An ecological example of the application of projection pursuit to compositional data

A modern statistical technique for the exploratory analysis of multivariate data, called projection pursuit, is described. The method consists of the extraction and display of informative one- or two-dimensional projections of the multivariate dataset. Projection pursuit has much scope for application to ecological datasets. The example in this paper concerns element concentrations in soil samples from a coastal embayment on the east coast of Australia. The application attempts to search for patterns in the soils which could be related to vegetation patterns. The compositional nature of the dataset adds a novel element to the methodology.     

Human lymphocyte subpopulations: the effect of pregnancy.

Peripheral blood lymphocytes from pregnant and nonpregnant females were studied for the presence of the following surface receptors: (i) Receptor for heat-aggregated human IgG (AggIgG); (ii) Receptor(s) for complement components; (iii) Receptor for sheep red blood cells (SRBC). Absolute numbers of lymphocytes with receptors for complement and those with receptors for SRBC were present in equal numbers in both groups. However, in the pregnant females there was a significantly lower number of lymphocytes with receptors for AggIgG. It is hypothesized that some of the immunological changes which occur during pregnancy may be mediated partly through changes in the total numbers of certain lymphocyte subpopulations.     

FACTORS INFLUENCING BRAIN AND TISSUE LEVELS OF TRYPTAMINE: SPECIES, DRUGS AND LESIONS

With a modification of the spectrophotofluorometric (SPF) method of HESS & UDENFRIEND (1959) (J. Pharmac. exp. Ther. 127 , 175-177), brain tryptamine levels in the rat (20.9 ng/g) and guinea-pig (20.7 ng/g) were found to be less than those in the dog (32.1 ng/g) and cat (52.2 ng/g). Regional distribution studies in the dog and cat showed that tryptamine was present in all major brain regions with highest concentrations in the spinal cord. Blood levels of tryptamine in the guinea-pig, dog and cat (6-7 ng/ml) were lower than brain levels. Pargyline significantly increased brain tryptamine in both the dog and cat; whereas, isocarboxazid (after 4 h) increased brain tryptamine levels in the dog but decreased brain levels in the cat. Reserpine (0.5-1.0 mg/kg per day for 1-4 days) did not significantly decrease brain, spinal cord or blood tryptamine levels in the dog. Spinal cord transection did not decrease tryptamine levels below the lesion in the chronic spinal dog.     

The impacts of cytoplasmic incompatibility factor (cifA and cifB) genetic variation on phenotypes

Wolbachia are maternally transmitted, intracellular bacteria that can often selfishly spread through arthropod populations via cytoplasmic incompatibility (CI). CI manifests as embryonic death when males expressing prophage WO genes cifA and cifB mate with uninfected females or females harboring an incompatible Wolbachia strain. Females with a compatible cifA-expressing strain rescue CI. Thus, cif-mediated CI confers a relative fitness advantage to females transmitting Wolbachia. However, whether cif sequence variation underpins incompatibilities between Wolbachia strains and variation in CI penetrance remains unknown. Here, we engineer Drosophila melanogaster to transgenically express cognate and non-cognate cif homologs and assess their CI and rescue capability. Cognate expression revealed that cifA;B native to D. melanogaster causes strong CI, and cognate cifA;B homologs from two other Drosophila-associated Wolbachia cause weak transgenic CI, including the first demonstration of phylogenetic type 2 cifA;B CI. Intriguingly, non-cognate expression of cifA and cifB alleles from different strains revealed that cifA homologs generally contribute to strong transgenic CI and interchangeable rescue despite their evolutionary divergence, and cifB genetic divergence contributes to weak or no transgenic CI. Finally, we find that a type 1 cifA can rescue CI caused by a genetically divergent type 2 cifA;B in a manner consistent with unidirectional incompatibility. By genetically dissecting individual CI functions for type 1 and 2 cifA and cifB, this work illuminates new relationships between cif genotype and CI phenotype. We discuss the relevance of these findings to CI’s genetic basis, phenotypic variation patterns, and mechanism.     

Metabolic co-operation between biochemically variant hamster cells and heterokaryons formed between these cells and chick erythrocytes.

Observations on heterokaryons formed between multiple biochemically variant polyoma virus transformed hamster cells and chick erythrocytes indicate that gain of active preformed adenosine phosphoribosyl transferase and hypoxanthine/guanine phosphoribosyl transferase immediately endows the heterokaryons with the potential to act as donors for metabolic cooperation in these systems.     

The selection of somatic cell hybrids between human lymphoma cell lines.

Somatic cell hybrids have been selected between three pairs of established human lymphoid cell lines producing pure lines of proliferating hybrid cells: Raji/Namalwa, Raji/Daudi, and Raji/BJAB. The hybrid cell lines have been characterized with respect to isozyme pattern, volume, and karyotype.     

Phosphatidylglycerol-deficient lung surfactant has normal properties

We have investigated the effects of substituting phosphatidylinositol (PI) for phosphatidylglycerol (PG) on the functional properties of rabbit lung surfactant. We gave oral 10% glucose solution for 3 days to 11 rabbits and 10% inositol to 12 others. Lung lavage surfactant phospholipids were normal in both groups, except that PG was low and PI was high in the inositol group. Fatty acyl group distributions did not differ, except for a slight decrease of oleic acid in the inositol group. Electron microscopic examination showed normal surfactant structure in both. The time course of surfactant adsorption to an air-water interface was similar in both groups. Minimum surface tension after film compression was 4.0 +/- 0.8 mN . m-1 in the glucose group and 2.9 +/- 1.3 mN . m-1 in the inositol group (mean +/- SE). Surface potential-surface pressure isotherms were identical to within 12 mV. Arterial blood gases breathing air and 100% O2 were the same in both groups, as were pressure-volume curves of excised lungs, with both air and saline filling. The results suggest that, if acidic phospholipids are necessary for maintaining normal surfactant structure and surface properties, normal pressure-volume relationships, and normal gas exchange, then PI may substitute for PG.     

Synchronous biological feedbacks in parrotfishes associated with pantropical coral bleaching

Biological feedbacks generated through patterns of disturbance are vital for sustaining ecosystem states. Recent ocean warming and thermal anomalies have caused pantropical episodes of coral bleaching, which has led to widespread coral mortality and a range of subsequent effects on coral reef communities. Although the response of many reef‐associated fishes to major disturbance events on coral reefs is negative (e.g., reduced abundance and condition), parrotfishes show strong feedbacks after disturbance to living reef structure manifesting as increases in abundance. However, the mechanisms underlying this response are poorly understood. Using biochronological reconstructions of annual otolith (ear stone) growth from two ocean basins, we tested whether parrotfish growth was enhanced following bleaching‐related coral mortality, thus providing an organismal mechanism for demographic changes in populations. Both major feeding guilds of parrotfishes (scrapers and excavators) exhibited enhanced growth of individuals after bleaching that was decoupled from expected thermal performance, a pattern that was not evident in other reef fish taxa from the same environment. These results provide evidence for a more nuanced ecological feedback system—one where disturbance plays a key role in mediating parrotfish–benthos interactions. By influencing the biology of assemblages, disturbance can thereby stimulate change in parrotfish grazing intensity and ultimately reef geomorphology over time. This feedback cycle operated historically at within‐reef scales; however, our results demonstrate that the scale, magnitude, and severity of recent thermal events are entraining the biological responses of disparate communities to respond in synchrony. This may fundamentally alter feedbacks in the relationships between parrotfishes and reef systems.