Vertebrate dispersal syndromes along the Atlantic forest: broad-scale patterns and macroecological correlates

Aim To assess the geographical variation in the relative importance of vertebrates, and more specifically of birds and mammals, as seed dispersal agents in forest communities, and to evaluate the influence of geographical and climatic factors on the observed trends. Location One hundred and thirty‐five forest communities in the Brazilian Atlantic forest. Methods We collected data on dispersal modes for 2292 woody species. By combining species × site with species × trait matrices, we obtained the percentages of endozoochory, ornithochory, mastozoochory and the mean fruit diameter for the local forest communities. We used Spearman's correlation to assess bivariate relationships between variables. Subsequently, we performed paired t‐tests to verify if variations in frequency of dispersal modes and mean fruit diameter were influenced by altitude or temperature. Then, we applied multiple linear regressions to evaluate the effect of geographical and climatic variables on variation in the relative frequency of dispersal modes and mean fruit diameter across communities. Results We found no consistent latitudinal or longitudinal trend in the percentage of vertebrate‐dispersed species, neither bird‐ nor mammal‐dispersed species along the Atlantic forest. Endozoochory was affected chiefly by annual mean rainfall, increasing towards moister sites. Forest communities located at higher altitudes had a higher percentage of bird‐dispersed species. Even when sites with identical values of annual mean temperature were compared, altitude had a positive effect on ornithochory. Conversely, we found a higher percentage of mammal‐dispersed species in warmer forests, even when locations at the same altitudinal belts were contrasted. Fruit diameter was clearly related to altitude, decreasing towards higher elevations. Main conclusions This is the first analysis of a large data set on dispersal syndromes in tropical forest communities. Our findings support the hypotheses that: (1) geographical variation in the relative number of fleshy fruit species is mainly driven by moisture conditions and is relatively independent of geographical location, and (2) broad‐scale trends in fruit size correspond to geographical variation in the relative importance of mammals and birds as seed dispersal agents at the community level.     

Major depression and recent physical or sexual abuse increase readmissions among high-utilising primary care patients

Objective To investigate whether current major depression and past physical/sexual victimisation is associated with recurrent general hospital admissions.Method Ninety-six inner-city primary care patients with a history of high medical service utilisation completed the PRIME-MD and the Abuse Assessment Screen; medical records were reviewed to assess reasons for re-hospitalisations. We compared hospitalisation rates over the preceding 12 months between those subjects with and without major depression and those with and without histories of abuse.Results Compared to non-abused subjects, patients with past-year abuse showed significantly increased past-year hospitalisations (3.2 versus 1.8, P = 0.007). Re-admissions were related to chronic disease management and were not because of acute physical effects of trauma. Analysis of variance revealed that major depressive disorder and past-year abuse history interacted to increase an association with re-admissions.Conclusions Past-year abuse was independently associated with increased hospital admissions. Psychological effects of recent abuse combined with depression may particularly increase rates of medical/surgical hospitalisations.     

犬蝠对不同浓度香蕉汁的选择

为了解犬蝠的嗅觉灵敏度,我们以6 只成年犬蝠对不同浓度的成熟香蕉汁和纯水对照的选择倾向和取食时间各进行了连续5 个夜晚的室内观察。香蕉汁的浓度分别为100% (120 g),50% (60 g 香蕉汁和60 g 纯水),25% (30 g 香蕉汁和90 g 纯水),12. 5% (15 g 香蕉汁和105 g 纯水);另取纯水(W)与熟烂的香蕉汁(OR)各120 g 作为对照。将以上食物和对照随机注入不同的容器内,观察犬蝠对不同浓度的香蕉汁、熟烂香蕉汁和纯水的选择。结果表明,犬蝠对纯成熟香蕉汁的选择性最强,取食次数和取食量均最高,而停留时间也最长;说明犬蝠具有分辨不同浓度的气味差异。我们推测犬蝠在野外觅食时可能优先取食成熟水果。     

生态公益林林果高效经营评价方法研究

以森林健康度、生物多样性、生物量、碳储量和经济产出值等构建生态公益林林果高效经营评价指标体系,提出以生态公益林林果高效经营综合指数(AI)衡量林果经营状况,并以此对广东省惠东县梁化林场林果实验地进行经营评价。结果表明,实验地AI指数为0.4288,林果实验地近两年的经营评价等级为中等。     

Compounds Interacting with the Ethylene Receptor in Plants

Abstract: Some of the compounds binding to the ethylene receptor induce an ethylene response, but others prevent it. The compounds preventing an ethylene response have been developed into a means for protecting plants against ethylene and extending the life of some plant material. 1-Methylcyclopropene (1-MCP), a compound now commercially available under the names EthylBloc and SmartFresh™, is currently being used on flowers, fruit and vegetables with great success. In ethylene sensitive flowers, among other responses, it prevents senescence and abscission of plant organs; in fruit and vegetables it slows down the ripening process. Other similar compounds are now being developed for a range of methods of application.     

Indirect evidence that frugivorous birds track fluctuating fruit resources among rainforest patches in the Northern Territory,Australia

Abstract Rainforests are naturally fragmented in the Northern Territory of Australia. A census of fruit and frugivorous bird abundance was taken monthly in 10 rainforest patches for 1 year and quarterly for a second year to investigate spatial and temporal patterns among the patches. Fruit abundance showed a marked annual cycle, with a peak around December in the wet season. Four of six bird species showed a significant seasonal fluctuation in abundance, and for three of them, these patterns were different among rainforest types. Three species also showed a significant tendency to be most abundant in the rainforest type with the most fruit in any month. We interpret these results as evidence that birds track fruit resources among rainforest patches of different types. The abundance of two of the species (figbird and pied imperial‐pigeon) was highly variable and did not reveal significantly different temporal trends among rainforest types. These species are probably even more mobile than the other species, although the data in the present study cannot be used to test this theory. The conservation of frugivorous birds and of the plants whose seeds they disperse will require the protection of networks of rainforest patches.     

Improved detection methods for fruit tree phytoplasmas

Phytoplasmas infecting fruit trees are considered quarantine organisms in Europe and North America. Detection often is hampered by their extremely irregular distribution in host plants. A sensitive, specific and quick diagnostic test would be highly desirable for routine detection, mainly to avoid using infected planting material. PCR methods require tedious preparation of DNA; also, the available primers are highly specific and exhibit some homology to chloroplast and plastid DNA. To address these problems, we compared several DNA preparation protocols for purity of DNA, cost and time required. We also developed new primers using rDNA sequence information from an Austrian isolate of European Stone Fruit Yellows (ESFY). These primers operate at high annealing temperatures and, thus, increase the specificity and decrease the risk of false positives. The primers could reliably detect the European phytoplasmas (AP, ESFY and PD) within a collection of isolates maintained in micropropagated periwinkle. Thus, they are suitable as general primers for phytoplasma detection. The primers also can be used for strain identification by direct PCR followed by RFLP analysis as demonstrated with micropropagated fruit tree material. Finally, an IC-PCR method that uses the primers for AP detection was found very sensitive and suitable for large-scale testing of apple materialin vivo andin vitro.     

Variation in nitrogen source utilisation by Pisolithus isolates maintained in axenic culture

The influence of various inorganic and organic nitrogen sources on biomass production by 17 isolates of Australian Pisolithus spp. was investigated before and after a 3-year maintenance period in axenic culture. While some isolates produced similar or higher amounts of biomass on NH₄ ⁺ or certain amino acids after the maintenance period, there was a general trend to reduced biomass production on these substrates. Biomass production by most isolates on bovine serum albumin increased significantly after maintenance. The data are discussed in relation to the use of axenic culture growth experiments for investigations of inter- and intraspecific physiological variation in ectomycorrhizal fungi. Accepted: 22 February 2001     

Cell division and cell enlargement in fruit of Lagenaria leucantha as influenced by pollination and plant growth substances

The effects of NAA (naphthaleneacetic acid), GA₃ (gibberellic acid), CPPU (N-(2-chloro-4-pyridyl)-N'-phenylurea) and pollination on fruit set, cell division and enlargement were studied in Lagenaria leucantha, an important vegetable. NAA and GA₃ were ineffective in inducing parthenocarpy, whereas CPPU induced parthenocarpic fruit significantly larger than fruit that resulted from pollination. Cell division, which occurred during the first 4 days after pollination was not reactivated by NAA or GA₃, but was effectively reactivated by CPPU. The cell number of the total cross-section of CPPU-treated fruit was 117.4% of that of pollinated fruit and 154.4% of that of unpollinated at 12 DAA (days after anthesis) respectively. The CPPU-induced parthenocarpic fruit had the largest cell cross-sectional area followed, successively, by pollinated fruit, NAA-treated fruit, GA₃-treated fruit and unpollinated fruit. These results indicate that CPPU induced parthenocarpic fruit growth by directly reactivating cell division and expansion.