Amount Of Handling Research Articles

Prolonged Storage of Aphid Colonies at Cool Temperatures

Aphids are a valuable tool to study plant vascular tissue and plant responses to aphid feeding. A standard method of rearing aphids for use in education and research is to maintain active cultures in a greenhouse. While some studies have examined ways of providing long-term storage of parasitoids and pathogens of aphids, little has been done to lengthen the time aphids can survive without the need for researchers to provide the aphids with fresh host plants or to maintain the plants with water and fertilizer. Actively reproducing aphid colonies and their host plants must be replaced frequently to prevent overcrowding or colony collapse resulting from degradation of the quality of the plants feeding the colony. This arrangement may not be available for small-scale studies and is costly and cumbersome for multiple lines of aphids. Artificial diets are labor intensive, are most useful for providing a controlled environment to carry out tests on aphids, and are rarely, if ever, suitable for long-term colony survival. Issues present in actively growing cultures can be minimized. By reducing the amount of handling and providing only the small, easily sealed opening of a test tube for access to the aphids, colony contamination from other mobile aphids can be reduced. For example, contamination often occurs with bird cherry aphids (Rhopalosiphum padi L.) which have been noted as adept escape artists (Austin et al., 1991). By using cool temperatures to slow aphid reproduction, the occurrence of problems associated with parasitic wasps and predators such as lady beetles and spiders would also be reduced since threshold temperatures (roughly, the temperature at which development ceases) for parasites is generally higher than that of their hosts (Campbell et al., 1974). The cooler temperatures needed for prolonged aphid survival is not a concern for freezing injury of the plant: threshold temperatures for five different aphid genera ranged from 1.7 to 8.3uC (Campbell et al., 1974) while wheat and barley are killed at temperatures in the 220 to 210uC range (Metcalf et al., 1970). Long-term storage would also increase the number of lines that could be reared with a limited amount of resources. Previous work with greenbugs (Schizaphis graminum Rondani) and Russian wheat aphids (Diuraphis noxia Mordvilko) demonstrated the possibility of cultivating aphids in a test tube for at least four days (Miller et al., 1994). Other systems have been developed for maintenance of aphid colonies for at least a week (Austin et al., 1991) and in Europe an informal method allows for two-week storage in a cold room setting (S. Vidal, pers. comm.). This research was designed to develop an inexpensive test tube culture system for long-term (several week) aphid culture and storage that would not require maintenance or upkeep during the culture period. Materials and Methods S. graminum Biotype E cultures were obtained from USDA/ARS Wheat, Peanut and Other Field Crops Research Unit in Stillwater, OK, USA. R. padi were local, found in our own greenhouse in Stuttgart, AR, USA. Wheat seedlings, cv Ranger, were grown for host plants in a 1:1 (v/v) mix of silt-loam field soil and commercial potting soil in the laboratory under grow lights. Active aphid cultures were maintained on wheat plants and isolated by enclosure in a zippered net bag in order to minimize colony mixing, parasitism, and predation. To establish aphid cultures, three wheat plants approximately 15 cm tall with root and soil still attached were transplanted into a 2.0 3 15.0 cm glass test tube. The soil was moistened by adding enough water to saturate the soil but leave no free water. The tubes were maintained at room temperature (24uC) for two

Approach and follow behaviour – possible indicators of the human–horse relationship

The aim of our study was to analyze the behavioural responses of horses (N = 51) to familiar humans and to find factors that may affect these responses in three tests: (1) approach to, (2) standing beside, and (3) following the familiar person. We investigated the impacts of horse-related factors (gender and age) and human-related factors (type of work, housing management, amount of handling, number of handlers and training to follow). Horses with one handler needed less time to approach the human than horses with more handlers. Standing beside the human correlated positively with following. Following was mainly affected by training. According to our results, the number of handlers has an important effect on horses’ responses to familiar humans, especially regarding approach and follow behaviour. However, following behaviour is fundamentally determined by training. Keywords: human–horse interaction; approach; follow

Growth rates of the infaunal bivalve Soletellina alba (Lamarck, 1818) (Bivalvia: Psammobiidae) in an intermittent estuary of southern Australia

Caging and a mark–recapture design were used to estimate the growth rate of the brittle, infaunal bivalve Soletellina alba in the Hopkins River estuary. The growth of both caged and uncaged individuals was monitored at three sites near the mouth of the estuary over 180 days. Growth rates did not differ for caged and uncaged bivalves, or for bivalves subject to different amounts of handling, or between sites. Growth did differ between consecutive time intervals, which was attributable to negligible growth occurring during the colder months of autumn/winter. Comparisons of the condition (as indicated by total mass for length 3) of S. alba were inconsistent between sites for caged and uncaged bivalves and for those subject to different amounts of handling. Soletellina alba is a rapidly growing bivalve with mean growth rates for the three time intervals being 0.04±0.002 mm day −1 in summer, 0.02±0.001 mm day −1 in autumn and 0.03±0.001 mm day −1 from summer to winter. Using existing literature, it was shown that a significant relationship exists between maximum shell length and onset of sexual maturity in bivalve molluscs. This relationship predicts that S. alba should reach the onset of sexual maturity at 15.8 mm length. Therefore, it appears that it may be possible for juvenile S. alba (<1 mm) to grow, reach sexual maturity and reproduce in between annual mass-mortality events caused by winter flooding.

Pathogenesis of sciatic pain: a study of spontaneous behavior in rats exposed to experimental disc herniation.

A new way to study pain in experimental animals without handling of the animals and based on registration of spontaneous behavior using video recordings. To evaluate if experimental disc herniation in the rat may induce changes in spontaneous behavior. The knowledge regarding the basic pathophysiologic mechanisms of sciatica has increased dramatically during the last decade. However, studies have mainly assessed nerve dysfunction rather than pain. Existing methods to study pain generally comprise a certain amount of handling and registration of changes in sensory thresholds. In the present study we introduce a new way to assess pain that focuses on changes in behavior rather than on changes in thresholds. Forty rats were divided equally into four experimental series: sham exposure of the left L4 dorsal root ganglion, exposure of the left L4 dorsal root ganglion and incision of the L4-L5 disc, exposure and slight displacement of the left L4 dorsal root ganglion, and combination of disc incision and displacement. The rats were videotaped the day before surgery and on day 1, 3, 7, 14, and 21 after surgery. Spontaneous behavior was categorized into 10 behaviors and recorded during 20 minutes of observation. Disc incision and displacement per se did not induce any behaviors different from that observed in the sham-operated group. In the series with the combination of disc incision and displacement there was increased focal pain, seen as increased lifting of the hind paw on the operated side and increased rotation of the head toward the operated side. This pain pattern was most pronounced the day after surgery. Fourteen days after surgery there were no detectable differences in behavior between this group and the sham group. At day 21 after surgery, however, another picture of increased immobility and decreased locomotion was seen in this group, possibly indicating more generalized pain. The study demonstrates that it is possible to detect changes in spontaneous behavior after experimental disc herniation. However, such changes may only be seen if disc incision and slight mechanical deformation are combined. This is in agreement with previous clinical and experimental observations. The present model allows for convenient assessment of pain in a way that focuses on spontaneous behavior rather than changes in pain thresholds and that reduces the interference of the researcher and environment on the outcome of the assessment.

Increased expression of transferrin receptor on membrane of erythroblasts in strenuously exercised rats.

This study investigated the effects of strenuous exercise on transferrin (Tf)-receptor (TfR) expression and Tf-bound iron (Tf-Fe) uptake in erythroblasts of rat bone marrow. Female Sprague-Dawley rats were randomly assigned to either an exercise or sedentary group. Animals in the exercise group swam 2 h/day for 3 mo in a glass swimming basin. Both groups received the same amount of handling. At the end of 3 mo, the bone marrow erythroblasts were freshly isolated for Tf-binding assay and determination of Tf-Fe uptake in vitro. Tissue nonheme iron and hematological iron indexes were measured. The number of Tf-binding sites found in erythroblasts was approximately 674,500 +/- 132,766 and 1,270,011 +/- 235,321 molecules/cell in control and exercised rats, respectively (P < 0. 05). Total Fe and Tf uptake by the cells was also significantly increased in the exercised rats after 30 min of incubation. Rates of cellular Fe accumulation were 5.68 and 2.58 fmol. 10(6) cells(-1). min(-1) in the exercised and control rats, respectively (P < 0.05). Tf recycling time and TfR affinity were not different in exercised and control rats. Increased cellular Fe was mainly located in the stromal fraction, suggesting that most of accumulated Fe was transported to the mitochondria for heme synthesis. The findings demonstrated that the increased cellular Fe uptake in exercised rats was a consequence of the increased TfR expression rather than the changes in TfR affinity and Tf recycling time. The increase in TfR expression and cellular Fe accumulation, as well as the decreased serum Fe concentration and nonheme Fe in the liver and the spleen induced by exercise, probably represented the early signs of Fe deficiency.

Management Briefs: Influence of Electroshock on Short-Term Growth of Adult Rainbow Trout and Juvenile Arctic Grayling and Cutthroat Trout

Rainbow trout Oncorhynchus mykiss (330 mm total length) were exposed to pulsed direct current from a Coffelt BP-6 electroshocker for 10 s. Control fish received the same amount of handling but were not shocked. At termination, 35 d after treatment, the control fish had gained an average of 51.3 g (SD, 18.5) and the treated fish had gained 33.7 g (SD, 17.5). The four fish (8.0%) that died during the experiment were all treated fish. The effects of electroshock on growth of juvenile fluvial Arctic grayling Thymallus arcticus and cutthroat trout Oncorhynchus clarki were also examined. These fish were exposed to the same duration of electroshock as described above, After 28 d, average growth in length and weight of electroshocked Arctic grayling was significantly less than that of the control fish. Both the electroshocked cutthroat trout and the control fish lost weight. However, at the end of the study, the weight of the control cutthroat trout was significantly greater than the electrosocked fish, although length was not affected. The long-term effects of reduced growth rate should be further evaluated. Electrofishing is known to cause varying degrees of trauma to fish (Hauck 1949; Collins et al. 1954; Pratt 1954; McCrimmon and Bidgood 1965; Horak and Klein 1967; Spencer 1967; Maxfield et al. 1971; Schreck et al. 1976; Whaley et al. 1978; Hudy 1985; Sharber and Carothers 1988). Broken backs are the most common form of permanent injury noted in large salmonids. Although electroshocking causes some mortality, the effects of nonlethal trauma have not been fully evaluated.

Effects of early handling on heifers' subsequent reactivity to humans and to unfamiliar situations

The influence of early handling on the behavioural and physiological responses of Friesian heifers to unfamiliar situations and human manipulation was studied. Forty abimals were used. The animals were reared in 4 groups of 10, under standard artificial husbandry conditions. Animals of one group (control animals) were handled only in respect of the demands of normal husbandry. Experimental animals were subjected to additional handling, which consisted of brushing twice a day and leading with a halter. All handled animals received the same amount of handling (30 days) but at different periods in life: 3 days/week from 0 to 3 months of age (Group 0–3); 3 days/week from 6 to 9 months of age (Group 6–9); or 3 days/month from 0 to 9 months of age (Group –9). When the animals were 15 months old, each heifer, from each treatment group, was tested individually and once only in a set of behavioural tests designed to investigate fearfulness (in the presence or absence of human contact) and the ease with which the animal could be handled. Animals from Group 0–9, and to a lesser extent those from Group 6–9, were less reactive than controls in tests involving the presence of a human. However, in most cases Group 0–3 animals did not differ significantly from controls. Thus, it would appear that only prolonged handling during early life substantially influences man-animal relationships. In the fear-eliciting tests, which did not involve human contact, only the responses of Group 0–9 animals differed significantly from those of the controls. It is suggested that temporary prolonged handling influences the expression of fear responses in heifers.

Chapter 15 A Simple Device and Procedure for Successful Freezing of Cells in Liquid Nitrogen Vupor

Cell preservation at low temperatures has become an essential practice in cell biology, particularly in laboratories working with tissue cultures. Sufficient experience has been gained in the practical technology of cryobiology to permit highly successful preservation of cell suspensions. Some of the freezing equipment that has been used for cell freezing includes sophisticated controllers. For the laboratory that only occasionally is required to freeze cells, the use of elaborate and expensive equipment would likely not be justified. Alternative approaches involve the placing of ampoules for timed periods in Dry-Ice chests or Dry-Ice-ethanol mixtures. Other freezing methods involve direct cooling in vapor or liquid nitrogen. In another approach, a mechanical freezer or liquid nitrogen is used to cool an ethanol bath containing the ampoules. While many of the various methods mentioned are reasonably effective, the recovery rate varies largely, according to the rate of initial freezing. The methods also differ in cost, sophistication and automation, amount of handling, and reproducibility of results. The cell freezer to be described has a number of attractive features that appeal to cell biologists and others working with isolated cell suspensions, especially where there is an infrequent need to freeze cells.

EXTENDED ACQUISITION TRAINING AND RESISTANCE TO EXTINCTION.

A group of rats receiving 184 food rewarded, runway acquisition trials extinguished faster than groups receiving only 64 acquisition trials. This was found to be the case whether or not the groups receiving different numbers of acquisition trials were equated prior to extinction with respect to such variables as age, amount of handling, and length of time on deprivation schedule. The results corroborate previous findings by North and Stimmel on the effects of extended acquisition training, and indicate that their results cannot be attributed simply to the age, handling, and deprivation variables. It is a commonly held position, supported by a variety of studies (e.g., Perin, 1942; Williams, 1938), that resistance to extinction in an instrumental reward situation is an increasing monotonic function of the number of acquisition trials. A recent investigation, however, provides evidence that extended acquisition training can lead to decreased resistance to extinction. North and Stimmel (1960) found that rats given 90 or 135 acquisition trials in a straight runway extinguished faster than rats given 45 acquisition trials. The design of this experiment, however, was such that the various groups started training at the same time, and consequently started extinction at different times. Hence, such variables as age, amount of handling, and length of time on deprivation schedule before extinction were confounded with number of acquisition trials. The present study was designed to evaluate the importance of these variables in studies of overlearning, as well as to determine the reproducibility of the effect reported by North and Stimmel.

Bacteriologic studies in ligated and nonligated umbilical cords

A bacteriologic study was conducted on newborns, employing two groups: (1) 88 cases of nonligated cords, and (2) 63 cases of ligated cords. The method has been described in detail, including the handling of the umbilical cord and that employed in the bacteriologic studies. The bacteriologic findings were divided into four groups: (1) Coagulase-Positive Staphylococci, (2) Intestinal Type Organisms, (3) Respiratory Type Organisms, and (4) Anaerobic Organisms. The incidence of Group 1 within 24 hours was 35 per cent in the ligated group and 57 per cent in the nonligated group, but within 72 hours the incidence in the ligated group rose from 35 per cent to 63 per cent and in the nonligated group dropped from 57 per cent to 45 per cent. Bacteriologic observations on Group III, in nonligated cords, showed that 13 cases which were positive within 24 hours became negative within 72 hours, and in Group IV in nonligated group, all organisms that were positive within 24 hours became negative within 72 hours.We feel that a cord that desiccates rapidly and separates early seems to be less favorable to the growth and maintenance of bacteriologic flora, and finally we feel that the amount of handling and contacts to which the severed cord is exposed is important in its relation to its bacterial flora. It is also felt that there are definite advantages in late severance and nonligation of the umbilical cord.

II. Physical Aspects

In this series of experiments and observations an attempt has been made to measure the relative efficiency or effectiveness of 300 kV and 4 MeV X rays in producing different biological and chemical changes. Relative biological efficiency, or R.B.E., is an expression much, and often loosely, used in present-day radiobiology, but it is seldom defined. We shall define the efficiency of 4 MeV X rays relative to 300 kV X rays by the fraction: When two effects are being compared it is important to keep all other factors as constant as possible and in this series great efforts were made to equalise the effects of extraneous factors. The 300 kV Resomax X-ray machine and the 4 MeV linear accelerator (Miller and Flanders, 1953) on which irradiations were carried out are in adjacent rooms and therefore should differ little in atmospheric conditions. Further, the amount of handling and transport in bringing up the test materials to the X-ray tubes will be practically identical. Much more important may be the influence, on their radiosensitivity, of the age or maturity of the test objects. Whenever these parameters could have an effect, exposures were carried out simultaneously on the two machines. The rate at which radiation dose is delivered is known to be important in some instances; unless there was previous evidence that differences in dose-rate were unimportant, care was therefore taken to ensure that corresponding exposures on the two machines were given at equal dose-rates.

Tools for the Workshop

Aircraft radial engines are normally crated and shipped in a vertical position, and a considerable amount of handling is necessary to turn them into the horizontal position for fitting to an aircraft or on a stand. In order to facilitate this operation, Aero‐contacts Ltd. of Gatwick, Surrey, have produced an engine tilting sling. This has an arched sliding beam which enables the engine to be turned through 90 deg. in the vertical plane. When this has been done the propeller shaft attaching nut can be removed so that the engine can be turned through 360 deg. in a horizontal plane. If necessary the sling will hold the engine in any tilted position within the 90 deg. of travel of the beam.