Recombinant and wild-type Pseudomonas aureofaciens strains introduced into soil microcosms: effect on decomposition of cellulose and straw

The effect of a genetically engineered Pseudomonas aureofaciens (Ps3732RNL11) strain (GEM) and the parental wild-type (Ps3732RN) on decomposition of cellulose paper, straw and calico cloth was assessed after 18 weeks incubation in laboratory soil microcosms. Effect(s) of inoculum density (10³, 10⁵, and 10⁸ cells/ g dry soil) and single versus multiple bacterial inoculations were also investigated. Cellulose paper was completely decomposed after 18 weeks in all treatments. There were no significant differences (95% level), between treatments, in percentage decomposition of either straw or calico cloth. Recovery of the GEM at 18 weeks, using viable plating, was limited to treatments originally receiving 10⁸ cells/g dry soil. Log 1.8 CFU/g dry soil were recovered from the single dose treatment while log 4.2 CFU/g dry soil were recovered from the multiple dose treatment Biolog metabolic tests were used to determine if the GEM or parental wild-type had any effect on overall carbon utilization in soil. Results suggested they did not. Detection of the recombinant lacZY gene sequence in soil using PCR suggested the possibility of viable but nonculturable cells and/or persistence of chromosomal DNA.     

Symbiosis in the Larger Foraminiferan Sorites marginalis (with Notes on Archaias spp.)

SYNOPSIS. It was demonstrated with the aid of light and electron microscope studies that Sorites marginalis (Lamarck) harbors zooxanthellae. The hosts were scraped from Thalassia testudinum Konig growing in Key Largo Sound (Florida, U.S.A.) and immediately preserved in appropriate fixatives. Zooxanthellae were distributed unevenly throughout all the chamberlets; only a few symbiotes were found in the embryonic chambers and the inner or outer chambers, but the intermediate chambers were packed with symbiotes. The outer chambers contained many food vacuoles in addition to symbiotes. Some zooxanthellae might have been in the process of degeneration or digestion. The symbiotes were found to have a typical dinoflagellate nucleus, a single large lobate cortical chloroplast with one stalked pyrenoid, an accumulation body, and many starch granules. The nonmotile stage of the zooxanthella was similar, but perhaps not identical, to Symbiodinium microadriaticum Freudenthal from various hosts.
The foraminiferan host is heterokaryotic with hundreds of generative (small) nuclei and scores of vegetative (large) nuclei. Most of the generative nuclei were found in the embryonic apparatus and the inner chambers. Most of the vegetative nuclei were found in the inner and outer chambers.     

在广东对按蚊出入居室与室内栖息情况的观察

按蚊生态学是研究消灭按蚊的基础,也是疟疾流行病学调研的组成部分。不可设想在按蚊生态知识缺乏的情形下,能制定有效合理的灭蚊措施和对流行病学调查能提供正确的依据。 自1956年起,几年来我们在广东省从化县进行了一系列按蚊生态调查研究工作;其中,关于按蚊飞出室外活动和室内的栖息问题,曾引起我们很大的兴趣和注意,这里首先     

Experimental studies of foraging in complex laboratory environments

The value of examining hummingbird foraging behavior in complexlaboratory environments is discussed relative to decision theoryand experimental components analysis, and an experimental systemis described. The system provides control of metabolic, behavioral,and environmental variables, and allows automatic recordingand efficient analysis of behavior. Specific research applicationsof the system are discussed, including studies of adjustmentof food intake to changes in food concentration, discriminationand choice among food sources, and spatial memory organization.     

Algal Flagellate Symbiosis in the Foraminifer Archaias*†

SYNOPSIS. A symbiotic alga from the foraminifer Archaias angulatus was isolated axenically. Algae from crushed hosts were coccoid and highly vacuolated; division stages within an envelope were common. Biflagellate motile piriform organisms predominated in newly transferred cultures and were gradually replaced by the coccoid, highly vacuolated stage. Incorporation of ¹⁴C label in intact Archaias was greatest for organisms fed and incubated in light. Starved symbiotized organisms incubated in the light incorporated ～30% as much label as fed counterparts, There was no obvious difference in ⁴⁵Ca incorporation between fed and starved organisms. Light significantly enhanced calcification. The Archaias symbiont infected Rosalina leei but not Quinqueloculina spp.     

Nucleotide Diversity of the Colorless Green Alga Polytomella parva (Chlorophyceae,Chlorophyta): High for the Mitochondrial Telomeres,Surprisingly Low Everywhere Else*

ABSTRACT. Silent‐site nucleotide diversity data (π_silent) can provide insights into the forces driving genome evolution. Here we present π_silent statistics for the mitochondrial and nuclear DNAs of Polytomella parva, a nonphotosynthetic green alga with a highly reduced, linear fragmented mitochondrial genome. We show that this species harbors very little genetic diversity, with the exception of the mitochondrial telomeres, which have an excess of polymorphic sites. These data are compared with previously published π_silent values from the mitochondrial and nuclear genomes of the model species Chlamydomonas reinhardtii and Volvox carteri, which are close relatives of P. parva, and are used to understand the modes and tempos of genome evolution within green algae.     

Minimal Defined Media for Vegetative Growth of the Acrasian Polysphondylium pallidum WS-320*

SYNOPSIS. Polysphondylium pallidum WS-320 grows indefinitely as vegetative amebae in a liquid medium where (a) substrates comprise sucrose, glycerol, acetate, lactate, citrate, and glutamate; (b) essential nutrients (riboflavin, lysine, glycine, and possibly several other amino acids that may be essential) are supplied. The growth thus supported (2 × 10⁶ cells/ml) is more than doubled by provision of a mixture of crude fatty acids, an acid hydrolysate of casein supplemented with B vitamins, purines, pyrimidines, and fat-soluble antioxidants.     

The effects of quantity and duration of simulated pollutant nitrogen deposition on root-surface phosphatase activities in calcareous and acid grasslands: a bioassay approach

A field and laboratory based bioassay has been developed to investigate the effects of the quantity and duration of simulated pollutant nitrogen (N) deposition on root-surface phosphomonoesterase (PME) activities in calcareous and acid grasslands. Seedlings of Plantago lanceolata were transplanted to a calcareous grassland and Agrostis capillaris seedlings were grown in microcosms containing soil from an acid grassland that had received either 7 yr (long-term) N additions or 18 months (short-term) N and phosphorus (P) additions. The bioassay revealed that short-term N treatments had little effect on the enzyme activity, whereas long-term N additions significantly increased PME activity within 7 d of transplanting into the field plots. Root-surface PME activity of A. capillaris was significantly reduced in soil that received additions of P. In the plots receiving long-term additions of N, a strong relationship was observed between extractable soil ammonium and root-surface PME activity. Soil ammonium concentrations accounted for 67% of the variation in PME activity of P. lanceolata in the calcareous grassland, and 86% of the variation in PME activity of A. capillaris in the acid grassland. These results provide evidence that N deposition may have considerable effects on the demand and turnover of P in ecosystems that are approaching or have reached N saturation.