The distribution of asynchronous muscle in insects with particular reference to the Hemiptera: an electron microscope study

Certain ultrastructural features of insect flight muscle are described and their value as criteria for differentiating between synchronous and asynchronous muscle is assessed. The distribution of asynchronous muscle in the Pterygota as a whole and the Hemiptera in particular is investigated and the evolutionary implications of the results are discussed.     

Immunosuppressive Effect of the Infectious Bursal Agent in the Chicken

IT is well established that in the chicken humoral antibody formation depends on the bursa of Fabricius, whereas delayed hypersensitivity and other manifestations of cellular immunity depend on the thymus for their development^1,2. Surgical bursectomy^3,4 and the administration of testosterone^5–7, cortisone acetate⁸ or cyclophosphamide^9–11 have been found to limit the bursa-dependent antibody system. Infectious bursal disease (IBD), formerly known as Gumboro disease, is a naturally occurring virus disease of young chickens¹², characterized by the destruction of the lymphoid tissue in the bursa without repopulation¹³. The disease has been reported from many countries in Europe and in North America. The effect of IBD on the course of other infections in the chicken is therefore of interest. We report here that the primary and secondary serological responses to Newcastle disease vaccine were reduced significantly in chickens which were experimentally inoculated with the infectious bursal agent (IBA) at one day of age.     

An assessment of a natural wetland receiving sewage effluent

An assessment of the performance of a wetland dominated by opportunistic weeds in removing nutrients from a secondary sewage effluent was carried out at Thredbo in Kosciusko National Park. Water quality sampling of the inflow and outflow showed a reduction in turbidity, pH and conductivity with passage through the wetland. Dissolved oxygen levels also decreased. In summer 1982, the phosphorus toad of 1.8 kg P day^-1 was reduced by 44% as wastewater moved through the wetland, and the nitrogen load of 6.4 kg N day^-1 by 65%. Winter retentions were 10% and 14% of inflowing loads, respectively. In 1983 there was a net release of phosphorus and reduced retention of nitrogen. This was regarded as being a result of physical disturbance of the wetland. Vegetation downstream of the effluent inflow was dominated by the opportunistic weeds Epilobium sarmantaceum and Rumex crispus. Upstream, Carex gaudichaudiana and Baeckea gunniana dominated. Marked seasonal changes in vigour and biomass were recorded. Plants, but not sediments, downstream of the inflow contained more nutrients than those upstream. Seed bank analysis showed more seeds downstream than upstream. A moist treatment promoted more seed germination than a flooded treatment. E. sarmantaceum and to a lesser extent R. crispus dominated in each treatment. In an effort to promote greater water retention and replacement of the weed species, channels in the wetland have been blocked with gravel and planted with Phragmites australis and Schoenoplectus validus.     

Ecological cues, gestation length, and birth timing in African buffalo (Syncerus caffer)

We examined annual variation in the timing of conception andparturition in the African buffalo (Syncerus caffer) and thesynchrony of birth timing with resource cues, using 8 yearsof monthly birth, rainfall, and vegetation data, measured asNormalized Difference Vegetation Index (NDVI). Monthly birthshad the strongest significant correlations with NDVI and rainfalllevels 12 and 13 months in the past, respectively. In addition,the synchrony of current year births corresponds most stronglyto the synchrony of the previous year's NDVI distribution. Becausethe gestation period of buffalo has been estimated to be around11 months, these findings suggest that improved protein levels,occurring approximately a month after the first green flushof the wet season, are either a trigger for conception or conceptionhas evolved to be synchronous with correlated environmentalcues that ensure females enter a period of peak body conditionaround the time of conception and/or parturition. With a gestationperiod of approximately 340 days, parturition occurs to takeadvantage of the period when forage has its highest proteincontent. A comparative analysis of gestation periods withinthe subfamily Bovinae indicates that African buffalo have aprotracted gestation for their body size, which we suggest isan adaptation to their seasonal environment. We also found thatinterannual variation in the birth distribution suggests a degreeof plasticity in the date of conception, and variation in thenumber of calves born each year suggest further synchrony ata timescale longer than a single year.