METHODS OF ASSESSING THE SPORICIDAL EFFICIENCY OF AN ULTRA-HIGH-TEMPERATURE MILK STERILIZING PLANT I. EXPERIMENTS WITH SUSPENSIONS OF SPORES IN WATER

SUMMARY: A method of assessing the sporicidal efficiency of a UHT milk sterilizing plant operating on water is described. Water heavily contaminated with spores of a strain of Bacillus subtilis was filtered, after treatment in the plant, through membrane filters and the surviving spores estimated by incubation of the membranes in nutrient agar. With this plant a temperature of c . 135° caused a 99·99999% kill of B. subtilis spores. Confirmation of the lethal effects of temperatures above 135° was obtained by passing treated water into 10 gal churns containing sterile concentrated nutrient broth and incubating the churns.     

The Response of the C3-CAM Tree, Clusia rosea, to Light and Water Stress: I. GAS EXCHANGE CHARACTERISTICS

Gas exchange measurements were undertaken on 2-year-old plantsof Clusia rosea. The plants were shown to have the ability toswitch from C₃-photosynthesis to CAM and vice versa regardlessof leaf age and, under some conditions, CO₂ was taken up continuously,throughout the day and night. The light response was saturatedby 120 µmol m^–2 s^–1 typical of a shade plant. Gas exchange patterns in response to light, water and VPD wereexamined. All combinations of daytime and night-time CO₂ uptakewere observed, with rates of CO₂ uptake ranging from 2 to 11µmol m^–2 s^–1 depending upon water status andlight. Categorization of this plant asC₃, CAM or an intermediateis impossible. Differing VPD affected the magnitude of changesfrom CAM to C₃-photosynthesis (0 to 0.5 and 0 to 6.0 µmolm^–2 s^–1 CO₂, respectively) when plants were watered.Under well-watered conditions, but not under water stress, highPPFD elicited changes from CAM to C₃ gas exchange. This is unusualnot only for a shade plant but also for a plant with CAM. Itis of ecological importance for C. rosea, which may spend theearly years of its life as an epiphyte or in the forest understorey,to be able to maximize photosynthesis with minimal water loss. Key words: Clusia rosea, CAM, C₃, stress     

The influence of biotope availability on macroinvertebrate assemblages in South African rivers: implications for aquatic bioassessment

1. Macroinvertebrate biotope preferences and the influence of differences in the availability of biotopes on individual taxa, macroinvertebrate assemblages and a biotic index, the South African Scoring System (SASS), were investigated in two regions of South Africa. 2. Among biotope differences in individual taxa and macroinvertebrate assemblages resulted in differences in SASS scores, with differences in assemblages being greater among biotopes than between sites. 3. All three metrics studied (SASS score, number of taxa and average score per taxon, ASPT), differed significantly among biotopes, with highest scores consistently recorded in the stones biotope, while lowest SASS scores and fewest taxa were recorded in the sand biotope. 4. SASS score and number of taxa were positively, while ASPT was negatively correlated with number of biotopes sampled. 5. The observed biotope differences highlight the importance of sampling and comparing data from sites separately for each biotope.     

Proportions of eggs laid by Aedes aegypti on different substrates within an ovitrap in Trinidad, West Indies

Abstract. Ovitraps were exposed outdoors during wet and dry seasons in Trinidad to determine the proportions of eggs laid on three substrates: the widely-used hardboard 'paddle' (P), the water surface (W) and the inside surface of the ovitrap wall (S) in three types of blackened ovitrap: round, glass (RG), round, plastic (RP) and rectangular, plastic (SP). Of the 3556 eggs obtained, most (86.4%) were laid during the wet season when statistically significant differences were detected between substrates but not between ovitrap types. Most eggs (>80%) were laid on P, significantly fewer ( P < 0.005) on W, on S and on W + S, thus confirming the superiority of the paddle as a device for monitoring oviposition activity. Implications of these findings for the interpretation of Aedes studies using ovitraps are discussed.     

The Effects of Actinomycin D,Gibberellin A7, and Cyclic AMP on Mating of Chlamydomonas reinhardtii*

SYNOPSIS. Gibberellin A7 and cyclic AMP increased mating efficiency of Chlamydomonas reinhardtii when the cells were treated during gametogenesis. No change in mating activity was observed when cells were treated with 5′-AMP. Actinomycin D inhibited both normal mating and gibberellin-stimulated mating.     

Isolation and characterization of 102 new microsatellite loci in Murray cod,Maccullochella peelii peelii (Percichthyidae), and assessment of cross‐amplification in 13 Australian native and six introduced freshwater species

We have isolated 102 polymorphic microsatellite loci from an enriched Murray cod DNA library and also assessed their amplification success in 13 native and six introduced freshwater fish species. The loci will serve the dual purpose of assessing wild population genetic structure for future conservation efforts, and for identifying markers for key quantitative trait loci important for aquaculture.