Incompatibility behavior of a symbiotic plasmid pMH7653Rb in <Emphasis Type="Italic">Mesorhizobium huakuii</Emphasis> 7653R

Mesorhizobium huakuii strain 7653R harbored two indigenous plasmids named pMH7653Ra and pMH7653Rb. The larger plasmid pMH7653Rb (symbiotic plasmid) was transferred to M. huakuii HN308SR harboring three plasmids: pMHHN308a, pMHHN308b and pMHHN308c, and HN3015SR harboring three plasmids: pMHHN3015a, pMHHN3015b and pMHHN3015c by tri-parent mating. Two stable indigenous plasmids, pMHHN308b and pMHHN308c of HN308SR, were co-eliminated due to the introduction of pMH7653Rb, and the transconjugant was named HN308SRN14. The results implied that pMH7653Rb and pMHHN308b, pMHHN308c were incompatible and might have been ascribed to the same incompatible group. The plasmid profiles of transconjugant HN3015SRN14 showed that the second largest plasmid pMHHN3015b of HN3015SR was cured due to the introduction of pMH7653Rb. The results also implied that pMH7653Rb and pMHHN3015b were incompatible. Results from plant nodulation tests showed that pMH7653Rb could only maintain the nodulation ability in transconjugant HN308SRN14 and its nodule number was more than that of wild strain HN308SR, but could not replace the nitrogen fixation effect of pMHHN308b and pMHHN308c. The plasmid cured mutant HN308SRN14D harboring only pMHHN308a formed null nodules that demonstrated pMHHN308a was relevant to nodulation ability. HN3015SRN14 harboring pMH7653Rb, pMHHN3015a and pMHHN3015c formed null nodules while HN3015SRN14D containing pMHHN3015a and pMHHN3015c lost the nodulation ability. The plasmid replication repC-like gene sequences were detected by a polymerase chain reaction from 7653R, HN308, HN3015, HN308SRN14 and HN3015SRN14. The repC gene sequence similarities of the strains tested attained 99%.     

Edible wild plants of the Chorote Indians, Gran Chaco, Argentina

The Chorote Indians are hunter-gatherers and fishermen from north-west Argentina and south-west Paraguay who belong to the Mataco-Maká linguistic family. Their edible plants are identified by botanical and vernacular names, the parts employed and modes of preparation and consumption. The Chorote people use 57 plant species as a source of food, which they consume in 118 different ways. Five new edible species, that yield seven plant foods, are reported here for the first time for Chaquenian ethnic groups. However, only a few wild plant foods are in frequent use today, with most being used occasionally, infrequently or not at all. A cross-cultural comparison with four neighbouring ethnic groups reveals that one third of their plant foods are exclusive to the Chorote people, despite the fact that they share most of their edible plants with the other groups. This article is the first contribution to an understanding of the Chorote's ethnobotany and to a comparison of interethnic relationships concerning their edible plant resources.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 73–85.     

Composition and distribution of indigenous trees and shrubs as possible criteria for indicating adapted species in semi‐arid rangelands

This study assessed the composition and natural distribution of indigenous trees and shrubs as possible criteria for selecting suitable species for rehabilitation of degraded sites in semi‐arid rangelands. Study sites were identified at Nthangu, Kathonzweni and Kibwezi forests of Makueni County, Kenya using existing vegetation, agro‐climatic maps and Landsat imageries. The sites had mean annual rainfalls of 974 mm, 700 mm and 616 mm, respectively, and moisture indices of 49%, 35% and 32%. Data were collected by establishing sample plots and assessing species counts and diameters at breast height (DBH). Basal area, relative dominance, relative abundance, relative frequency and important value indices (IVIs) were computed for individual families and species at each site. The number of families, genera and species declined from Nthangu (33, 60, 77) through Kibwezi (30, 48, 70) to Kathonzweni (28, 42, 69). Corresponding mean basal areas were 16.7 m² ha^?1, 76.8 m² ha^?1 and 19.3 m² ha^?1. The families Combretaceae, Burseraceae and Mimosaceae were the most important and widely distributed. Based on ecological importance values, candidate species for rehabilitation of degraded sites at Nthangu, Kathonzweni and Kibwezi were Combretum molle and Acacia hockii; Combretum collinum, Commiphora campestris and Acacia tortilis; and Commiphora africana and A. tortilis, respectively.     

Recreational boating: a large unregulated vector transporting marine invasive species

Aim Recreational boating is arguably the largest unregulated vector for the introduction and spread of marine invasive species. Hull fouling communities have been recognized to harbour non‐indigenous species (NIS), but presence should not be equated with transport. In this study, we characterize the presence of NIS in hull fouling communities, determine if host vessels transport these species and evaluate the importance of recreational boating as a vector for introduction and spread. Location Coastal British Columbia (BC), Canada. Methods Dive surveys in BC marinas were conducted to record the presence of NIS and to estimate their per cent cover. In addition, a boater questionnaire survey was used to determine common travel and maintenance practices. These results were combined to investigate the potential for recreational boats to transport NIS. Results Nine NIS, including the highly invasive ascidians Styela clava and Botrylloides violaceus, and the macroalga Sargassum muticum, were found in hull fouling communities on recreational boats. Overall, per cent cover was generally low; however, niche areas were commonly fouled, even on active and otherwise clean boats. Fouling of niche areas was not related to either antifouling paint age or travel frequency, and fouling levels were highly variable among individual boats both within marinas and across regions. Main conclusions Recreational boating is a major vector contributing to the spread of marine invasive species. Our results indicate that recreational boats represent a high‐risk vector both for primary introduction and secondary spread of marine NIS and should be subject to vector management regulations.     

Do invasive species show higher phenotypic plasticity than native species and,if so,is it adaptive? A meta‐analysis

Do invasive plant species have greater phenotypic plasticity than non-invasive species? And, if so, how does this affect their fitness relative to native, non-invasive species? What role might this play in plant invasions? To answer these long-standing questions, we conducted a meta-analysis using data from 75 invasive/non-invasive species pairs. Our analysis shows that invasive species demonstrate significantly higher phenotypic plasticity than non-invasive species. To examine the adaptive benefit of this plasticity, we plotted fitness proxies against measures of plasticity in several growth, morphological and physiological traits to test whether greater plasticity is associated with an improvement in estimated fitness. Invasive species were nearly always more plastic in their response to greater resource availability than non-invasives but this plasticity was only sometimes associated with a fitness benefit. Intriguingly, non-invasive species maintained greater fitness homoeostasis when comparing growth between low and average resource availability. Our finding that invasive species are more plastic in a variety of traits but that non-invasive species respond just as well, if not better, when resources are limiting, has interesting implications for predicting responses to global change.     

哈茨木霉发酵液中肽类物质对豇豆土著根瘤菌竞争结瘤的影响

通过树脂吸附、离子交换、薄层层析、高效液相色谱系统以及紫外、质谱等分离、纯化和鉴别的方法,从哈茨木霉T2-16菌株发酵液中分离得到一种对豆科作物生长具促进作用的肽类物质。用该肽类物质对豇豆土著根瘤菌进行处理后,用AFLP技术研究了该物质对供试根瘤菌遗传稳定性和在土壤中竞争结瘤能力的影响。结果表明,传代次数和培养温度(28℃~36℃范围)对供试根瘤菌的遗传性状无明显影响,其AFLP指纹未发生明显变化;但经木霉肽类代谢产物处理后,根瘤菌竞争结瘤能力得到提高,为对照根瘤菌的1.53倍。     

A rhizobia strain isolated from root nodule of gymnosperm Podocarpus macrophyllus

Symbiotic nitrogen fixation of rhizobia and leguminous plants is considered as the most important biologic nitrogen fixation system on earth. Symbiotic nodulation of gymnosperm Podocarpus macro-phyllus and rhizobia has never been reported. In this study, 11 endophytic bacteria strains were isolated from root nodules of P. macrophyllus and its variation P. macrophyllus var. maki. The plant infection tests on these strains indicated that the isolated strains could be nodulated on P. macrophyllus plants, and weak nitrogenase activity of nodules was found in acetylene reduction method. According to the physiological and biochemical characteristics of the 11 strains, GXLO 02 was selected as the representative strain. 16S rDNA full-length sequence analysis of GXLO 02 confirmed that the representative strain GXLO 02 belongs to Rhizobium sp.     

Garden Game: Shifting Cultivation,Indigenous Hunting and Wildlife Ecology in Western Panama

Participatory research documented the hunting yields of 59 households in five neighboring indigenous villages in western Panama. These households captured 2,580 kg of game over 8 months, with 47% of the harvest coming from agricultural areas. The quantity of game captured in anthropogenic habitats is influenced by the hunting strategies employed. Only 25% of game captured during hunting trips was captured in agricultural areas, as opposed to 93% while “awaiting” and 65% using traps. Reliance on different strategies is in turn dependent on age, gender, and access to firearms. I argue that garden hunting is not a response to game depletion, but rather a productive activity that is complementary to broader cultural and economic patterns, and that simultaneously protects crops from animal predation. The creation of heterogeneous habitat mosaics through shifting cultivation has played a key role in the relationship between people and wildlife in the humid neotropics, leading to adjustments in both animal foraging patterns and indigenous hunting practices.     

Coppice Harvesting of Fuelwood Species on a South African Common: Utilizing Scientific and Indigenous Knowledge in Community Based Natural Resource Management

The limitations of Community Based Natural Resource Management (CBNRM) with respect to the difficulties of comparing local versus scientific knowledge categories within a bounded definition of ‘community’ were investigated by means of a study exploring local indigenous knowledge pertaining to harvesting technique, and the impact of soil and species type on the post-harvest coppice response of popular savanna fuelwood species, among rural inhabitants of the Bushbuckridge region of the Limpopo Province, South Africa. Soils and plants were evaluated chiefly in terms of their perceived ability to retain precipitation, making rainfall a driving force in local understanding of environmental productivity. Some indigenous knowledge showed an agreement with biological data, but overall the variability in responses, as well as the diverse scales at which indigenous and scientific knowledge is directed, were too great to allow for simplistic parallels between local ecological indices to be made. Indigenous environmental knowledge was underscored by the perceived symbolic link between environmental and social degradation. It is recommended that environmental managers incorporate indigenous knowledge as a component of a systems-level approach to natural resource management, where biological, cultural, economic, and symbolic aspects of natural resource use are nested within a broader ecosocial system. This approach to indigenous knowledge is offered as an alternative to the simple scientific evaluation that so often characterizes environmental management.