Ecological and Evolutionary Aspects of Integumentary Respiration: Body Size, Diffusion, and the Invertebrata

SYNOPSIS. Most animal phyla lack specialized respiratory surfacesand all phyla contain groups that, for some part of their lifehistory, depend entirely upon integumental diffusion of respiratorygases. Animals that are diffusion-limited, yet function aerobicallyare generally small with large surface areas and there has beenconvergence for this among all phyla including the coelomateinvertebrates. Acoelomates lack specialized respiratory structuresbut have highly modified integuments, functional specializations,and features ranging from symbioses to air gulping that compensatefor diffusion limitation. The diversity of structures functioningfor integumentary respiration is much greater among invertebratesthan vertebrates. Among the higher invertebrates with respiratorysurfaces, accessory integumentary O₂ uptake is usually 20 to50% of total respiration. The high diffusion constant of O₂in air minimizes boundary effects on gas transfer and permitslarger body size, although this is limited by dry conditions.Terrestrial annelids and flatworms, both confined to moist habitats,are larger than aquatic forms which often have accessory gills.Size differences between terrestrial forms in these two phylareflect the presence of a circulation in the annelids. Ontogenetictransitions from skin breathing to other respiratory structuresoccur among marine invertebrates and vertebrates. Vertebratesapparently exercise greater integratory control over integumentalrespiration through adjustment of ventilation and perfusion;however, it is not known if these processes occur in some invertebrates.     

Mycological studies on the equine intestinal tract with particular reference to equine dysautonomia (grass sickness)

A wide variety of non-endophytic fungi was isolated from the stomach, colon and rectum of healthy horses, horses suffering from equine dysautonomia and horses suffering from other disorders clinically resembling dysautonomia. Of the isolates with toxin-producing potential, species of Aspergillus and Penicillium predominated. Absidia spp. occurred in virtually all horses and Rhizopus was very common, but neither is known to produce toxins. The survey did not associate any particular fungal species with equine dysautonomia.     

A preparation of the stick insect Carausius morosus for recording intracellularly from identified neurones during walking

ABSTRACT. Using a preparation of the stick insect it is possible to record activity from the neuropile of the mesotheoracic ganglion during sequences of walking behaviour lasting several minutes. The animal walks on two lightweight wheels, counterbalanced to give an upthrust of 0.4 g against the legs. Each wheel may be rotated independently during turning behaviour. The walking behaviour of the operated preparation is compared with the results obtained for free-walking animals, and intact or partially operated preparations, walking on heavier wheels and mercury. Records from several identified retractor motor neurones show the stability and reproducibility obtainable with this preparation.     

MULTIVARIATE ANALYSIS OF CONVENTIONAL PROFILING DATA: A COMPARISON OF A BRITISH AND A NORWEGIAN TRAINED PANEL

Many studies have shown that conventional profiling provides reproducible and meaningful results. However, comparison of the technique as used in different countries appears to be nonexistent. In addition, data analysis is often approached differently, and this aspect is also addressed. This paper describes a study to compare the results obtained from profiling milk chocolate samples, using trained panels in Britain and Norway. Data were analyzed using principal component analysis, generalized Procrustes analysis and partial least squares regression. Results indicate that the underlying perceptual structure of the sample spaces obtained from both panels were similar, however, the emphasis on the underlying sensory dimensions differed. Moreover, it was possible to calibrate the two profiles, which has implications for marketing products for export, as well as providing a potential tool for panel monitoring and calibration across cultures.     

Variation among 41 Genotypes of Tomato (Lycopersicon esculentumMill.) for Crossability toL. peruvianum(L.) Mill.

Even with the aid of tissue culture, crosses betweenLycopersiconesculentum(E) andL. peruvianum(P) typically yield few progeny.To determine whether some E genotypes produce more progeny perfruit that others when crossed with P, 41 E genotypes were crossedwith pollen bulked from five P accessions. This first experiment(expt 1) was replicated over 2 years. In a second experiment(expt 2), differences among three genotypes each of E and P,and among individual plants within E genotypes were investigated.The E genotypes for expt 2 were chosen for relatively high andlow crossability based on results of expt 1. The P genotypesfor expt 2 were from different accessions than those used inexpt 1. For both experiments, the 15 largest ovules from eachripe fruit were cultured aseptically for 1 month. Out of 1228fruit, 753 hybrids were obtained. For expt 1, significant genotypeby year interactions were observed. Within each year, therewere significant differences among E genotypes for crossability.In expt 2, significant effects were found for E genotypes, butnot for interactions between E and P genotypes, P genotypes,nor plants within E genotypes. Moreover, general crossabilityfor E genotypes using bulked pollen (expt 1) was indicativeof general crossability with three P accessions not presentin the bulk (expt 2). Thus, selecting E genotypes of high crossabilityto P is the key to obtaining progeny for gene introgression.Rare production of ExP seed which was large and had brown seedcoats typical of E seed indicated strong selection pressureto maintain separate species, but gene exchange in nature maybe possible albeit at a low rate over long periods of time. Interspecific hybridization; Lycopersicon esculentum; Lycopersicon peruvianum; ovule culture; speciation     

Yearly variation in seasonal patterns of honeyeater abundance,flower density and nectar production in heathland near Sydney

Despite a consistent seasonal pattern of daily production of nectar-energy per unit area with peak production around the end of May, the seasonal pattern of honeyeater abundance is not consistent between years and does not correspond to the pattern of nectar-energy production.