The relationship between structure and function for the sulfite reductases

The six-electron reductions of sulfite to sulfide and nitrite to ammonia, fundamental to early and contemporary life, are catalyzed by diverse sulfite and nitrite reductases that share an unusual prosthetic assembly in their active centers, namely siroheme covalently linked to an Fe₄S₄ cluster. The recently determined crystallographic structure of the sulfite reductase hemoprotein from Escherichia coli complements extensive biochemical and spectroscopic studies in revealing structural features that are key for the catalytic mechanism and in suggesting a common symmetric structural unit for this diverse family of enzymes.     

Gathering and processing of lyme-grass (Elymus arenarius L.) in Iceland: an ethnohistorical account

Lyme-grass (Elymus arenarius L.) was harvested and processed for human consumption along the southern coast of Iceland until the beginning of this century. The origin of this exploitation is not known, but lyme-grass may have been gathered for this purpose already in the Viking Age. The system of processing lyme-grass is complex, and special implements and facilities are needed. The method is similar to traditional processing methods for cereals. Extensive research on Icelandic ethnographic observations was undertaken to establish the exact methods and sequence of operations that was involved. On the basis of this, a set of archaeological experiments was performed to test the viability of the processing techniques outlined in the written records. A model describing the harvesting and processing of lyme-grass is presented.     

鼠肝DNA甲基化酶的纯化及物理化学性质的研究

以Ｗｉｓｔａｒ大鼠肝为材料,确立了一个简便的纯化鼠肝ＤＮＡ甲基化酶的程序,包括：细胞的超声破碎、去内源核酸、硫酸铵盐析、磷酸纤维素亲和层析、ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ－５０柱层析及ＳｅｐｈａｄｅｘＧ－１５０凝胶过滤。用不同浓度聚丙烯酰胺凝胶电泳和孔梯度凝胶电泳检测,纯化后的酶已达电泳均一,且酶的比活力提高１１２倍。以聚丙烯酰胺孔梯度凝胶电泳测得其天然酶的分子量为３６５ｋＤ,以ＳＤＳ－聚丙烯酰胺凝胶电泳测得该酶有两种亚基,大亚基为９５ｋＤ,小亚基为８５ｋＤ,推测该酶由两个大亚基和两个小亚基组成。     

Changes in food intake,body weight,gonads and plasma concentrations of thyroxine,luteinizing hormone and testosterone in captive male buntings exposed to natural daylengths at 29° N

We have investigated the seasonal changes in food intake, body weight, gonadal volume and plasma concentrations of thyroxine, luteinizing hormone and testosterone in male blackheaded bunting (Emberiza melanocephala) in captivity under natural daylengths at 29° N. The cycles in food intake, body weight and testis size in buntings appeared to be phase related. While the changes in body weight and testicular size were parallel to each other and correspond to the increasing daylengths of spring and early summer, cycle in food intake was almost antiphase to the cycles in body weight and testicular growth and development. Furthermore, buntings showed a distinct seasonal cycle in plasma concentrations of thyroxine, luteinizing hormone and testosterone. It is suggested that these seasonal cycles in buntings are endogenously programmed and their entrainment to the environmental photoperiod ensures the occurrence of different physiological functions at temporally fixed time of the year.     

Nitric oxide is involved in heat-induced HSP70 accumulation

Heat shock potentiated the nitric oxide production (EPR assay) in the liver, kidney, heart, spleen, intestine, and brain. The heat shock-induced sharp transient increase in the rate of nitric oxide production preceded the accumulation of heat shock proteins (HSP70) (Western blot analysis) as measured in the heart and liver. In all organs the nitric oxide formation was completely blocked by the NO-synthase inhibitor (L-NNA). L-NNA also markedly attenuated the heat shock-induced accumulation of HSP70. The results suggests that nitric oxide is involved in the heat shock-induced activation of HSP70 synthesis.     

Correspondence of environmental tolerances with leaf and branch attributes for six co-occurring species of broadleaf evergreen trees in northern California

 For the angiosperm dominants of northern California’s mixed evergreen forests, this study compares the display of photosynthetic tissue within leaves and along branches, and examines the correspondence between these morphological attributes and the known environmental tolerances of these species. Measurements were made on both sun and shade saplings of six species: Arbutus m e n z i e s i i (Ericaceae), C h r y s o l e p i s c h r y s o p h y l l a (Fagaceae), L i t h o c a r p u s d e n s i f l o r u s (Fagaceae), Quercus c h r y s o l e p i s (Fagaceae), Quercus w i s l i z e n i i (Fagaceae), and Umbellularia c a l i f o r n i c a (Lauraceae). All species had sclerophyllous leaves with thick epidermal walls, but species differed in leaf specific weight, thickness of mesophyll tissues and in the presence of a hypodermis, crystals, secretory idioblasts, epicuticular deposits, and trichomes. The leaves of Arbutus were 2 – 5 times larger than those of C h r y s o l e p i s, L i t h o c a r p u s and Umbellularia and 4 – 10 times larger than those of both Quercus species. Together with differences in branch architecture, these leaf traits divide the species into groups corresponding to environmental tolerances. Shade-tolerant C h r y s o l e p i s, L i t h o c a r p u s, and Umbellularia had longer leaf lifespans and less palisade tissue, leaf area, and crown mass per volume than the intermediate to intolerant Arbutus and Quercus. Having smaller leaves, Quercus branches had more branch mass per leaf area and per palisade volume than other species, whereas Arbutus had less than other species. These differences in display of photosynthetic tissue should contribute to greater growth for Quercus relative to the other species under high light and limited water, for Arbutus under high light and water availability, and for C h r y s o l e p i s, L i t h o c a r p u s, and Umbellularia under limiting light levels. Accepted: 22 March 1996     

Construct Validity of the Impact of Weight on Quality of Life Questionnaire

KOLOTKIN, RONETTE L, SUSAN HEAD, ALAN BROOKHART. Construct validity of the Impact of Weight on Quality of Life questionnaire. The Impact of Weight on Quality of Life questionnaire (IWQOL) is a 74-item self-report, condition-specific instrument that (1) assesses the effect of weight on quality of life in eight key areas, and (2) may be used as a treatment outcome measure and/or an evaluation tool for healthcare policy makers and third-party payers. This study explores IWQOL construct validity and provides new information on internal consistency, treatment effects, and differences between men and women. IWQOL total scores correlated highly with other measures of overall quality of life, and subscale scores correlated well with counterparts in the assessment battery. Internal consistency estimates for the IWQOL scales generally were high. For the women, 4-week participants, and the total sample, pretreatment-posttreatment differences were significant for all IWQOL scales and total score. For men, treatment differences were significant for the total score and all subscales except for Work and Mobility. Treatment differences for 2-week participants were significant for all scales except for Work. Consistent with previous IWQOL study results, the Comfort With Food scale scores reflected more discomfort at posttreatment as compared with pretreatment. The IWQOL, already translated into French and Italian, currently is demonstrating clinical and research utility as a quality-of-life outcome measure for clinical trials of antiobesity drugs and surgical treatments for patients with obesity.     

Plant diversity in late medieval cornfields of northern Switzerland

Weed assemblages from late medieval cornfields have been studied for the first time in northern Switzerland. Eleven samples from at least two different grain stores were investigated. The samples were collected from the carbonised remains of six wooden houses built in the late 13th century A.D. and which burnt down in the middle of the 15th century. The weed floras found in the spelt (Triticum spelta) and oats (Avena sativa) indicate a high botanical diversity in the cornfields at harvest time. Although oats are normally a summer crop and spelt a winter crop, both summer and winter crop weeds (as well as many different present-day grassland taxa) were found in each type of grain. Most of the weeds found were perennial plants, which was interpreted as an indication of both extensive tillage of the arable land and application of the three-field rotation system (Dreifelderwirtschaft). The spectra of the two palaeophytocoenoses (assemblages of ancient plant remains) studied suggest that the phytosociological method may not be reliable for classification of the late medieval remains into summer and winter crop weed communities. These findings should provide a better understanding of the development of anthropogenic plant communities, and in particular, the development of crop weed communities.