John F. Anderson

Responses to Starvation in the Spiders Lycosa Lenta Hentz and Filistata Hibernalis (Hentz)

Effects of starvation were investigated in two species of spiders to gain insight on how these predators deal with an unpredictable food supply. Comparison of weights and body dimensions of individuals from field populations with those of known nutritional status showed that lack of food is a problem for field populations of both species. Adult survival times under starvation conditions averaged 208 days for the wolf spider, Lycosa lenta, and 276 days for the cribellate web-builder, Filistata hibernalis. Potential adult life spans for fed individuals were estimated to be 305 days for L. lenta and several years for F. hibernalis. Both spiders have metabolic rates significantly lower than those of other poikilotherms of similar size, and when starving, reduce their metabolic rates by 30% to 40% without any apparent decrease in their normal capabilities. The difference in survival times under starva- tion conditions of the two species was found to be inversely related to metabolic rate. This suggests that the relatively low metabolic rates characteristic of spiders as well as their capacity to reduce these rates when starving are adaptive in survival where prey are scarce. That starved individuals have the capacity to double their body weight through ingestion of large amounts of food when available may be an adaptation to their predation.

Respiratory Gas Exchange in Spiders

The functional characteristics of the respiratory gas exchange systems of spiders were evaluated from relationships describing respiratory surface areas, lung volumes, rates of oxygen consumption, and heart rates as functions of change in body size. Most spiders have rates of metabolism lower than those of other poikilotherms: Those spiders with the lowest rates are adapted to live in environments characterized by low energy availability. Rates of metabolism are directly proportional to respiratory surface area and are positively correlated with lung volume. Modification of respiratory or circulatory variables potentially provides for aerobic scopes of three- to eightfold. These estimates agree with those reported for spiders based on measurements of rates of metabolism. These aerobic scopes for spiders are lower than those reported for insects. This comparison underscores the adaptive characteristics associated with the sit and wait style of predation in spiders. Their use of silk snares and poison to capture prey as well as their well-developed anaerobic capacity and ability to disperse passively by ballooning alleviates the necessity for high aerobic capabilities.

A rapid chromatographic strip test for the pen-side diagnosis of rinderpest virus.

Rinderpest is a contagious viral disease of cloven-hoofed domestic and wild animals. Eradication of the virus following outbreaks depends on rapid and accurate diagnosis of infection and the implementation of control measures. Reporting and confirmatory diagnosis precede the implementation of control measures. A number of techniques have been used for diagnosis such as agar gel immunodiffusion, enzyme-linked immunosorbent assay (ELISA), molecular biological techniques such as polymerase chain reaction (PCR) and virus isolation in tissue culture. Many of these methods are both time consuming and require skilled personnel. The development of a rapid pen-side test for the detection of rinderpest virus (RPV) antigen in lachrymal fluid of cattle is described using the Clearview chromatographic strip test technology (Unipath, Bedford). Optimum conditions for binding monoclonal antibody to nitrocellulose and latex microspheres were determined and a prototype device was developed. The device detected viral antigen in lachrymal fluids from experimentally and naturally infected cattle and showed no cross-reactivity with other related viruses. A field trial was carried out at the Landhi Cattle Colony (LCC), Pakistan, to assess the performance of the rinderpest test under field conditions. Ninety-seven animals, some of which were showing various clinical signs, at LCC and neighbouring colonies were sampled and tested at the pen-side by Clearview and later by immunocapture ELISA (IC-ELISA) at IAH, Pirbright. Nineteen animals were positive by Clearview and/or IC-ELISA. Seventeen out of 19 rinderpest positive animals were positive by Clearview and 15 out of 19 were positive by IC-ELISA. Reverse transcription polymerase chain reaction (RT-PCR) confirmed the 19 animals to be rinderpest positive. This simple, rapid, specific test allows for the first time, accurate pen-side diagnosis of rinderpest.

The fluid pressure pumps of spiders (Chelicerata, Araneae)

SummaryThe identity of the fluid pressure pumps in spiders was investigated in Filistata hibernalis through measurements of the activity of certain muscle groups, leg movements, and changes in fluid pressure within the leg. Our results indicate the cephalothorax is the site of the pressure pump responsible for leg extension and the musculi laterales are the major muscles involved in the operation of this pump. Fluid pressures in the legs averaged 5 100 N·m−2 in resting spiders, ranged from 4 000 to 6 700 N·m−2 in walking spiders and reached as high as 61000 N·m−2 in startled spiders. Intra-abdominal fluid pressures were also measured and found to be much lower, ranging from 1000 to 4 000 N· m-2. These pressures are the result of activity of at least two sets of abdominal muscles, the sub-cuticular muscle sheet and the paired series of dorso-ventral muscles. We suggest the abdominal fluid pressure and the rigidity of the book-lungs attenuate pooling of the hemolymph in the abdomen when the spider is active. Finally we hypothesize that evolution of the hydrostatic skeleton in spiders has allowed a greater mass of flexor muscles to be incorporated into the legs and this in turn is an adaptation to the spider in prey capture.

Distributional impact of rotavirus vaccination in 25 GAVI countries: estimating disparities in benefits and cost-effectiveness.

BACKGROUNDnOther studies have demonstrated that the impact and cost effectiveness of rotavirus vaccination differs among countries, with greater mortality reduction benefits and lower cost-effectiveness ratios in low-income and high-mortality countries. This analysis combines the results of a country level model of rotavirus vaccination published elsewhere with data from Demographic and Health Surveys on within-country patterns of vaccine coverage and diarrhea mortality risk factors to estimate within-country distributional effects of rotavirus vaccination. The study examined 25 countries eligible for funding through the GAVI Alliance.nnnMETHODSnFor each country we estimate the benefits and cost-effectiveness of vaccination for each wealth quintile assuming current vaccination patterns and for a scenario where vaccine coverage is equalized to the highest quintiles coverage. In the case of India, variations in coverage and risk proxies by state were modeled to estimate geographic distributional effects.nnnRESULTSnIn all countries, rates of vaccination were highest and risks of mortality were lowest in the top two wealth quintiles. However countries differ greatly in the relative inequities in these two underlying variables. Similarly, in all countries examined, the cost-effectiveness ratio for vaccination (

Development of a genetically marked recombinant rinderpest vaccine expressing green fluorescent protein

/Disability-Adjusted Life Year averted, DALY) is substantially greater in the higher quintiles (ranging from 2-10 times higher). In all countries, the greatest potential benefit of vaccination was in the poorest quintiles. However, due to reduced vaccination coverage, projected benefits for these quintiles were often lower. Equitable coverage was estimated to result in an 89% increase in mortality reduction for the poorest quintile and a 38% increase overall.nnnCONCLUSIONSnRotavirus vaccination is most cost-effective in low-income groups and regions. However in many countries, simply adding new vaccines to existing systems targets investments to higher income children, due to disparities in vaccination coverage. Maximizing health benefits for the poorest children and value for money require increased attention to these distributional effects.

The physiology of exercise at and above maximal aerobic capacity in a theraphosid (tarantula) spider,Brachypelma smithi (F.O. Pickard-Cambridge)

In order to effectively control and eliminate rinderpest, a method is required to allow serological differentiation between animals that have been vaccinated and those which have recovered from natural infection. One way of doing this would be to engineer the normal vaccine to produce a genetically marked rinderpest virus (RPV) vaccine. We constructed two modified cDNA clones of the RPV RBOK vaccine strain with the coding sequence of the green fluorescent protein (GFP) gene inserted as a potential genetic marker. RPVINS-GFP virus was designed to produce independent and high level expression of GFP inside infected cells, whilst the GFP expressed by RPVSIG-GFP virus was designed to be efficiently secreted. Infectious recombinant virus was rescued in cell culture from both constructs. The effectiveness of these viruses in stimulating protective immunity and antibody responses to the marker protein was tested by vaccination of cattle and goats. All of the vaccinated animals were completely protected when challenged with virulent virus: RPV in cattle or peste-des-petits ruminants virus in the goats. ELISA showed that all of the animals produced good levels of anti-RPV antibodies. Three of the four cattle and the two goats vaccinated with RPVSIG-GFP produced detectable levels of anti-GFP antibodies. In contrast, no anti-GFP antibodies were produced in the four cattle and two goats vaccinated with RPVINS-GFP. Therefore, secretion of the GFP marker protein was absolutely required to elicit an effective humoral antibody response to the marker protein.

Energy content of spider eggs

SummaryThe physiology of activity in a large (ca. 30 g) mygalomorph (‘tarantula’) spiderBrachypelma smithi, was investigated for 10 min runs at speeds of 2.0, 2.5, and 5.0 cm/s. No differences inn

The excreta of spiders

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