On the Composition, Deposition and Mobilization of Proteins in the Cotyledons of Castor Bean (Ricinus communis L. cv. Hale) Seeds: Their Role as Storage Proteins

Proteins in the soluble and insoluble fractions, extracted frommature castor bean cv. Hale seed cotyledons, differ quantitativelyand qualitatively from their counterparts extracted from theendosperm. The soluble fraction contains no glycoproteins, andthe lectins RCA₁ and ricin D are absent. While the insolubleproteins are electrophoretically and immunologically similarto those in the endosperm, they do not form the 100 kD subunitdimers which characterize some of the endosperm insoluble crystalloidproteins. Rapid rates of deposition of all of the soluble andinsoluble proteins present in the mature seed cotyledons commences30–35 d after pollination (DAP) and continues until 45DAP. These proteins are mobilized rapidly beginning 1–2d after seed imbibition and this coincides with an increasein specific activity, in the cotyledons, of two aminopeptidasesand a carboxypeptidase. The soluble and insoluble proteins inthe cotyledons of the mature seed probably function as storageproteins and support the growth of the germinated seed priorto the mobilization of the major protein storage reserves ofthe endosperm. Key words: Ricinus communis, Castor bean, Hale cultivar, Cotyledon, Storage protein, Seed development, Seed germination     

Methods of studying the distribution, diversity and abundance of birds in East Africa—some quantitative approaches

In this paper we compare the use of transect counts with a simpler method of investigating bird diversity and numbers, particularly in terrestrial habitats, both natural and non‐natural. Transect Counts (TCs) have long been widely used, whereas Timed Species Counts (TSCs), which estimate relative abundance, are comparatively untried. We find that TSCs give results which are comparable to those from TCs in most respects, except that they can only be used indirectly for estimating population densities, and they give different measures of diversity. However, TSCs generate data on many more species much faster than do TCs and are therefore more cost‐effective in most situations. In particular, TSCs are useful for community studies. We show, for example, that in natural habitats bird populations are positively correlated with the amount of woody vegetation, but not with rainfall. Diversity too increases with woody vegetation. Because TSCs are simple, more of them can be made for a given input of time, and hence more distributional data are obtained as an additional benefit.     

Bemisia tabaci （Hemiptera： Aleyrodidae） nymphal feeding in cotton （Gossypium hirsutum） leaves

We used brightfield electron microscopy （BEM）, differential interference contrast microscopy （DICM）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and confocal laser scanning microscopy （CLSM） to investigate the stylet pathways of Bemisia tabaci during nymphal feeding behavior in cotton leaves beginning with penetration of the abaxial leaf surface and ending with stylets in sieve tubes in phloem tissues. Most nymphal stylets within salivary sheaths penetrating leaf tissues made complex turns and developed more than one salivary sheath branch before ending in sieve tubes. The external morphology of the salivary sheaths and their routes between and through leaf cells are described during the present study. Results showed the presence of the stylet within the sieve tubes. B. tabaci nymphs may remove stylets and feed in different sieve tubes. Ten short movies showing the progression of the stylet penetrations from adaxial surface to the sieve tubes are attached to Figures 8-15. The report and movies can be viewed from the internet. Download the movies to a local drive in your computer first for fast upload. The movies are posted on the website http：//www.ars.usda.gov/Services/docs.htm？docid=14629. The movies can be used as a teaching aid in biology classes.     

A NEW ARTHROPOD IN CHAIN-LIKE ASSOCIATIONS FROM THE CHENGJIANG LAGERSTÄTTE (LOWER CAMBRIAN), YUNNAN, CHINA

Abstract:  A new arthropod, Synophalos xynos gen. et sp. nov., is described from the Lower Cambrian of the Chengjiang Lagerstätte, Yunnan, China. It is provisionally assigned to Crustacea, Waptiida and Waptiidae. Just one example of an isolated individual of S .  xynos is known. Typically, individuals of the new species occur together in similar, robustly integrated chain-like associations. Such a strongly linked configuration is apparently unique for any arthropod, fossil or living. The chain-like association is suggested to represent an example of collective behaviour, possibly associated with reproduction, or more likely migration.     

Conservation and management of brown trout, Salmo trutta, in Scotland: an historical review and the future

SUMMARY. 1. Intensive research into the life history of brown trout started In 1948 when the Brown Trout Laboratory was opened in Pitlochry. Over the next 15 years significant contributions were made to the brown trout literature upon which the Laboratory based advice to landowners and anglers wanting to develop their fisheries. 2. Increasing pressure from the government for more work on Atlantic salmon tended to divert research funds and time away from brown trout investigations. The International Biological Programme's major study at Loch Leven from 1966 to 1972 ensured a continuing interest in trout in standing waters. Over this period little attention had been paid to trout in rivers. This changed when a number of investigations were started on the River Tweed by Edinburgh University. 3. A major constraint to brown trout conservation and management has been illegal fishing and lack of records on stocking activities and catches. The granting of Protection Orders under the Freshwater and Salmon Fisheries (Scotland) Act, 1976, has been a major incentive to increased interest in the improvement of trout fisheries. 4. Brown trout stocks have been reduced in certain areas due to the effects of afforestation, acidification, land drainage and farm wastes. Various remedial measures have been proposed and implemented. 5. To meet the increasing demands for trout fishing, many loch and reservoir fisheries are now stocked with rainbow trout in preference to brown trout. Attention should be paid to the interaction of these two species in both standing and in running waters., where fish farm escapees and inadvisable releases go unrecorded. 7. Research into the genetic effects on wild stocks from the liberation of large numbers of hatchery-reared brown trout has been lacking and probably many ‘pure’ indigenous stocks have been lost. More work in this field is essential. 8. Proposals are outlined for future brown trout research and recommendations are made for better management. Suggestions are also put forward for changes in the legislation to further protect Scottish brown trout stocks.     

Genetic assessment of species boundaries in the North American Daphnia longispina complex (Crustacea: Daphniidae)

Species boundaries in the North American Daphnia longispina group have proved difficult to establish on the basis of morphology alone. This confusion may be due to hydridization, phenotypic plasticity or the existence of sibling species. We therefore used genetic analysis to delineate species boundaries by examining 27 North American populations belonging to the longispina complex for variation at 15–26 allozyme loci. The populations consisted of Daphnia thorata from two western sites and two eastern sites, Daphnia galeata mendotae from its type location and seven sites across its range, and Daphnia rosea from eight temperate and seven arctic sites. Two populations from the Eurasian longispina complex were also included for reference. Populations assigned to D. galeata mendotae formed a genetically cohesive group, whereas a genetic dichotomy was found between temperate and arctic D. rosea , suggesting that this taxon includes two species. Genetic analysis also confirmed the distinctness of western D. thorata from other members of the longispina group. Unexpectedly, eastern populations resembling D. thorata were genetically more similar to temperate D. rosea than to any helmeted species ( D. galeata, Daphnia hyalina or D. thorata ). Our results suggest that the helmet character is a poor indicator of phylogenetic relationships, as the genetic ability to produce this feature has been lost or acquired several times in the evolution of the longispina group.