Age at menopause of Tamang women tea-labourers of Jalpaiguri district,West Bengal,India

The Tamang women tea-labouren of Jalpaiguri district show no significant difference in age at menopause among their three «migration status» groups, viz., MO, M1 and M2+. The mean age at menopause is 47.3±4.26 and the median age is 47.68 years. A significant difference occurs between the observed mean age at menopause and 45 years, which is generally taken to be the menopausal age by convention. These Tamang women seem to be similar to other hill women in respect of age at menopause.     

绿茶抗氧化剂成分抑制突变作用的初步研究

绿茶水溶性提取物及茶叶中抗氧化剂成份具有明显的抑制AFB_1及Bap诱导的鼠伤寒沙门氏菌回复突变作用。这种抗氧化剂成份还可以抑制AFB_1和Bap诱导的V79细胞基因正向突变,以及AFB_1诱导的V79细胞SCE和染色体畸变。本实验结果提示,绿茶中抗氧化剂成份可能对AFB_1及Bap的致癌性具有抑制作用。本文就茶叶抗氧化剂抑制突变的可能机制进行了初步讨论。     

中国某些野生和栽培茶的核型研究

研究了茶的4个变种和广东野生毛叶茶等共12个材料的核型。所有材料的染色体数目均是2n=30,为二倍体。所有中国大叶变种(越南大叶除外)(Cametlia sinensis var. macrophylla)和阿萨姆大叶变种(C. sinensis var. assamica)均具比较对称或原始的“2A”核型;中国小叶变种(C.sinensis var.bohea)(“铁观音”品种除外),掸部变种(C.sinensis var. shan form)和广东野生毛叶茶(C. ptilophylla)均具较不对称或较进化的“2B”核型。根据核型特征,植物习性和地理分布,作者认为中国四川和云南可能是茶的起源中心,向东或北迁移,演变为中国小叶变种;向南移则演变为阿萨姆变种和掸部变种。     

Decomposition of Eucalyptus globulus leaves and three native leaf species (Alnus glutinosa, Castanea sativa and Quercus faginea) in a Portuguese low order stream

Leaf decomposition of the exotic evergreen Eucalyptus globulus (eucalyptus), and three native deciduous tree species, Alnus glutinosa (alder), Castanea sativa (chestnut) and Quercus faginea (oak), was compared in a second order stream in Central Portugal. Changes in dry weight, nitrogen and polyphenolic compounds and microbial colonization were periodically assessed for three months.Negative exponential curves fit the leaf weight loss with time for all leaf species. Mass loss rate was in the order alder (K = 0.0161) > chestnut (K = 0.0079) > eucalyptus (K = 0.0068) > oak (K = 0.0037). Microbial colonization followed the same pattern as breakdown rates. Evidence of fungal colonization was observed in alder after 3 days in the stream, whereas it took 21 days in oak leaves to have fungal colonization. Fungal diversity was leaf species-dependent and increased with time. In all cases, percent nitrogen per unit leaf weight increased, at least, at the initial stages of decay while soluble polyphenolics (expressed as percentage per unit leaf weight) decreased rapidly in the first month of leaves immersion.Intrinsic factors such as nitrogen and polyphenolic content may explain differences in leaf decomposition. The possible incorporation of eucalyptus litter into secondary production in a reasonable time span is suggested, although community balance and structure might be affected by differences in allochthonous patterns determined by eucalyptus monocultures.     

Somatic embryogenesis from immature leaves of in vitro grown tea shoots

Immature leaves of in vitro grown shoots of tea were cultured on various levels of 2,4-D. Somatic embryos were induced directly on leaves or via embryogenic callus produced at the basal regions of the leaves. Induction of embryogenesis appeared to be correlated with the maturity of the leaf explants, with younger leaves responding better. The embryogenic response of leaf explants also was correlated with the period of culture in 2,4-D containing liquid medium. Embryogenic calli or repetitive somatic embryos maintained their regeneration capacity for more than 3 years. Histological observation revealed somatic embryos were formed on various regions of the leaf midrib. Somatic embryos germinated and developed into plantlets on agar medium containing BA and IBA.Abbreviations BA 6-benzylaminopurine - IBA indole-3-butyricacid - 2,4-D 2,4-dichloro phenoxyacetic acid     

Black tea,green tea,and tea polyphenols

Previous studies have shown that tea consumption can impair trace element metabolism, particularly iron status, and increase the risk of anemia in humans and animals. More recently, however, evidence has been accumulating to show that, in animals, consumption of green tea or its polyphenols is associated with a reduction of the incidence and severity of a variety of experimentally induced cancers. In this study we have monitored the growth, trace element status, including hematological parameters of weanling rats given either (1) water, (2) 1% black tea, (3) 1% green, tea, or (4) 0.2% crude green tea extract as their sole drinking fluid while consuming diets containing either adequate or low amounts of iron. With the exception of manaanese, none of the trace elements studied (iron, copper, zinc, and manganese) or the hematological indices measured were affected by the type of beverage supplied, even though the polyphenol extract was shown to chelate metals in vitro and all the animals fed the low iron diet were shown to be anemic. There appeared to be an effect of black and green teas on manganese balance in, both the first and last weeks of the study. A lower level of brain managanese was associated with green tea consumption, and a higher level of this element in the kidneys of animals fed black tea. The results demonstrate that both black and green teas and a green tea polyphenol extract do not represent a risk to animals consuming the beverages as their sole fluid intake with respect to iron availability, although the interactions with manganese deserve further study.     

Impact of residue quality on the C and N mineralization of leaf and root residues of three agroforestry species

A laboratory incubation experiment with ¹⁵N labeled root and leaf residues of 3 agroforestry species (Leucaena leucocephala, Dactyladenia barteri and Flemingia macrophylla) was conducted under controlled conditions (25 C) for 56 days to quantify residue C and N mineralization and its relationship with residue quality.No uniform relation was found between the chemical composition of the above and below residues. The leucaena and dactyladenia roots contained more lignin (8 and 26% respectively) and less N (2.0 and 1.0% respectively) than the respective leaves (2 and 13% lignin and 2.9 and 1.4% N, respectively), whereas the differences between the lignin and N contents of the flemingia leaves and roots were not significant (4.6 and 3.0% lignin and 2.63 and 2.68% N, respectively). The leucaena leaves contained more polyphenols than the roots (6.4 and 3.6%), while the polyphenol content of the leaves and roots of the other residues was similar (5.0 and 5.1% for dactyladenia and 4.0 and 3.5% for flemingia).Three patterns of N mineralization could be distinguished. A first pattern, followed by residues producing the highest amounts of CO₂, showed an initial immobilization of soil derived N, followed by a net release of both soil and residue derived N after 7 days of incubation. A second pattern, followed by the flemingia leaf residues which produced intermediate amounts of CO₂ and had an intermediate quality, showed no significant immobilization of soil derived N, and significant mineralization of residue N. A third pattern, followed by both low quality dactyladenia residues, showed a low release of residue derived N and a continued inmobilization of soil derived N.Residue C mineralization was significantly (p<0.05) correlated with the residue lignin content, C-to-N ratio, and polyphenol-to-N ratio. The proportion of residue N mineralized (immobilized) after 56 days of incubation was significantly correlated with the residue N content (p<0.01) and the C-to-N ratio (p<0.05). The relations were quadratic, rather than linear. The ratio of the proportion of residue N mineralized (immobilized) over the proportion of residue C mineralized after 56 days was highly significantly correlated with the lignin content (p<0.01) and C-to-N (p<0.001), lignin-to-N (p<0.01), polyphenol-to-N (p<0.01) and (lignin+polyphenol)-to-N ratios (p<0.01) in a linear way. This indicates that due to the low availability of the residue C, relatively less N is immobilized for the very low quality residues ((lignin+polyphenol)-to-N ratio: 29.7) than for the residues with a relatively higher quality ((lignin+polyphenol)-to-N ratios between 3.3 and 12.5).     

Influence of soil applied nitrogen (NPKS 25: 5: 5:5) on Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae) mite incidence and damage symptoms on tea

Application of nitrogenous fertilisers (NPKS 25: 5: 5:5) for yield of tea and to induce tolerance to the red crevice ( Brevipalpus phoenicis Geijskes) mite was found to be rates between 150 and 200 Kg N ha^-1 yr^-1 rates above 400 Kg N ha^-1 encouraged the build up of mites on tea. Damage symptoms resulting from mite infestation declined with increase in application of nitrogenous fertilisers.
The levels of nitrogen in the leaf tissues increased with soil applied nitrogen and also was related to the mite numbers found on the leaves suggesting a link. The symptoms of the discoloured necrotic leaf base that accompanied mite infestation was significantly ( P ≤ 0.05) and linearly correlated (r = 0.60) to mite numbers in the control plot. The levels of applied nitrogen were negatively correlated to % leaf necrosis suggesting a tolerance leading to reduction in necrotic symptoms with fertiliser applications.     

Structure-antioxidant activity relationships of flavonoids and phenolic acids

The recent explosion of interest in the bioactivity of the the flavonoids of higher plants is due, at least in part, to the potential health benefits of these polyphenolic components of major dietary constituents. This review article discusses the biological properties of the flavonoids and focuses on the relationship between their antioxidant activity, as hydrogen donating free radical scavengers, and their chemical structures. This culminates in a proposed hierarchy of antioxidant activity in the aqueous phase. The cumulative findings concerning structure-antioxidant activity relationships in the lipophilic phase derive from studies on fatty acids, liposomes, and low-density lipoproteins; the factors underlying the influence of the different classes of polyphenols in enhancing their resistance to oxidation are discussed and support the contention that the partition coefficients of the flavonoids as well as their rates of reaction with the relevant radicals define the antioxidant activities in the lipophilic phase.     

激光照射茶树花药培养及其过氧化物酶同工酶的分析

Ｈｅ－Ｎｅ和ＣＯ２激光对茶树花药培养的药裂率和出愈率的影响,既有促进作用,也有抑制作用。按出愈率和愈伤组织生长状况的序列：Ｈｅ－Ｎｅ：２０Ｊ／ｃｍ＾２〉ＣＫ〉Ｈｅ－Ｎｅ：３０Ｊ／ｃｍ＾２〉ＣＯ２：３５．４Ｊ／ｃｍ＾２。对Ｈｅ－Ｎｅ激光照射花药及其愈伤组织的过氧化物酶同工酶分析,主要表现在弱酶带的变化上,无规律差异。