodecyl sulfate-polyacrylamide gel with a molecular weight of 44,000. The enzyme had a specific activity of 179.2 U/mg protein when assayed by measuring the rate of the formation of gamma-glutamylhydroxamate using hydroxylamine as a substrate. In the presence of manganese ions, the relative activity of human brain GS was much lower than that of the sheep brain enzyme. The suppression of activity by increasing the ADP concentration, however, was less marked in the human enzyme than that in the sheep enzyme. Antibodies were raised in rabbits against the purified enzyme. The double-immunodiffusion technique disclosed cross-reactivities among GSs isolated from human, sheep, and rat brains, but the enzymes were not immunologically identical. Immunohistochemically, GS was localized in the cytoplasm of astrocytes in the human and rat brains and in pericentral hepatocytes of the liver.     

Involvement in DNA repair of the ruvA gene of Escherichia coli

Summary The ruv operon of Escherichia coli consists of two genes, orfl1 and ruv, which encode 22 and 37 kilodalton proteins, respectively, and are regulated by the SOS system. Although the distal gene, ruv, is known to be involved in DNA repair, the function of orf1 has not been studied. To examine whether orf1 is also involved in DNA repair, we constructed a strain with a deletion of the entire ruv operon. The strain was sensitive to UV even after introduction of low copy number plasmids carrying either orf1 or ruv, but UV resistance was restored by introduction of a plasmid carrying both orfl and ruv. These results suggest that orf1 as well as ruv is involved in DNA repair. Therefore, orf1 and ruv should be renamed ruvA and ruvB, respectively.     

Mutagenicity of ptaquiloside, the carcinogen in bracken, and its related illudane-type sesquiterpenes II. Chromosomal aberration tests with cultured mammalian cells

The chromosomal aberration test using a Chinese hamster lung cell line (CHL) was carried out on ptaquiloside and its related compounds, hypoloside B, hypoloside C, illudin M and illudin S. Ptaquiloside induced chromosomal aberrations at doses as low as 4.5 μg/ml (0.0113 mM). The clastogenic effect was ph-dependent. The same activity was observed at a 90-fold higher dose at pH 5.3 in the culture medium compared with the activity at pH 74. or pH 8.0. Both hypoloside B and hypoloside C were also clastogenic at almost the same dose levels as that of ptaquiloside. Illudin M and illudin S were also potet clastogens and induced aberrations at much lower doses than ptaquiloside. These results suggest that the clastogenic effect is involved in the mechanism of carcinogenic potency of ptaquiloside in animals.     

Electron Transfer between Plastocyanin and P700 in Various Types of Photosystem I Complex

Three types of PS I Chl-protein complex, PS I 180, PS I 65,and PS I 30, have been prepared and the kinetic properties ofthe transfer of electrons from plastocyanin to P700 in the PSI complexes with different sized antennae were examined. ThePS I 180 complex, which consists of 180 Chi per P700, showedthe almost same rate constant and effects of cations for thetransfer of electrons from plastocyanin to P700 as those obtainedwith PS I-enriched membrane fragments. The rate constant increasedwith the addition of low concentrations of monovalent and divalentcations, but decreased with high concentrations of cations.However, the rate was severely reduced in the case of the PSI 65 and PS I 30 complexes, and quite different effects of cationswere observed. Given the presence of additional 25- to 28-kDapolypeptides in the PS I 180 complex as compared to the PS I65 and PS I 30 complexes, we discuss a possible function forthese polypeptides in the regulation of the reaction betweenplastocyanin and P700. ¹This work was supported in part by a Grant-in-Aid for ScientificResearch from the Ministry of Education, Science and Cultureof Japan. (Received May 27, 1988; Accepted November 7, 1988)     

Immunohistochemical localization of proteoglycans in interstitial elements of human pancreas and biliary system

Summary The immunohistochemical localization of large proteoglycan and small proteoglycan was observed, using antibodies 2B1 and 6B6 (Sobueet al., 1988, 1989a), in fetal and adult pancreas and biliary system as well as in tumour tissues, obtained from 11 autopsies and 74 biopsies. The distribution of chondroitin 4- and 6-sulphate side chains, type I and IV collagen and elastin were also studied. In adult pancreas and all the biliary tracts examined, periductal fibrous tissues consisted mainly of dermatan sulphate small proteoglycan with networks of fibrous elements, which were composed of large proteoglycan, elastin, type I collagen and type IV collagen. In the interstitial components of cystadenoma of pancreas and biliary duct carcinoma, similar small proteoglycan-rich components were relatively abundant, although large proteoglycan was present in much larger amounts than that in non-neoplastic adult tissues. In some cholangiomas, the extra-and intracellular hyaline globules formed by the carcinoma cells were found to contain chondroitin sulphate large proteoglycan, laminin and fibronectin.The distribution of proteoglycans was observed to be different in the arterial walls of the interlobular tissues of the adult and the fetal pancreas. The biological significance of large and small proteoglycans in the interstitial connective tissues was discussed.