Factors determining the pest status of the rose-grain aphid, Metopolophium dirhodum (Walker), on winter barley in the United Kingdom

To test the hypothesis that early maturation of barley affords it some resistance to cereal aphids, the colonisation, survival, growth, reproduction and emigration of M. dirhodum on barley was measured and compared with previously published results for this aphid on wheat.
Barley plants were colonised as readily as wheat plants. Survival to maturity was similar on both hosts. Relative growth rate was higher on wheat than on barley for most of the season while reproduction was similar on both. Emigration, measured alate production, was significantly higher on mature wheat than on mature barley.
It is proposed that the increase of M. dirhodum populations on barley is normally terminated early in the year directly plant maturation and consequent drying out of the leaves, resulting in the death of aphids. This is different to the situation on wheat, which matures later, and where emigration following plant induced alate induction has been shown to be the major factor affecting the decline in population growth.
These results support the hypothesis that early maturation of barley provides some resistance to M. dirhodum.     

Interactions between diurnal temperature fluctuations and salinity on expansion growth and water status of young tomato plants

Expansion growth is limited if the difference between day and night temperature (DIF) is negative. Growth is also limited high salinity. Expansion growth of tomato seedlings was studied under day/night temperatures of 16/24°C and 24/16°C, and nutrient solution salinities of 3 and 15 mS cm^-1 to ascertain whether interactions exist between the two stress forms. Water status was also studied in order to assess possible mechanisms of growth retardation. A significant interaction between DIF and salinity was found for all recorded growth variables. Hypocotyl length, plant height, leaf area and fresh and dry weight were lower at negative DIF than at positive, the reduction being greater at low salinity than at high. Increased salinity also reduced growth, more so at positive DIF than at negative. Growth reduction at negative DIF was accompanied increased shoot water and osmotic potentials. Pressure potential was unaffected DIF. Growth reduction at high salinity was accompanied reduced water and osmotic potentials. Pre-dawn pressure potential was increased at high salinity, whereas no effect of salinity on pressure potential at midday was found. The differences in effects on water status between the two stress forms may suggest differing mechanisms of growth retardation.     

Depleted mucosal antioxidant defences in inflammatory bowel disease

Experimental approaches designed to define the role of reactive oxygen and nitrogen species generated by inflammatory cells in the tissue injury seen in inflammatory bowel disease rarely consider the chemical antioxidant defences against such increased oxidant stress in the mucosa. In this investigation, we have analysed components of the aqueous and lipid phase antioxidant mucosal defences by measuring the total peroxyl radical scavenging capacity and the levels of urate, glutathione, -tocopherol, and ubiquinol-10 in paired noninflamed and inflamed mucosal biopsies from inflammatory bowel disease patients. Compared to paired noninflamed mucosa, decreases were observed in inflamed mucosa for total peroxyl radical scavenging capacity (55%, p = 0.0031), urate [Crohn's disease (CD), 62.2%, p = 0.066; ulcerative colitis (UC), 47.3%, p = 0.031], glutathione (UC, 59%, 7/8 patients, ns), total glutathione (UC 65.2%, 6/8 patients, ns), ubiquinol-10 (CD, 75.7%, p = 0.03; UC, 90.5%, p = 0.005). The mean -tocopherol content was unchanged. These observations support our earlier findings of decreased reduced and total ascorbic acid in inflamed IBD mucosa and demonstrate that the loss of chemical antioxidant defences affects almost all the major components. The decreased antioxidant defences may severely compromise the inflamed mucosa, rendering it more susceptible to oxidative tissue damage, hindering recovery of the mucosa and return of epithelial cell layer integrity. The loss of chemical antioxidant components provides a strong rationale for developing novel antioxidant therapies for the treatment of inflammatory bowel disease.     

Growth patterns of early versus late successional multipurpose trees of the western Himalaya

In the mid-western Himalaya (altitude 1350 m, rainfall 1100 mm), multipurpose trees found as escapees in agricultural fields or naturally growing in the forests, play an important role in providing fuel, fooder and small timber to the farmers. Shoot elogation, and tree architecture of 4 year old trees of Grewia optiva, Robinia pseudoacacia and Celtis australis (early successionals), and Quercus leucotrichophora, Q. glauca and Ilex odorata (late successionals), were analyzed. All the late successional species showed a proleptic type of bud and branch production, while the early successional trees made growth through syllepsis. The shoot elongation differed significantly (P <0.05) with the crown position, and ranged from 11 to 30 cm in different species. Early successional species tended to maintain a comparatively narrow crown and showed a significantly (P <0.05) higher ramification ratio, and multilayered canopy. The late successionals, in contrast, showed a wide crown with monolayered canopy, adapted to the weak light intensity. There was only one flush of leaves in Q. leucotrichophora and Q. glauca while in the rest of the species there were two distinct flush periods. The results are important for the management of agroforestry trees.     

蒲洼农业生态系统能流的稳定性及其动态

在研究生态系统结构及功能的基础上,本文基于１９７５－１９９０年的数据,对蒲洼农业生态系统能流的稳定性及其动态进行了分析。通过建立能流模型,由李雅普诺夫稳定性原理,得出该生态系统能流的平衡态具有渐近稳定性。动态数学模拟表明,目前该系统的能量流动正从不稳定状态向稳定和平衡态过渡,这一过程大约需要７ａ时间。     

The effect of glyceraldehyde on red cells: Haemoglobin status,oxidative metabolism and glycolysis

Glyceraldehyde induces changes in the flux of glucose oxidised through the hexose monophosphate pathway, the concentrations of intermediates in the Embden-Meyerhoff pathway, the oxidative status of haemoglobin and levels of reduced and oxidised pyridine nucleotides and glutathione in red cells. Glyceraldehyde autoxidises in the cellular incubations, consuming oxygen and producing glyoxalase I- and II-reactive materials. Major fates of glyceraldehyde in red cells appear to be: (i) adduct formation with reduced glutathione and cellular protein; (ii) autoxidation and reaction with oxyhaemoglobin and pyridine nucleotides, and (iii) phosphorylation of d-glyceraldehyde and entry into the glycolytic pathway as glyceraldehyde 3-phosphate. The production of glycerol from glyceraldehyde by red cell l-hexonate dehydrogenase appears not to be a major reaction of glyceraldehyde in red cells. These results indicate that high concentrations of glyceraldehyde (1–50 mM) may induce oxidative stress in red cells by virtue of the spontaneous autoxidation of glyceraldehyde, forming hydrogen peroxide and α-ketoaldehydes (glyoxalase substrates). The implications of glyceraldehyde-induced oxidative stress for the in vitro anti-sickling effect of dl-glyceraldehyde and for the polyol pathway metabolism of glyceraldehyde are discussed.     

Intragroup agonistic behavior in captive groups of the common marmosetCallithrix jacchus jacchus

Agonistic behavior was observed in five captive groups of the monogamous monkey Callithrix jacchus jacchus,which normally produces twin offspring every 5 months. Fighting is first recorded when twins are aged 5–10 months. These “twin fights” determine differences in status between combatants that can be detected 5 months later. From what is known of the social behavior of the species, it is postulated that an individual’s twin is its most serious rival and that early fighting is advantageous because injury is minimal while the animal retains its milk dentition. In contrast to twin fights, aggression between same-sex juveniles and adults does not involve long fights and probably serves to reinforce preexisting differences in status. It often results in forcing a group member to the periphery, and therefore, its main function may be to drive mature, same-sexed individuals out of the group. Apart from the relationship between twins, status within the family group is age related and not normally determined by aggression.     

Catalase activity and isozyme pattern of the metalloenzyme system, superoxide dismutase, as a function of leaf development during growth of Pisum sativum L. plants

The catalase activity and the isozyme pattern of the metalloenzyme system superoxide dismutase (SOD) have been determined in pea ( Pisum sativum L., cv, Lincoln) leaves of different ages (apical, middle and lower), during several stages of plant development. Pea seedlings were grown in full nutrient solution in a phytotron. Catalase activity was determined polarographically, and superoxide dismutase isozymes (Mn-SOD, Cu, Zn-SOD I and Cu, Zn-SOD II) were separated by acrylamide gel electrophoresis and their relative amounts quantified by densitonietry. The results indicate that the relative amounts of SOD isozymes are slightly different in leaves of different ages during plant growth and, interestingly, each molecular form of SOD shows a clearly distinct pattern during plant development. These changes in the relative percentages of SOD isozymes could be due to the induction of the distinct molecular forms of SOD by the metals Mn, Cu and Zn, translocated to the different leaves as a result of plant development. The relative percentage of the Mn-SOD isozyme showed a similar pattern to that of catalase activity, suggesting a possible link between these two metalloenzymes at subcellular level, both cooperating to remove the toxic effects of O^-₂ and H₂O₂.
An additional conclusion is that before a certain metalloenzyme can be used as a marker to assess the plant micronutrient status, it is essential to have a detalled study of its activity pattern in leaves of different age during plant development.     

Effects of excess selenomethionine on selenium status indicators in pregnant long-tailed macaques (Macaca fascicularis)

Forty pregnant long-tailed macaques were treated daily for 30 d with 0, 25, 150 or 300 μg selenium as L-selenomethionine/kg body weight. Erythrocyte and plasma selenium and glutathione peroxidase specific activities, hair and fecal selenium, and urinary selenium excretion were increased by and were linearly related to L-selenomethionine dose. Hair selenium was most sensitive to L-selenomethionine dose, with an 84-fold increase in the 300 μg selenium/(kg-d) group relative to controls (r=0.917). Daily urinary selenium excretion (80-fold,r=0.958), plasma selenium (22-fold,r=0.885), erythrocyte selenium (24-fold,r=0.920), and fecal selenium (18-fold,r=0.911) also responded strongly to L-selenomethionine. Erythrocyte and plasma glutathione peroxidase specific activities increased 154% and 69% over controls, respectively. Toxicity was associated with erythrocyte selenium >2.3 μg/mL, plasma selenium >2.8 μg/mL, and hair selenium >27 μg/g. Plasma, erythrocyte, and hair selenium concentrations may be useful for monitoring and preventing the toxicity of L-selenomethionine administered to humans in cancer chemoprevention trials.     

Interleukin 2 production in iron-deficient children

The relationship between iron status and capacity for IL-2 production by lymphocytes was assessed in 81 children from 6 mo to 3 yr of age selected at random from a population with low socioeconomic status, undergoing free systematic examination in four children's health centers in the Paris area. Iron deficiency was defined by the existence of at least two abnormal values among the three indicators of iron status: serum ferritin level ≤12 μg/L, transferrin saturation <12%, and erythrocyte protoporphyrin concentration >3 μg/g hemoglobin. According to this definition, 53 children were classified as iron deficient and 28 as iron sufficient. No differences were observed between the iron-deficient and iron-sufficient groups in terms of the IL-2 concentration without stimulation by PHA. IL-2 production by lymphocytes stimulated with PHA, as well as the stimulation index (ratio of IL-2 concentration following stimulation by PHA to that of IL-2 concentration without stimulation by PHA) were significantly lower in iron-deficient children. The reduction in IL-2 production by activated lymphocytes observed in our study of iron-deficient children may be responsible for impairments in immunity found by other authors, particularly in cell-mediated immunity.