果树中糖类代谢和调控研究

糖是生物体内主要的碳源,是光合作用的主要产物,可为生物体提供能量,在植物的生长发育过程中起重要作用。本文综述了近年来关于糖类与果树生长发育及品质形成方面的相关研究进展,重点介绍了糖类运输、积累与基因表达、糖信号传导和糖类调控网络等方面的研究进展,并对今后利用分子生物学手段进行果实品质改良等方面的研究方向进行了展望。     

Nutrient reserves in roots of fruit trees,in particular carbohydrates and nitrogen

Summary In trees, nutrient reserves built up in the previous year are of primary importance for early spring growth. Despite the relatively great importance of roots for nutrient storage, the root system should not be regarded as a special storage organ. Quantitatively, carbohydrates predominate in these reserves, but qualitatively N and other minerals are of more than minor significance. In roots carbohydrates are usually stored in insoluble form, mainly as starch; sorbitol is the predominant soluble compound in apple and peach. For nitrogen reserves, the soluble form predominates in roots, especially arginine in apple and peach, followed by asparagine. The level of reserves usually becomes maximal early in the winter. During leafing-out the reserves are drawn on until, later in the season, the supply of newly produced or absorbed nutrients exceeds the demand and replenishment occurs. The initial carbohydrate reserves do not determine the amount of new growth, whereas reserve nitrogen is of decisive importance for shoot growth vigour. Environmental factors such as light intensity and temperature affect the level of carbohydrates in roots; the concentration can be reduced by defoliation and summer pruning and increased by ample supply of nitrogen fertilizer in the autumn. The main cultural factors that influence nitrogen reserves are the amount and the time of nitrogen fertilization.     

Male reproductive traits, semen cryopreservation, and heterologous in vitro fertilization in the bobcat (Lynx rufus)

There is limited information on bobcat ejaculate traits and sperm cryopreservation and fertilizing ability. Bobcats were electroejaculated under general anesthesia in November (autumn) and April (spring), and endocrine and sperm traits were characterized. Testosterone (mean ± SEM: 0.90 ± 0.15 ng/mL) was not different between sampling times, but cortisol (average: 13.95 ± 1.73 μg/dL) was significantly higher in April. Average number of spermatozoa was 10.0 ± 3.4 × 10⁶ sperm/ejaculate, with values being significantly higher in April. Sperm motility (average 55.7 ± 5.8% motile sperm) was not different between sampling times. The proportion of normal spermatozoa in the ejaculate (average: 14.7 ± 2.1%) was significantly higher in April, but the percentage of spermatozoa with intact acrosomes (average: 43.7 ± 3.8%) was significantly higher in autumn. Spermatozoa were cryopreserved in a Tes-Tris-based diluent (TEST) or Biladyl, both containing 20% egg yolk and 4% glycerol. Diluted sperm were loaded into straws, refrigerated using a programmable thermoblock with a dry chamber, frozen in nitrogen vapors, thawed, and incubated in F-10 medium with 5% fetal bovine serum for up to 3 h. After cryopreservation in TEST, there were about 50% motile sperm upon thawing, and survival was high during incubation post-thaw. Cryopreservation in Biladyl led to similar results, but motility decreased substantially during incubation post-thaw. Bobcat spermatozoa fertilized domestic cat oocytes matured in vitro. Fertilization rates were higher for sperm collected in April and cryopreserved in TEST (46%) than for those cryopreserved using Biladyl (<3%). Fertilized oocytes cleaved in culture, and some (27%) reached the morula stage. This study has allowed us to gain further baseline information on bobcat reproduction, explore sperm cryopreservation conditions, and show that fertilizing capacity can be tested using in vitro-matured cat oocytes. These results will be important for future conservation efforts.     

Efficient germ-line transformation of the economically important pest species Lucilia cuprina and Lucilia sericata (Diptera, Calliphoridae)

The green blowfly species Lucilia cuprina and Lucilia sericata are economically important pests for the sheep industries of Australia and New Zealand. L. cuprina has long been considered a good target for a genetic pest management program. In addition, L. sericata maggots are used in the cleaning of wounds and necrotic tissue of patients suffering from ulcers that are difficult to treat by other methods. Development of efficient transgenesis methods would greatly facilitate the development of strains ideal for genetic control programs or could potentially improve “maggot therapy”. We have previously reported the germ-line transformation of L. cuprina and the design of a “female killing system” that could potentially be applied to this species. However, the efficiency of transformation obtained was low and transformed lines were difficult to detect due to the low expression of the EGFP marker used. Here we describe an efficient and reliable method for germ-line transformation of L. cuprina using new piggyBac vector and helper plasmids containing the strong promoter from the L. cuprina hsp83 gene to drive expression of the transposase and fluorescent protein marker gene. We also report, for the first time, the germ-line transformation of L. sericata using the new piggyBac vector/helper combination.     

Laboratory evaluation of the chemosterilant lufenuron against the fruit flies Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons

Four species of tephritid fruit flies, Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons were evaluated for toxic, developmental, and physiological responses to the chemosterilant lufenuron. No significant mortality of laboratory strains of the first three species was observed after their exposure up to 50 μg/mL of lufenuron in agar adult diet, whereas B. latifrons adults fed with 50 μg/mL of lufenuron in the diet caused significant mortality compared to the control. Fertility of C. capitata adults fed on 50 μg/mL lufenuron-fortified diet between 7 and 12 days of age was approximately 46% of the no lufenuron control. Fertility of B. dorsalis and B. latifrons adults fed on 50 μg/mL lufenuron-incorporated diet was about 45% and 62% of the control, respectively. Lufenuron did not significantly affect fertility of B. cucurbitae adults. Lufenuron did not affect fecundity of C. capitata and B. dorsalis. Fecundity of B. cucurbitae and B. latifrons was not evaluated due to difficulty to count the eggs laid deep in the agar diet. Larvae fed on a liquid larval diet with ≤ 0.1 μg/mL of lufenuron were also evaluated. Pupal recovery, adult emergence, adult fliers, mating, egg hatch, and egg production of C. capitata were significantly decreased, while for B. dorsalis, pupal recovery, larval duration and adult emergence were affected. No effect of lufenuron on B. cucurbitae larvae was observed. B. latifrons was not performed because shortage of eggs at the time of this research. Lufenuron is a potential agent for management and control of C. capitata and B. dorsalis.     

Seasonal effects on thermoregulatory abilities of the Wahlberg's epauletted fruit bat (Epomophorus wahlbergi) in KwaZulu-Natal,South Africa

Seasonal variations in ambient temperature (T_a) require changes in thermoregulatory responses of endotherms. These responses vary according to several factors including taxon and energy constraints. Despite a plethora of studies on chiropteran variations in thermoregulation, few have examined African species. In this study, we used the Wahlberg's epauletted fruit bat (Epomophorus wahlbergi, body mass≈115 g) to determine how the thermoregulatory abilities of an Afrotropical chiropteran respond to seasonal changes in T_a. Mass specific Resting Metabolic Rates (RMR_Ta) and basal metabolic rate (BMR) were significantly higher in winter than in summer. Furthermore, winter body mass was significantly higher than summer body mass. A broad thermoneutral zone (TNZ) was observed in winter (15–35 °C) compared with summer (25–30 °C). This species exhibited heterothermy (rectal and core body temperature) during the photophase (bats' rest-phase) particularly at lower T_as and had a low tolerance of high T_as. Overall, there was a significant seasonal variation in the thermoregulatory abilities of E. wahlbergi. The relative paucity of data relating to the seasonal thermoregulatory abilities of Afrotropical bats suggest further work is needed for comparison and possible effects of climate change, particularly extreme hot days.     

陕北沙地小叶杨“小老树”的水力适应性

以黄土高原"小老树"发生面积最大的树种-小叶杨为例,研究了不同水分生境下(水分相对好的沟道和干旱的梁坡片沙地,分别标记为生境A和生境B)小叶杨的生长、光合、水力学特性等,试图探讨小叶杨"小老树"对干旱生境的适应机制。结果表明:生境B小叶杨树高、地径、1 m树高处直径明显小于生境A,同时其主茎顶端枯枝长度大于生境A;生境B小叶杨叶净光合速率和气孔导度明显低于生境A。两种生境下小叶杨黎明前和正午叶水势无显著差异,生境B小叶杨正午时小枝枝干的比导水率明显低于生境A,但两种生境的比叶导水率则无显著差异,生境B小叶杨的Huber值明显大于生境A。生境B小叶杨枝干的P50(导水率损失50%时所对应的木质部水势)比生境A低约0.76 MPa左右,其气孔关闭的水势比生境A晚0.2 MPa左右,生境B小叶杨水分传输安全距离明显大于生境A。表明干旱生境下小叶杨高Huber值和低气孔导度有助于其叶水分关系维持相对稳定,低光合速率和维持大的水分传输安全距离所需的木质部碳投资增加是小叶杨形成"小老树"的重要原因。     

Gamete cryobanks for laboratory research: Developing a rapid and easy-to-perform protocol for the cryopreservation of the sea urchin Paracentrotus lividus (Lmk, 1816) spermatozoa

Gamete cryopreservation is a biotechnology that can guarantee a continuous supply of gametes, regardless of the seasonal reproductive cycle. In this study we developed a protocol for the cryopreservation of the sea urchin Paracentrotuslividus spermatozoa, with a view to the creation of cryobanks of semen to be used as a model system in laboratory research and ecotoxicological tests. All the key phases of the procedure were separately considered and the effect on sperm motility was evaluated by means of computer assisted analysis. The best results were obtained using 7% dimethylsulfoxide in 1% NaCl plus 0.04 M trehalose as the extender, at a freezing rate of −20 °C/min. On thawing, in semen samples cryopreserved in accordance with this protocol the velocity parameters of the sub-population of rapid sperm (best performing spermatozoa) did not significantly differ from semen on collection; in addition also the fertilization ability was restored, and about 50% of normal developed plutei larvae were obtained by thawed semen. The developed protocol is rapid and easy-to-perform; moreover, the use of gametes from reared urchins makes it unnecessary to continuously collect specimens from natural populations, making this procedure a promising starting point for the creation of alternative and more sustainable methodologies in laboratory research on sea urchin gametes and embryos.     

Expression profiling of the triterpene saponin biosynthesis genes FPS, SS, SE, and DS in the medicinal plant Panax notoginseng

Panax notoginseng (Burk) F. H. Chen, an economically significant medicinal plant with hemostatic and health tonic activities, has been used in Traditional Chinese Medicine (TCM) for more than 3000 years. Triterpene saponins are responsible for most of the pharmacological activities of P. notoginseng. Here, we cloned five cDNA sequences encoding the key enzymes involved in triterpene saponin biosynthesis, namely, PnFPS, PnSS, PnSE1, PnSE2, and PnDS, and analyzed the conserved domains and phylogenetics of their corresponding proteins. Their organ-specific expression patterns in four-year-old P. notoginseng were detected by real-time PCR, showing that they were all most highly expressed in flowers. In addition, four of the genes, excluding PnSE2, were upregulated in leaves following stimulation with methyl jasmonate. This study is the first comprehensive analysis of the expression patterns of pivotal genes for triterpene saponin biosynthesis in P. notoginseng and provides a basis to further elucidate the molecular mechanism for the biosynthesis of these medically important compounds.     

Biotechnological advances in the diagnosis,species differentiation and phylogenetic analysis of Schistosoma spp.

Schistosomiasis is a serious parasitic disease caused by blood-dwelling flukes of the genus Schistosoma. Throughout the world, schistosomiasis is associated with high rates of morbidity and mortality, with close to 800 million people at risk of infection. Precise methods for identification of Schistosoma species and diagnosis of schistosomiasis are crucial for an enhanced understanding of parasite epidemiology that informs effective antiparasitic treatment and preventive measures. Traditional approaches for the diagnosis of schistosomiasis include etiological, immunological and imaging techniques. Diagnosis of schistosomiasis has been revolutionized by the advent of new molecular technologies to amplify parasite nucleic acids. Among these, polymerase chain reaction-based methods have been useful in the analysis of genetic variation among Schistosoma spp. Mass spectrometry is now extending the range of biological molecules that can be detected. In this review, we summarize traditional, non-DNA-based diagnostic methods and then describe and discuss the current and developing molecular techniques for the diagnosis, species differentiation and phylogenetic analysis of Schistosoma spp. These exciting techniques provide foundations for further development of more effective and precise approaches to differentiate schistosomes and diagnose schistosomiasis in the clinic, and also have important implication for exploring novel measures to control schistosomiasis in the near future.     

Highly differentiated populations of the narrow endemic and endangered species Primula cicutariifolia in China,revealed by ISSR and SSR

The perennial herb Primula cicutariifolia Pax is an endangered and endemic species with narrow distribution in eastern Anhui and Zhejiang provinces of China. In this study, the levels of genetic variation and the pattern of genetic structure in five natural populations of P. cicutariifolia were assessed by inter-simple sequence repeats (ISSR) and simple sequence repeat (SSR) markers. Both markers revealed that there was remarkably low genetic variation within populations (e.g., H_e = 0.19 and 0.18, for ISSR and SSR respectively) and high differentiation among populations (G_ST = 0.714 and 0.611; Φ_ST = 0.698 and 0.599, for ISSR and SSR respectively). The level of population genetic diversity was correlated to population size only detected by ISSR markers. The genetic structure of P. cicutariifolia may be explained by limited gene flow that was caused by habitat fragmentation and limited seeds and pollen dispersal ability, self breeding system and biennial life form. To protect and avoid disappearance of P. cicutariifolia, much more attentions should be paid to protect all the remnant populations and their habitats, and three management units, i.e. Tianmushan, Damodao, and Panan units, were proposed.     

Gene flow and genetic structure of Sicyopterus lagocephalus in the south-western Indian Ocean, assessed by intron-length polymorphism

Sicyopterus lagocephalus is the most abundant sicydiine (amphidromous gobiid) in the rivers of volcanic islands in the south-western Indian Ocean. The species occurs in the Mascarene (Mauritius and La Réunion) and Comoros islands (Anjouan, Mayotte, etc.) and the post-larvae supply an economically important fishery. Because of the scarcity of available ecological and biological data, a genetic survey has been undertaken at the scale of the south-western Indian Ocean using intron-length polymorphism. Samples from La Réunion, Mauritius and Mayotte were used to assess the population genetic structure within islands and between nearby and remote islands. No genetic divergences were observed in samples at these different geographical scales. A lower number of rare alleles were observed in Mayotte samples suggesting a slight effect of their peripheral geographical position. However, no recent bottleneck was evidenced for these populations. High temporal divergences have been demonstrated in La Réunion as in previous studies indicating a temporal Wahlund effect. In the light of these results, the dispersion abilities, the connectivity of populations and the metapopulation functioning are discussed in relation to the regional environmental factors (dispersal barriers, habitat colonization, cyclones, long distance dispersal).     

Population structure and genetic diversity of Stipa grandis P. Smirn,a dominant species in the typical steppe of northern China

Random amplified polymorphic DNA (RAPD) markers were used to characterize genetic heterogeneity within and among five populations of Stipa grandis in the Xilingol Plateau. Estimates of the percentage of polymorphic bands, Shannon's diversity information index and Nei's gene diversity index were comparatively high in the five populations, and the Population GSM was found to have the highest genetic diversity among all populations. An analysis of molecular variance indicated that the majority of variation existed within populations (74.12%), and that there was significant differentiation among populations (Φ_ST = 25.88%, P < 0.001). Genetic distance (Φ_ST) ranged from 0.198 to 0.310 and the differentiation between pair-wise populations was significant when individual pairs of populations were compared. Based on the Φ_ST values, gene flow (Nm) was estimated and was found to vary from 0.556 to 1.013 between pair-wise populations and 0.7412 among populations. The results of UPGMA cluster analysis and nonmetric multi-dimensional scaling analysis indicated that most variation occurred within populations and that genetic differentiation had happened between populations. These findings are important for a better understanding of the adaptive strategy of S. grandis in northern China and will be useful for conservation managers to work out an effective strategy to protect this important species.     

Comparison of biological and conventional insecticide treatments for the management of the pineapple fruit borer, Strymon megarus (Lepidoptera: Lycaenidae) in Costa Rica

Carbaryl is currently one of the most commonly used insecticides for the control of the pineapple fruit borer, Strymon megarus (Godart), in commercial pineapple production. To evaluate more sustainable biological alternatives to conventional insecticides, three microbial and one botanical insecticide were studied. Beauveria bassiana, Metarhizium anisopliae, Bacillus thuringiensis (Bt) and a plant extract from Quassia amara were compared with carbaryl in replicated field trials in Costa Rica during 2005 and 2006. In both years of testing, the untreated control received over 50% fruit damage from S. megarus. Bt and carbaryl provided the highest level of control and the lowest level of fruit damage compared to all other treatments. Based on the results of this study, Bt appears to be an acceptable biological alternative to the conventional insecticide (carbaryl) for control of S. megarus on pineapple. In addition, Bt was the least expensive treatment used in this study.     

Ice-age isolation,postglacial hybridization and recent population bottlenecks shape the genetic structure of Meum athamanticum in Central Europe

Phylogeographic analyses can help to reveal the refugial structure of plants during and after the ice ages, but the detailed history of regional refugial isolation and differentiation in Central Europe is still poorly understood. A recent study of Meum athamanticum in its total range of occurrences revealed persistence of this temperate montane plant species in Central Europe north of the Alps, without going into details. We therefore aimed to study differentiation and migration processes of this plant species in more detail throughout Central Europe. We used high resolution amplified fragment length polymorphisms (AFLP) markers and analyzed 210 plant individuals of 14 Central European populations with three pairs of primer combinations (128 loci, 111 of which polymorphic). The data show genetic differentiation and varying levels of molecular diversity within populations and groups of populations. Altogether, the studied populations did not show a gradient in molecular variation along presumptive postglacial migration routes across Central Europe. Rather, they reveal a genetic division into seven major groups. Four of them are characterised by high genetic diversity, private fragments and higher than average number of rare and sparse fragments, leading to the assumption that they are descendants of independent populations which survived in glacial refugia. In combination with information from paleoclimate and paleovegetation, it is likely that microclimatically favoured habitats at (i) the eastern flank of the Black Forest, (ii) the southern margin of the Cologne basin, (iii) the foothills of the Erzgebirge, and (iv) the foothills of the Jura Mountains acted as sources for the postglacial recolonisation of this species to the other mountains of Central Europe. As some of the populations analysed show intermixed gene-pools (i.e. including genetic information from different groups) and partly have exceptionally high genetic diversity, but no private and only relatively few rare or sparse fragments, they might represent contact zones. On the other hand, genetic pauperization and isolation of two other populations in connection with extremely small population sizes and unfavourable habitat conditions seem to reflect recent bottlenecks. Consequently, the genetic structure of M. athamanticum in Central Europe is shaped by (i) extra-Mediterranean glacial refugia in situ, (ii) following postglacial hybridization along emerging contact zones and (iii) genetic bottlenecks in thereafter isolated small populations. All results provide evidences for small scale migration of the species between Central European valleys and surrounding highlands. Therefore, our study provides molecular evidence for both climate dependent wide ranging periglacial tabula rasa, but some small refugia in locally buffered areas. We hereby show that the environmental heterogeneity of cold stage landscapes in Central Europe is generally underestimated.     

Effect of age and mating on pheromone production in the female olive fruit fly, Dacus oleae (Gmel.)

Virgin female olive fruit flies began producing sex pheromone on the third day after emergence. Production of sex pheromone appears to be cyclical with peaks of production recurring at about 10-day intervals, each peak lasting 2–3 days. As the female ages, the quantity of sex pheromone produced during the period of high pheromone production decreases, but it is always higher than the quantity present in the pheromone gland during the rest of female life.Mated females produced less sex pheromone the first 10 days after mating which then increased to near the same level of that in virgin females.     

Microsatellite analysis reveals the genetic structure and gene flow of the aquatic quillwort Isoetes sinensis, a critically endangered species in China

Isoetes sinensis is a critically endangered aquatic quillwort, occurring in two fragmented sites of China (Xiuning county of Anhui; Jiande county of Zhejiang). During a five-year period (2004-2009), the areas and sizes of the two populations diminished dramatically due to intensive human activities. Genetic structure of the species was investigated using simple sequence repeat makers (SSRs). For seven nuclear microsatellites, high levels of genetic diversity were found within populations (H_E = 0.324-0.447). Strong genetic differentiation was detected between populations (G_ST = 0.376), while weak genetic differentiation was found within populations (G_ST = 0.026-0.080). Notably, in contrast to the source-sink model suggested by previous study (Chen et al., 2009), the migration pattern of I. sinensis along the Xin’an River is best explained by the linear symmetrical non-adjacent flow model (LSNF), which indicates that intensive human activities of recent years have greatly affected the gene exchange pattern among I. sinensis subpopulations.     

云南元江芒果园桔小实蝇成虫日活动规律及空间分布格局

利用甲基丁香酚引诱剂和黄板对桔小实蝇Bactrocera dorsalis成虫日活动规律及飞行高度进行了研究,同时根据多种聚集度指标对桔小实蝇成虫的空间分布格局进行了分析。结果表明:元江县挂果期芒果园内桔小实蝇日活动量高峰出现在10:00、16:00左右,活动量低谷出现在8:00、14:00和19:00左右,日间温湿度与其日活动量之间无线性相关关系;成虫飞行高度随时间变化,受降雨影响,雌雄成虫飞行高度存在差异。上午、中午成虫多近地飞行,午后多在1.5 m以上高度飞行,降雨导致成虫飞行活动量大幅减退,多分布于1.5 m以上枝叶附近。株高8 m的3a芒果树4 m高度处黄板捕获虫量最大,其次是2 m高处,6m以上虫量较少。雄性成虫在芒果园中呈聚集分布,原因之一是其自身的聚集行为;雌虫空间分布不均,主要呈聚集分布,少数部分为均匀分布,其聚集由环境因素造成。