The Evolution of Avian Senescence Patterns: Implications for Understanding Primary Aging Processes

SYNOPSIS. The long life spans of birds relative to those ofmammals are intriguing to biogerontologists, particularly inlight of birds' high body temperatures, high blood glucose levels,and high metabolic rates—all of which should theoreticallyincrease their biochemical liability for rapid aging. The comparativelongevity of birds and other flying homeotherms is consistentwith evolutionary senescence theory, which posits that specieswith low mortality rates from predation or accident will bereleased from selection for rapid maturity and early reproduction,and will exhibit retarded aging. Comparative analyses of avianlife history parameters to date, although not as extensive asthose for mammals, broadly support an association between lowmortality rates, slow reproduction, and long lifespan. The diversityof bird life histories suggests the importance of developinga diversity of avian models for studies of aging mechanisms,both proximate and ultimate, and for using wild as well as domesticrepresentatives. Birds studied in the laboratory thus far showmany of the same manifestations of aging as mammals, includinghumans, and many ornithologists are beginning to document actuarialevidence consistent with aging in their study populations. Weencourage greater communication and collaboration among comparativegerontologists and ornithologists, in the hope that the studyof aging in birds will lead to an integrated understanding ofphysiological aging processes well grounded in an evolutionaryparadigm.     

Understanding global change: Lessons learnt from the European landscape

Abstract. Europe is characterized not only by large geomorphological variability but also by a long history of land use. This resulted in a highly variegated landscape. Based on the IGBP‐transect initiative, a north south transect was established across Europe ranging from north Sweden to central Italy in order to study effects of global change. Mainly process oriented studies were established on plots along the transect, and these were used to establish functional relationships as basis for landscape integration. However, it became apparent that the transect approach was not sufficient to mirror the European environment. From early on, the assessment of land cover was not constrained to this transect but complemented with measurements focused on Europe at a continental scale. Also, continental networks of flux measurements and ecosystem experiments were established, because these were able to encompass a larger inherent variability of climate, geology and land use. Resulting from the Kyoto protocol emphasis moved stronger from observations along transects towards a continental scale quantification of fluxes given the reporting needs. In this process the transect and the networks merged into research clusters, which provided a scaling and verification mechanism. Thus, the European situation may serve as an example of how the initial idea of transects has further evolved and broadened to continental scale studies in a region where anthropogenic land use dominates over climate change.     

Maintaining the Coffee Canopy: Understanding Change and Continuity in Central Veracruz

This paper examines land-use changes and continuities following historic price declines and withdrawal of government support for coffee cultivation in Veracruz, Mexico. A time series analysis of satellite imagery from the municipalities of Xico and Coatepec was carried out to assess changes in one of Latin America’s oldest coffee-producing regions. Two case study communities were selected for in-depth assessment, including semi-structured interviews, household surveys and participant observation. This study demonstrates while small parcels were converted to new land-uses, 82 % of coffee/forest remained intact during the height of the global coffee crisis. I document how smallholders maintained historic agro-ecological spaces in the wake of destabilizing economic reforms. I argue cultural identity and access to new livelihood options combine to subsidize reproduction of coffee forests on the landscape.     

水稻种子贮藏谷蛋白的改良电泳分析法

利用15％－25％丙烯酰胺梯度凝胶的SDS－PAGE分析法可将水稻种子贮藏谷蛋白分离为3个酸性（α）亚基和3个碱性（β）亚基,通过调节两性电解质比例对现有等用点了和焦电泳分析法进行改良,可将谷蛋白酸性亚基和碱性亚基分别分划为13和14条多肽带,将上述两种方法结合起来的双向电泳分析法可以高清晰度地离析谷蛋白并获得单一多肽,此改良的电泳分析系统有助于确定水稻谷蛋白变异及谷蛋白的生化研究。     

An Exploration of Chronotones: A Concept for Understanding the Health Processes of Changing Ecosystems

The concept of ecotones as representing the boundary between two ecosystems has proved useful, not only in ecology but also in the epidemiology of zoonoses and vector-borne diseases. The ecotone is a boundary in space between two ecosystems in which many complex processes are at work. Under conditions of man-made environmental change, there are analogous boundaries in time between the two ecosystems or landscape phases. For example, between arid land and the presence of an irrigation scheme, there is the damming of a river and construction phase. Between forest and the grassland into which it may be converted is the process of deforestation; and between countryside and the townscape into which it may be changed is the urbanization process. Many epidemiological events may occur during these relatively short periods of rapid change over time, for which we propose the term chronotones. Examples are given of the epidemiological importance of chronotones and of the need to distinguish this more rapid transitional phase from the ecosystems that precede and follow the changes. A chronotone can be viewed both as an interface and as a special period in its own right. Epidemiologically, it carries risks peculiar to itself combined with some health risks of the preceding and following stages, and also opportunities for actions which can have far-reaching benefits to health in the next phase. The chronotone may need greater health-directed expenditure and effort than other periods, but with disproportionately greater total benefits in the short and longer term.     

Primate Seed Dispersal and Forest Restoration: An African Perspective for a Brighter Future

Primate seed dispersal is a vital, but complex, ecological process that involves many interacting agents and plays important roles in the maintenance of old-growth forest, as well as in the development of regenerating forest. Focusing primarily on African examples, in this article we briefly review the ecological process of primate seed dispersal, highlighting understudied and contentious topics, and then we discuss how our knowledge on primate seed dispersal can promote both forest restoration and primate conservation. Though it is frequently claimed that primates are critically important for the maintenance of diverse tropical forest ecosystems, we believe that more empirical evidence is needed to support this claim. Confounding factors can often be difficult to rule out and long-term studies extending beyond the seedling or sapling stage are very rare. In addition, though primates are critical for initial seed dispersal of many tree species, spatial and temporal variation in post-deposition processes, such as secondary seed dispersal and predation by rodents, can dramatically alter the initial patterns generated by primates. However, given the need for immediate conservation action to prevent further primate extinctions, we advocate that the knowledge about primate seed dispersal be used in formulating informed conservation plans. One prominent area where this knowledge will prove extremely valuable is in forest restoration efforts. To aid in the development of such efforts, we pose five questions, the answers to which will help facilitate forest restoration becoming a useful tool in strategies designed to conserve primates.     

Maintaining Research Integrity While Balancing Cultural Sensitivity: A Case Study and Lessons From the Field

Contemporary emphasis on creating culturally relevant and context specific knowledge increasingly drives researchers to conduct their work in settings outside their home country. This often requires researchers to build relationships with various stakeholders who may have a vested interest in the research. This case study examines the tension between relationship development with stakeholders and maintaining study integrity, in the context of potential harms, data credibility and cultural sensitivity. We describe an ethical breach in the conduct of global health research by a arising from the ad‐hoc participation of a community stakeholder external to the visiting research group. A framework for reflection is developed from a careful examination of underlying factors and presented with a discussion of consequences and mitigation measures. This framework aims to present lessons learned for researchers working abroad who might face similar situations in their work.     

水稻种子贮藏谷蛋白的微细异质性

利用灵敏的等聚焦与SDS－PAGE合的双向电泳分析方法,从水稻（Oryza sativa L.)种子贮藏谷蛋白中至少可以分离为13条酸性和19条碱性多 肽,依据谷蛋白多肽的表现量推测,水稻谷蛋白主要由约6个主效基因控制,肽图谱与N－端氨基酸序列分析可清晰将谷蛋白酸性多肽分为两组,此两组恰好与谷蛋白GluA和GluB两个cDNA克隆组相吻合。     

Far-red Sensitive Dark Processes Essential for Light- and Gibberellin-induced Germination of Lettuce Seed

The action of prolonged far-red on seed germination was studied in Lactuca sativa L. var. Grand Rapids. Exposure of imbibed seeds to 6 hours far-red before the application of gibberellic acid (GA₃) and thiourea completely prevented germination. Using GA₃, this far-red was effective after the sixth hour of imbibition. At 6, 12, and 18 hours of imbibition equal durations of far-red had equal effects. The kinetics of far-red action was investigated: it was found that although far-red for several hours, irrespective of the energy level, was needed for maximum inhibition, shorter durations (15 and 30 mins) were also appreciably effective provided they were followed by several hours darkness before the supply of GA₃. This is taken to indicate the existence of labile product(s) of the action of a far-red sensitive pigment. Evidence is provided for the existence of promotive dark processes controlled by this pigment, which are essential for germination whether triggered by GA₃, thiourea or red-light. A model for the operation of the pigment system is proposed and its role in the germination mechanism of this seed is discussed.     

Transgenic Rice: Characterization of Protoplastderived Plants and their Seed Progeny

Thirty eight green and 2 albino plants were regenerated from400 kanamycin-resistant colonies derived from protoplasts isolatedfrom cell suspensions of Oryza sativa variety Taipei 309 andelectroporated with pCaMVNEO carrying the neomycin phosphotransferaseII (nptII) gene. Twenty of the green transgenic R_o plants weretransferred to the glasshouse, where 3 flowered after 7 months.Of 15 plants analysed by DNA hybridization, all carried thenptll gene, but only 2 of 11 plants assayed for NPTII activityexpressed the nptll gene. One transgenic R_o plant produced 59seeds following self-pollination. The seeds, when germinatedon medium containing kanamycin sulphate, gave 16 green transgenicR, plants. Five transgenic R₁ plants flowered and set seed,7 flowered but failed to produce seeds, while 4 did not producepanicles. Transgenic R_o and R₁ plants were shorter, requiredlonger to flower, and had reduced pollen viability comparedto non-transformed R₁ protoplast-derived plants. The nptII genewas present in all 16 transgenic R₁ plants, but NPTII activitywas detected in only 8 of these plants. Key words: Oryza sativa variety Taipei 309, rice, protoplasts, direct DNA uptake, kanamycin-resistant tissues, transgenic plants, DNA hybridization, neomycin phosphotransferase II (NPTII), gene expression and inheritance     

Processes Maintaining Calcium Homeostasis in Acinar Cells of the Rat Submandibular Salivary Gland

Using a Ca²⁺-sensitive fluorescent indicator, fura-2/AM, we recorded calcium transients in secretory cells of isolated acini of the rat submandibular salivary gland; these transients were induced by hyperpotassium-induced depolarization (after an increase in [K⁺] _e up to 50 mM) of the plasma membrane of the above cells. Calcium transients were significantly suppressed by 50 M nifedipine. Addition of 10 M carbonyl cyanide m-chlorophenylhydrazone to the normal extracellular solution was accompanied by a rise in [Ca²⁺] _i , whereas when hyperpotassium solution is used the effect was less expressed. Blockers of CA²⁺-ATPase in the cellular membrane and in the endoplasmic reticulum, eosin Y (5 M) and cyclopiazonic acid (CPA, 5 M), respectively, evoked a significant increase in [Ca²⁺] _i and a decrease in the K⁺-depolarization-induced calcium transient. Extracellular application of caffeine (2, 10, or 30 mM) was accompanied by a concentration-dependent rise in [Ca²⁺] _i . Therefore, potassium depolarization of the plasma membrane of acinar cells of the rat submandibular salivary gland activates both the voltage-dependent Ca²⁺ influx and Ca²⁺-induced Ca²⁺ release from the endoplasmic reticulum; the initial level of [Ca²⁺] _i was restored at the joint involvement of Ca²⁺-ATPases in the plasma membrane and the membranes of the endoplasmic reticulum and mitochondria.     

Research Needs for Understanding and Predicting the Behavior of Managed Ecosystems: Lessons from the Study of Agroecosystems

Managed ecosystems are complex, dynamic systems with spatially varying inputs and outputs that are the result of interrelated physical, biological, and human decision-making processes. To gain an adequate understanding of these systems and predict their behavior, we believe that it is necessary to move beyond stylized theoretical models and loosely coupled disciplinary simulation models to what we describe as “fully integrated models.” Herein we present a conceptual framework for a more integrated approach to the study of managed ecosystems using the example of agricultural ecosystems. We then propose the implementation of a research agenda that fosters coordinated disciplinary research aimed at a better understanding and quantification of linkages across disciplinary models. Key research issues include the effects of spatial scale, the assessment of uncertainty in coupled models, and methods for collecting and analyzing spatially referenced data. Received 6 October 2000; accepted 10 April 2001.     

Dormancy in Rice Seed II: THE INFLUENCE OF COVERING STRUCTURES

Most of the dormancy in rice seed can be accounted for by theinhibitory influence of the husk, and most of the residual dormancyafter dehusking can be attributed to the inhibitory influenceof other covering structures—either the pericarp or testa,or both. It is shown that the rate of water absorption is thesame in dormant and non-dormant seeds and that dormant seedsare capable of absorbing sufficient water for germination. Thecovering structures therefore do not cause dormancy by restrictingthe entry of water. Removal of a small area of the husk breaks the dormancy of alarge proportion of the seeds; but for some seeds this treatmentis ineffective whereas removal of the entire husk would breakdormancy. The site of the excision of a small area of the huskcan alter the effectiveness of the treatment: removal of a portionof husk immediately over the embryo is no more effective thanexcising a similar portion nearby, but the removal of part ofthe husk some distance from the embryo is not as effective.Sealing the perforations with paraffin wax has little effectexcept when carried out as soon as possible after the excisionis made, and then only in positions distant from the embryo. Attempts to extract a water-soluble or ether-soluble germinationinhibitor from the husk and other parts of dormant seed or todemonstrate the presence of inhibitors by indirect methods havenot been successful. Nor has it been found possible to extracta water-soluble germination stimulator from seed which has brokendormancy. The implications of these results are discussed.     

Thermal Hardening: A New Seed Vigor Enhancement Tool in Rice

In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.     

Rice Aldehyde Dehydrogenase7 Is Needed for Seed Maturation and Viability

Aldehyde dehydrogenases (ALDHs) catalyze the irreversible oxidation of a wide range of reactive aldehydes to their corresponding carboxylic acids. Although the proteins have been studied from various organisms and at different growth stages, their roles in seed development have not been well elucidated. We obtained T-DNA insertional mutants in OsALDH7, which is remarkably inducible by oxidative and abiotic stresses. Interestingly, endosperms from the osaldh7 null mutants accumulated brown pigments during desiccation and storage. Extracts from the mutant seeds showed a maximum absorbance peak at 360 nm, the wavelength that melanoidin absorbs. Under UV light, those extracts also exhibited much stronger fluorescence than the wild type, suggesting that the pigments are melanoidin. These pigments started to accumulate in the late seed developmental stage, the time when OsALDH7 expression began to increase significantly. Purified OsALDH7 protein showed enzyme activities to malondialdehyde, acetaldehyde, and glyceraldehyde. These results suggest that OsALDH7 is involved in removing various aldehydes formed by oxidative stress during seed desiccation. The mutant seeds were more sensitive to our accelerated aging treatment and accumulated more malondialdehyde than the wild type. These data imply that OsALDH7 plays an important role in maintaining seed viability by detoxifying the aldehydes generated by lipid peroxidation.The major regulatory factors that control seed aging are oxidative stress, lipid peroxidation, and respiration (Sun and Leopold, 1995; Bailly et al., 1996; Akimoto et al., 2004). Lipid peroxidation and respiration result in the formation of reactive aldehydes such as malondialdehyde (MDA) and acetaldehyde, which tend to react with proteins and amino acids (Mueller, 1998; Almeras et al., 2003; Weber et al., 2004). Those reactions cause aging and seed damage (Zhang et al., 1995, 1997). Until recently, a physiological approach has been taken in research on seed aging, and molecular and genetic studies have been seldom reported (Clerkx et al., 2004a).Rice (Oryza sativa) is an important food crop, especially in Asia. Although stress tolerance has been extensively evaluated in an effort to develop advanced cultivars, the aging of seeds is an important economic problem that has been rarely examined (Devaiah et al., 2007). Their deterioration by lipid peroxidation leads to undesirable taste, color, and odor (Robertson et al., 1973; Nakayama et al., 1981; List et al., 1992). This is caused by various reactive aldehydes containing MDA, which are volatile aromatic compounds. Those aldehydes also bind with proteins and amino acids nonenzymatically, resulting in the accumulation of brown pigments during seed storage (Sun and Leopold, 1995).Aldehydes are intermediates in several fundamental metabolism pathways for carbohydrates, vitamins, steroids, amino acids, and lipids (Yoshida et al., 1998). They are also produced in response to environmental stresses that disturb metabolism, including salinity, dehydration, desiccation, cold, and heat shock (Bartels, 2001). Although indispensable for an organism, excessive amounts threaten seed survival because of their chemically reactive nature and the toxic effect of the molecules (Lindahl, 1992). Therefore, aldehyde levels in cells must be regulated tightly.Aldehyde dehydrogenases (ALDHs) are represented by a protein super-family that can be categorized into 21 families in eukaryotes (Perozich et al., 1999; Sophos et al., 2001; Sophos and Vasiliou, 2003; Fong et al., 2006). Some ALDHs are substrate specific while others have a highly variable substrate specificity (Sophos and Vasiliou, 2003). ALDHs catalyze the irreversible oxidation of a wide range of reactive aldehydes to their corresponding carboxylic acids (Perozich et al., 1999; Kirch et al., 2005). Therefore, they play a pivotal role in detoxifying the aldehydes generated by environmental stresses. Plant enzymes are represented in 11 ALDH families (Kirch et al., 2004). Despite their importance, the physiological functions of ALDHs in plants have rarely been studied (Liu et al., 2001; Liu and Schnable, 2002; Sunkar et al., 2003; Tsuji et al., 2003).Family 7 ALDHs (antiquitins) are comparatively distinguishable from other ALDH families, because they show low sequence identity (approximately 30%) to ALDHs from other families (Vaciliou et al., 1999). However, the amino acid sequences among Family 7 members are highly homologous (about 60%–70%; Lee et al., 1994; Fong et al., 2006). In contrast to animal antiquitins that do not exhibit any inducible response to stresses (Lee et al., 1994; Fong et al., 2006), antiquitin in garden pea (Pisum sativum) is inducible by dehydration (Guerrero et al., 1990).Overexpression of Arabidopsis (Arabidopsis thaliana) and soybean (Glycine max) ALDH7 confers tolerance to osmotic and oxidative stresses in transgenic plants (Kotchoni et al., 2006; Rodrigues et al., 2006). Moreover, their MDA and hydrogen peroxide contents are decreased. This suggests that ALDH7s function not only as aldehyde-detoxifying enzymes but also as efficient scavengers of reactive oxygen species and as lipid peroxidation-inhibiting enzymes.In this study, we used null mutants in the rice ALDH7 gene to investigate the functional roles of ALDH7 during seed development and storage.