SEX-RATIO BIAS WITH ASYMMETRIC EXCHANGE OF POLLEN BETWEEN DEMES

In a patch of hermaphroditic plants, with a low level of pollen migration between patches, a prevailing wind creates a gradient, within the patch, in the strength of local competition among pollen for reproductive success. This leads to a sex ratio gradient, with a male (pollen) bias in downwind individuals, which can be quite strong even for large patches. The effect can be understood as follows: downwind individuals have relatively low reproductive value and respond by putting more resources into the gamete (pollen) with the best long-range (extra-patch) reproductive success.     

Yaba virus-specific DNA in the host cell nucleus.

DNA-DNA hybridization studies show that Yaba virus-specific DNA is present in the host cell nucleus late in the infection cycle. The nuclear DNA appears to exist as a complete genome, not convalently linked to host cell DNA, as demonstrated by sedimentation analyses. The DNA apperas to be synthesized in the nucleus, since its level of incorporation of label is ten times the background incorporation detectable in the cytoplasm. Extraction of the nuclei by treatment with SDS and EDTA after precipitation with 1 M NaCl separates most of cellular DNA from the Yaba virus-specific DNA.     

Molecular changes associated with tuberisation in Solanum tuberosum. Differential expression of α-tubulin isotypes

Changes in gene expression that occur in the stolon tips of potato ( Solanum tuberosum L.) cv. Record during tuberisation were investigated. Protein extracts from stolon tips at various stages in the tuberisation process were analysed by two-dimensional gel electrophoresis. A number of quantitative and qualitative changes in polypeptide composition accompanied the very early stages of tuberisation. In vitro translation of RNA extracted from stolon tips also revealed quantitative and qualitative changes associated with tuberisation. Immunoblotting of protein extracts with monoclonal antibodies raised against α- and β-tubulin showed quantitative changes in the relative level of β-tubulin, but not α-tubulin, as the stolon tips tuberised. Changes in the pattern of α-tubulin isotype expression were shown to occur at early stages in the tuberisation process.     

Automated quantification of sympathetic beat-by-beat activity, independent of signal quality.

Sympathetic nerve activity (SNA) can provide critical information on cardiovascular regulation; however, in a typical laboratory setting, adequate recordings require assiduous effort, and otherwise high-quality recordings may be clouded by frequent baseline shifts, noise spikes, and muscle twitches. Visually analyzing this type of signal can be a tedious and subjective evaluation, whereas objective analysis through signal averaging is impossible. We propose a new automated technique to identify bursts through objective detection criteria, eliminating artifacts and preserving a beat-by-beat SNA signal for a variety of subsequent analyses. The technique was evaluated during both steady-state conditions (17 subjects) and dynamic changes with rapid vasoactive drug infusion (14 recordings from 5 subjects) on SNA signals of widely varied quality. Automated measures of SNA were highly correlated to visual measures of steady-state activity (r = 0.903, P < 0.001), dynamic relation measures (r = 0.987, P < 0.001), and measures of burst-by-burst variability (r = 0.929, P < 0.001). This automated sympathetic neurogram analysis provides a viable alternative to tedious and subjective visual analyses while maximizing the usability of noisy nerve tracings.     

FOSSIL FUNGI (ENDOGONACEAE) FROM THE TRIASSIC OF ANTARCTICA

Fungal sporocarps are described from Triassic silicified peat deposits from Antarctica. Sporocarps possess a two-layered wall and contain a single spore. The outer layer is mycelial; the inner layer, noncellular. The combination of primitive and advanced features suggests that this fungus is intermediate in complexity between the lower and evolutionarily more advanced fungi. The Antarctic fungus and morphologically similar fossils resemble extant members of the Endogonaceae, but appear to have been saprophytes rather than mycorrhizal symbionts.     

The use of clip cages to restrain insects reduces leaf expansion systemically in Rumex obtusifolius

Abstract. 1. Clip cages have been used widely by experimental ecologists to contain insects on plants.
2. Under controlled conditions, the effect of applying clip cages alone and clip cages and the chrysomelid beetle Gastrophysa viridula on systemic leaf expansion of Rumex obtusifolius was investigated. Treatments were applied to the fully expanded fourth leaf and expansion of leaf 8 was measured over a period of 22 days.
3. The application of clip cages reduced the rate at which leaf area increased and led to reductions in final leaf areas.
4. Clip cages have systemic effects on plant development and these effects are sustained even after the clip cage is removed. Investigators should take this into account in designing experiments.