Biology and Structure of Phytomonas staheli sp. n., a Trypanosomatid Located in Sieve Tubes of Coconut and Oil Palms

SYNOPSIS. Phytomonas staheli sp. n. is described from the oil palm ( Elaeis guineensis ) and the coconut palm ( Cocos nucifera ) of Surinam, South America. The phytomonad is the probable cause of "Hartrot" in the coconut palm and "Marchitez sopresiva" in oil palms. Parasites are confined to the sieve tubes in palms. Some success was obtained at cultivation of the organism from Elaeis.     

The Search for a Jural Rule: Women in Southeast Asia—the Northern Thai Cults in Perspective

… female ties dominate in the area of descent, residence and inheritance… in northern Thailand there is an ideology of male dominance but a social structural dominance of females. Perhaps in other peasant societies of Southeast Asia, as well, the celebrated ‘equality of the sexes’ thought to be typical of the region might best be considered in these terms. (Davis 1974:79)     

Genomic hybridization of bovine class II major histocompatibility genes: 2. Polymorphism of DR genes and linkage disequilibrium in the DQ-DR region

Summary. Class II genes of the bovine major histocompatibility complex have been investigated by Southern blot analysis using human cDNA probes for DQα, DQβ, DRα and DRβ. In this report restriction fragment length polymorphisms of DR α and DR β are described. The polymorphisms were interpreted genetically by analysing five paternal half-sib families of the Swedish Red and White Breed, comprising altogether 28 offspring. Using the restriction enzymes Bam HI, Eco RI and Pvu II, three DRα and three DRβ allelic fragment patterns were resolved. The DR α and DR β genes thus appear to be much less polymorphic than the previously described DQ α and DQ β genes. Also, the observed linkage disequilibrium between DR genes was less pronounced than that between DQ genes, whereas the association between DR and DQ haplotypes was very strong. The family data available indicated strongly that the DQ α, DQ β, DR α and DR β genes are all closely linked.     

Anatomy of hydathodes and pigment disks in leaves of Ficus diversifolia (Moraceae)

In Ficus diversifolia , "mistletoe fig", hydathodes are scattered over the leaf lamina. They open to the adaxial surface via a circular, slightly depressed epidermal pad studded with 20–30 water pores. The epithem is a cylinder of small cells, irregular in shape, with conspicuous intercellular spaces, bounded by a close-fitting sheath of unpigmented cells. Hydathodes occur above characteristic junctions of three or more minor veins, from which short tracheary strands extend upward into the epithem and end blindly. Phloem does not seem to be involved. Unsuccessful attempts were made to induce guttation. Red pigment spots occur abaxially in the axils of major veins. They are compact internal disks of parenchyma cells containing granules of various sizes. A vascular bundle arches downward, passes over the disk, then curves upward to rejoin other bundles. The central large disk has a palisade epidermis of slender elongate cells separated from each other by cuticle; the other disks have a normal epidermis.     

Deterrence coding by a larval Manduca chemosensory neurone mediating rejection of a non-host plant, Canna generalis L.

Abstract. The physiological basis of phagodeterrence was studied electrophy-siologically and behaviourally in the phytophagous caterpillars Manduca sexta and Manduca quinquemaculata. The model unacceptable non-host plant was the canna lily, Canna generalis. A strongly deterrent extract was obtained from fresh leaves of canna by extraction with hot ethanol or ethyl acetate in a blender. Behavioural rejection of these extracts was similar to that of fresh leaves, although less intense. In contrast, blender extracts using other solvents, as well as leaf surface rinses, were phagostimulant or neutral. Chromatographic fractionation of the deterrent ethanolic extract showed the active principles to be moderately polar and separable into two fractions. Previous ablation experiments had shown that the medial maxillary styloconica and epipharyngeal sensilla are the two most important chemosensory organs in mediating behavioural rejection of canna leaves; if only one of these organs is spared, the animal completely rejects canna. We investigated the neural responses of the medial styloconica and their contribution to the sensory coding responsible for this phagodeterrence. The active fractions of the deterrent ethanolic extract elicited a vigorous response from one chemosensory neurone in the medial styloconica. This neurone is distinguishable from others in the medial styloconica by its unique temporal response parameters and the characteristic shape changes of its action potentials. The response frequency of this neurone correlates with the degree of phagodeterrence in a dose-dependent manner. Threshold deterrence occurs at a concentration of extract (1%) that elicits firing in this neurone at a rate of c. 50 spikes/s peak instantaneous frequency and 30 total spikes in the first Is. We conclude that this is a ’deterrent neurone’ in the sense that vigorous response from this neurone is a sufficient sensory code for behavioural rejection of canna. Thus input from a single sensory neurone is capable of blocking feeding, since only one (unilateral) medial styloconicum is needed to mediate this rejection.     

AUTHORIZING PSYCHIATRIC RESEARCH: PRINCIPLES,PRACTICES AND PROBLEMS

Psychiatric research is advancing rapidly, with studies revealing new investigative tools and technologies that are aimed at improving the treatment and care of patients with psychiatric disorders. However, the ethical framework in which such research is conducted is not as well developed as we might expect. In this paper we argue that more thought needs to be given to the principles that underpin research in psychiatry and to the problems associated with putting those principles into practice. In particular, we comment on some of the difficulties posed by the twin imperatives of ensuring that we respect the autonomy and interests of the research subject and, at the same time, enable potentially beneficial psychiatric research to flourish. We do not purport to offer a blueprint for the future; we do, however, seek to advance the debate by identifying some of the key questions to which better answers are required.