THE OCCURRENCE OF COLI-AEROGENES ORGANISMS ON PLANTS

SUMMARY: Coli-aerogenes bacteria were seldom found on the foliage of a wide variety of garden plants, trees and shrubs, and field plants, including pasture, except where there was a possibility of contamination by insects, animals or dust. They were present in only a few instances on the flowering heads of hay plants (wind pollinated) but on almost all the flowers of garden plants (insect pollinated). Although cereal crops are wind pollinated, coli-aerogenes organisms were found on about one-third of the grains examined. The question of their origin on grain is discussed.
In a series of paired samples of soil and of the foliage of the covering vegetation, coli-aerogenes organisms were present in most of the soil samples, but were absent from the foliage except where animal contamination was possible, as in the case of grazed pasture.
With foliage samples unlikely to have been contaminated by animals, most of the coli-aerogenes organisms isolated were A. cloacae , but with grazed pasture E. coli predominated, indicating contamination by grazing animals.
The coli-aerogenes floras of garden flowers and cereal grains corresponded closely, consisting in each case largely of A. cloacae .     

Influence of fire severity on the regeneration,recruitment and distribution of eucalypts in the Cotter River Catchment,Australian Capital Territory

Abstract Plant responses to fire are variable between and within species and are influenced by numerous factors including fire severity. This study investigated the effects of fire severity on the regeneration and recruitment of forest eucalypts in the Cotter River Catchment, Australian Capital Territory (ACT). This study also examined the potential for the obligate seeder Eucalyptus delegatensis R.T. Baker (Myrtaceae) to expand into adjacent stands dominated by the facultative resprouter Eucalyptus fastigata H. Deane & Maiden (Myrtaceae) by seed shed and seedling establishment beyond the pre‐fire boundary. Sites were located in areas of either higher or lower fire severity, and transects were placed across the boundary of stands of E. delegatensis and E. fastigata. Species distributions, tree survival and seedling densities and heights were recorded, and the location of each boundary was determined as the region of maximum change in species composition along the transects. Eucalyptus delegatensis was the only eucalypt killed by higher severity fire. However, E. delegatensis seedling density was greater at higher severity sites than lower severity sites. Eucalyptus fastigata seedling density was low across all sites, with other eucalypts producing few, if any, seedlings. There was no evidence that E. delegatensis had increased its range into downslope stands dominated by E. fastigata. Patterns of vegetative recovery and seedling recruitment may be related to a number of factors, including differences in allocation patterns between seeders and sprouters, and the effects of overstory and understory competition. It is unclear what processes impede E. delegatensis seedling establishment beyond the stand boundary, but may involve an inability of E. delegatensis to shed seed sufficiently far downslope; unsuitable conditions for germination beyond the boundary; or, competition from a retained or resprouting overstory, despite the potential for increased dispersal distance soon after fire.     

Trophic level asynchrony in rates of phenological change for marine,freshwater and terrestrial environments

Recent changes in the seasonal timing (phenology) of familiar biological events have been one of the most conspicuous signs of climate change. However, the lack of a standardized approach to analysing change has hampered assessment of consistency in such changes among different taxa and trophic levels and across freshwater, terrestrial and marine environments. We present a standardized assessment of 25 532 rates of phenological change for 726 UK terrestrial, freshwater and marine taxa. The majority of spring and summer events have advanced, and more rapidly than previously documented. Such consistency is indicative of shared large scale drivers. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. Less coherent patterns in some groups of organisms point to the agency of more local scale processes and multiple drivers. For the first time we show a broad scale signal of differential phenological change among trophic levels; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services.     

Effect of the Nitrogen Supply on the Activities of Isoenzymes of NADH-dependent Glutamate Synthase and Glutamine Synthetase in Root Nodules of Phaseolus vulgaris L.

This paper has investigated the regulation of the activitiesof glutamine synthetase (GS) and NADH-dependent glutamate synthase(NADH-GOGAT) of Phaseolus vulgaris in relation to the nitrogensupply. The activity of NADH-GOGAT II, which is the most abundantisoenzyme of glutamate synthase in root nodules of P. vulgaris,was either absent or barely detectable in other organs of thisspecies. Moreover, its activity in roots could not be inducedby ammonium. In nodules NADH-GOGAT II activity was detectedin nodules grown under an atmosphere of 80% argon: 20% oxygenand in nodules formed with a Fix- Rhizobium mutant. However,in these non-fixing nodules the activity of this isoenzyme attainedless than 15% of the activity in fixing nodules and switchingargon/oxygen grown nodules to nitrogen/oxygen led to an increasein this isoenzyme within 24 h. This effect could not be mimickedby the addition of exogenous ammonium. Ammonium addition, however,promoted nodule senescence and also led to a decrease in theactivities of nitrogenase and plant GS. In particular, the nodule-enhancedGS isoenzyme but not the GSß isoenzyme was affectedby these changes and in a manner similar to the changes in NADH-GOGATII. The activity of the NADH-GOGAT I isoenzyme was detectablein other organs of P. vulgaris and in nodules its activity alsoshowed some changes in response to the rate of dinitrogen fixation. Key words: Glutamate synthase, glutamine synthetase, nitrogen fixation, nodule metabolism, Phaseolus vulgaris     

The MacVuti sampler: a new and inexpensive volume sampler for plankton and water

SUMMARY. Details are presented for the construction and operation of a cheap simple volume sampler for Zooplankton and water. This sampler has been used in waters up to 45 m deep over a number of years and proved to be reliable and effective.     

Opisthobranchiate Mollusca from Tanzania (Suborder:Doridacea)

Twenty-two species of Doridacea are described from the vicinity of Dar es Salaam, Tanzania. None is new to science, but one species of the genus Gymnodoris was too immature to be fully identified. Ten of the 22 species are known from the Hawaiian Islands, indicating that many species of dorid occur throughout the Indian Ocean and the Pacific as far as Hawaii. One species (Jorunna tomentosa) appears to be cosmopolitan, and two may possibly be confined to the coast of Africa (Chromodoris annulata and C. vicind).
Sixty-nine species of dorid have already been reported from Tanzania by Eliot. Nine species in the present collection were not found by him, so 78 are now known from the area.     

Microbiological Synthesis of Fat: THE FORMATION OF FAT FROM SUCROSE

1. Forty-three strains of moulds, selected from ten species,were examined to ascertain their capabilities as producers offat, when grown in four different solutions of nutrient inorganicsalts together with sucrose. The three highest yields of feltwere given by Penicillium javanicum van Beyma, P. Soppi Zaleski,and Aspergillus nidulans Eidam, in that order. The fat contenton felt weight was maximal at 34·8 per cent, with P.Soppi, at 28·4 per cent. with Fusarium lini(1), and at25·8 per cent. with A. nidulans; on sugar utilized itwas maximal at 11·4 per cent. with P. Soppi, at 7·9per cent, with A. nidulans, and at 5·6 per cent. withF. lini(1). 2. Other moulds considered worthy of further trial were P. spinulosum,P. aurantiobrunneum, F. graminearum, A. flavus, F. oxysporum,A. clavatus, and P. oxalicum.