Dispersion and the size composition of the aerial insect fauna

Abstract. 1. Beetles sampled in Louisiana at higher levels in the atmosphere were significantly smaller than those sampled at lower levels, which suggests that passive buoyancy is important in high altitude dispersal.
2. A model of long-range dispersal is suggested which combines both active flight and passive buoyancy.     

Suppression of the Tumorous State in Crown Gall Teratomas of Tobacco A Clonal Analysis

Two types of experimental approaches designed to test the possible involvement of chimeras in the persistent but readily reversible suppression of the tumorous state and in a recovery from that state in crown gall teratomas of tobacco were investigated. These studies showed that the tumorous state was suppressed in specialized cells present in the different tissues derived from each of the three layers of the apical meristem of teratoma-derived shoots of clonal origin. Although differences existed in the exogenous requirements needed for the reestablishment of the tumorous state in the different specialized cell types present in the different tissues, all again acquired a capacity for autonomous growth when appropriately stimulated. No evidence was found for the existence of periclinal or sectoral chimeras in teratoma-derived shoots of a single cell origin. Chimerism was, however, found to exist in one noncloned teratoma-derived shoot. Analysis of more than 500 clones derived from leaf mesophyll cells of cloned teratoma shoots showed that the vast majority of them (> 99%) were tumorous, while all of the 144 seed-grown plants from these shoots had completely recovered from the tumorous state. The results of these studies suggest that (a) a teratoma shoot does not depend for its development on the presence of significant numbers, if any, of cells that had recovered from the tumorous state; (b) the tumorous state may be suppressed in even the most highly specialized cells; (c) some special mechanism exists in the meiotic process for the elimination of all or most of the foreign DNA from transformed cells.     

SENSORY AND INSTRUMENTAL FLAVOR ANALYSES OF CHEESE CURD COCULTURED WITH SELECTED YEAST AND BACTERIA

Relationships between odor properties and volatile chemical composition were explored on 39 cocultures of three different yeasts, three Geotrichum candidum and five bacteria, commonly used in bacteria and mold surface ripened cheese. Sensory profiling was performed by ten trained judges by scoring the intensity of 14 odor attributes. At the same time, the volatile compounds of the cocultures were extracted and analyzed by dynamic headspace gas chromatography and mass spectrometry. Sensory and instrumental data were compared and correlated using correlation analysis and partial least squares regression analysis. The sample plot including the whole set of samples evidenced a clustering of the associations containing the yeast strain Kluyveromyces lactis and any bacteria. They developed strong fruity olfactory notes related to their high content of ethyl esters and various alcohols. The sample plot on a restricted set of samples evidenced the fruity characteristics of Debaryomyces hansenii and bacteria associations and the cheesy odors of Yarrowia lipolytica and Geotrichum candidum cocultures that produced sulfur compounds.     

Methods for the Large-Scale Cultivation of an Oxytricha (Ciliophora: Hypotrichida)1

ABSTRACT. Oxytricha strains used in biochemical studies have traditionally been grown in unaerated, unagitated culture tubes or Fernbach flasks. These cultures are limited in volume to about one liter and have a very nonuniform distribution of cells, with the majority of the cells at the very top or bottom of the medium. We have found conditions in which Oxytricha can be grown in 50-liter fermentation vats. The cultures grow to a uniform density of about 6000 cells/ml.     

Partitioning of sugars in Lolium perenne (perennial ryegrass) during drought and on rewatering

Simulated swards of perennial ryegrass ( Lolium perenne ) growing in 1-m³ soil blocks in the glasshouse were either well watered or deprived of water for 57 d and then rewatered. The first aim was to measure effects of drought on sugar (water-soluble carbohydrate) composition of laminae and sheaths of mature laminae, and bases and laminae of young (growing) leaves. The second aim was to use pulse labelling with ¹⁴CO₂ to follow the partitioning of recently-fixed assimilates, and the assembly and consumption of reserve sugars (fructans). Over the last 7 d of drought growth almost stopped, old leaves died faster than they were replaced, and total sugar (which had doubled in concentration during drought) was rapidly consumed. Leaf laminae had lower content of total sugars and of large fructan (DP>5) than did growing bases and sheaths. Drought greatly reduced the rate at which sugar was exported from the laminae to the sheaths and growing leaf bases, and the rate at which it was converted to fructan. Nevertheless, fructan accumulated over the first 50 d of drought. Rewatering did not result in depolymerization and remobilization of sugars that had been formed during the last 7 d of drought, but stimulated their further assembly into high-DP fructans. Our hypothesis, that accumulation of neo-kestose (a DP-3 fructan) in droughted laminae was a symptom of sugar remobilization just before death, was disproved. It is concluded that sugar reserves contribute to drought resistance only under extreme conditions. The specific role of fructan in dry environments might be to improve regrowth when drought is relieved, rather than to enhance growth during drought.