Cage Conditions Research Articles

Chromosome Stability and Fertility of a Nitrous Oxide‐Derived Tetraploid Population of Red Clover1

The first and sixth generations of a randomly mated, autotetraploid red clover (Trifolium pratense L.) population (2n=28) derived by treatment with nitrous oxide were examined to determine changes in male and female fertility. Characters measured were chromosome pairing, pollen stainability, and seed set. Approximately equal numbers of aneuplolds (2n−1, 2n+1, 2n+2) were observed in each generation tested. These aneuploids produced less stainable pollen and seed than did euploids in greenhouse crosses, but under field cage conditions, only 2n=27 genotypes produced fewer seeds per head than the euploid genotypes (2n=28). However, clones with 27, 28, and 30 chromosomes produced lighter weight seeds than clones with 29 chromosomes. It was concluded that six generations of random mating were ineffective in changing meiotic configurations, pollen stainability, and seed yield. Although not directly compared in this study, aneuploids appeared to be produced in about the same frequency in nitrous‐oxide and colchicine‐derived tetraploid populations. Aneuploids apparently are not a major factor in the low seed yields of tetraploid red clover. It is suggested that direct selection for high seed yield may be more effective than selection for absence of aneuploids.

Efficacy of Dipel and Geocoris punctipes (Hemiptera: Lygaeidae) against the Tobacco budworm (Lepidoptera: Noctuidae) on Cotton1

The efficacy of Bacillus thuringiensis Berliner in combination with Geocoris punctipes (Say) for control of Heliothis virescens (F.) on cotton was studied under greenhouse and field cage conditions. Various rates of B. thuringiensis (141, 282,561, and 1,121 g/ha) were evaluated in combination with predator densities ranging from one G. punctipes nymph per plant to one per four plants. Results indicated potential for good control with rates as low as 282 g of B. thuringiensis per ha and one Geocoris nymph per four plants.

Oviposition Site Preference by the Tomato Fruitworm (Lepidoptera: Noctuidae) on Tomato, with Notes on Plant Phenologyl

Egg counts were made to determine preferred oviposition sites of Heliothis zea (Boddie) on the tomato cultivars ‘VF-J98’ under field cage conditions and ‘VF-198’ and ‘Campbell 82’ under natural conditions. A phenological study of tomato was used to establish an age basis for vegetative and fruiting structures. Moths demonstrated a highly significant preference for oviposition on leaves rather than on blooms, fruit, or stems. No preference was shown for dorsal vs. ventral leaf surfaces. A highly significant relationship existed between proximity of leaves to blooms, with a positive correlation between the number of open flowers and selection of a leaf for oviposition.

Dynamics of oviposition in Danaus plexippus (Insecta: Lepidoptera) on milkweed, Asclepias spp

Where a butterfly chooses to lay an egg will influence the subsequent survival of her offspring. In this paper we report on the effect of a number of variables which influence the choice of oviposition site in Danaus plexippus L. Experiments were conducted under both flight cage and field conditions. The field observations consisted of recording the within and between plant egg dispersions across different patch sizes. Laboratory experiments looked at egg laying preferences as affected by plant species, age and condition. Butterflies were selective in their choice of oviposition site. Eggs were laid singly on the underside of medium sized leaves towards the top of a plant. More eggs were laid per plant on single isolated plants than on plants within a patch. The number of eggs per plant increases with plant height but decreases with plant age. Females preferred young plants or plants with fresh regrowth of leaves. These characteristics could override species preferences which were, in decreasing order, Asclepias curassavica. A. fruticosa and A. physocarpa. Species preferences varied between butterflies and with female age. Neither the presence of eggs nor larvae on a plant deterred oviposition. These results are compared with previous observations of egg laying in this species.

Investigation of the Bruce effect in the Mongolian gerbil (Meriones unguiculatus).

Strange males and females blocked implantation in recently mated female Mongolian gerbils. Even the presence of the partner male failed to annul the influence. The females were, however, affected only when not lactating (e.g. in first pregnancies or when a litter had died). Pregnancies could also be ended by alterations of the caging conditions, but there were quantitative differences between social and non-social influences, both in numbers of females reacting and in their subsequent fertility. These results with gerbils do not support the suggestion that the biological advantage of pregnancy blocking lies in enhanced male reproductive success.

Further tests on Ceutorhynchus trimaculatus F. as a candidate for the biological control of Carduus thistles

Tests were conducted on Ceutorhynchus trimaculatus F. (Coleoptera: Curculionidae), a candidate for introduction from Europe into North America, for the biological control of Carduus thistles which are major weeds in pastures, rangeland and interstate highway embankments. Host specificity tests conducted simultaneously in Blacksburg, Virginia and in Albany, California were to determine whether Cirsium species native to the USA, and considered to be endangered species, are acceptable as hosts to the weevil, and if there is any preference for the Cirsium over the Carduus thistle species. In Virginia, three Cirsium species were compared with Carduus thoermeri Weinmann (musk thistle) and, in California, four Cirsium species were compared with Carduus macrocephalus L. Adult weevils fed on all test species, to a greater extent on musk thistle than on the Cirsium spp. except for Cirsium discolor (Muhl.) Spreng. which was preferred to musk thistle. Cirsium arvense (L.) Scop., Cirsium discolor and musk thistle supported oogenesis of Ceutorhynchus trimaculatus , but the greatest number of eggs was in musk thistle. Ovipositional preference was also shown for musk thistle over the Cirsium spp. in comparison tests using leaf bouquets, although no distinct preference for oviposition on rosettes was found. Besides musk thistle, both Cirsium occidentale (Nutt.) Jepson and Cirsium brevistylum Cronq. supported development from first instar to the adult stage. These results indicate that several of the Cirsium species tested are acceptable as hosts of Ceutorhynchus trimaculatus under caged conditions. However, musk thistle was preferred for feeding, oogenesis and oviposition.

The nocturnal behavior of caged rhesus monkeys (Macaca mulatta).

The behavior of rhesus monkeys (Macaca mulatta) was observed via videotape recording during the 12 hour period from 6.00 p.m. to 6.00 a.m. Adult animals were housed in male/female pairs under one of three cage conditions: individual cage, mating cage and a larger 'group' cage. 20 categories of behavior were assessed and the resultant behavior was described and quantitatively compared across cage conditions. The animals spent almost the entire night in a sitting position, either alone or while huddling with another animal. Sitting and huddling behavior are near-perfect complements to each other in terms of the frequency of occurrence; taken together they account for almost the entire nocturnal behavior. Other activity rarely displaces these behaviors. The animals tended to be relatively active in the early evening. As night fell, they settled down to relative inactivity, which they maintained until the morning. The activity level gradually increased as dawn approached.

Infant rat hyperactivity elicited by home cage bedding is unaffected by neonatal telencephalic dopamine or norepinephrine depletion

Newborn rats received either stereotaxically guided bilateral injections of 6-hydroxydopamine (6-OHDA) in the neostriatum so as to deplete dopamine (DA) there, or subcutaneous 6-OHDA to deplete forebrain norepinephrine (NE). Both the DA and NE depleted rats as well as their respective control rats were significantly more active at 15-16 days of age when tested in a novel environment containing soiled bedding from their home cages, than when tested in the presence of clean bedding material. Furthermore, under both the home cage and clean bedding conditions the DA depleted rats were more active at this age than their controls. Thus while transiently elevated locomotor activity is one consequence of neonatal, neostriatal DA depletion, inattention to olfactory stimuli (which occurs after adult neostriatal DA depletion) is not another. The NE depleted rats in both home cage and clean bedding test conditions showed activity levels equivalent to that of their control groups. Furthermore, the NE depletion did not affect hyperactivity elicited by artificially (peppermint) scented bedding like that in which the rats had been reared. Thus, contrary to expectations based on the reported reduction of preference for conspecific odor after neonatal and adult forebrain NE depletion, these data show that the locomotor activating effects of neither conspecific nor artificial odors associated with the nest odors are attenuated by neonatal NE depletion. The mortality rates among NE depleted rats raised in the peppermint scented shavings was unusually high and overall, these rats were less active than similarly raised controls.

Mother-infant relationship in the slender loris (Loris tardigradus lydekkerianus)

Close observations under caged conditions were made on the behaviour of four mother lorises towards their own and alien infants. There appears to be no mutual recognition between the mother and her infant, and the relationship appears to be less specific. The infants are accepted by and get settled with any lactating female. In the first few weeks after birth, there is an intense attachment exhibited by the mother towards her baby. When the baby is separated, it exhibits a series of “fixed action patterns.” As the infant grows older, maternal interest declines and is lost after about 15–20 weeks post partum.

Parturition in the slender loris (Loris tardigradus lydekkerianus)

The process of the birth of an infant slender loris has been observed under caged conditions—probably for the first time. The total time taken for the complete emergence of the fetus was 4 min and 34 sec. Three hours and 4 min later, the placenta was expelled and was completely devoured by the mother. Both head and breech presentations are normal and involve no manipulation from the mother. Detailed observations have been made on the pre-parturitional and post-parturitional changes in the mother.

Genetic instability in mass-rearing colonies of a sex-linked translocation strain of Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) during a field trial of genetic control

Genetic breakdown occurred in a strain of Lucilia cuprina constructed for the purpose of genetic control of this pest. The strain incorporated autosomal recessive eye colour mutations linked in repulsion with a translocation involving the Y chromosome (male-determining) and two autosomes. In the original strain females had white eyes and males were wild type. The spontaneous breakdown involved a failure of the sex-limited inheritance of the eye colour mutations. Characteristically the frequency of white-eyed males increased rapidly in the strain, whereas the frequencies of the three other phenotypically recognizable breakdown products did not. This suggested that the white-eyed males had a selective advantage over both the wild type males and the other breakdown products. Genetic analysis revealed that recombination, which is normally rare in L. cuprina males, is considerably more frequent in the presence of a Y-autosome translocation, but that recombination alone was insufficient to account for the rate of increase of the white-eyed males in the colony. Genetic and cytological analysis of the breakdown products revealed that reversion of the multi-break translocation also occurred, and that many of the white-eyed males had either only a Y-single-autosome translocation or no translocation at all; thus these males were more fertile than the wild type multi-translocation males. In addition, under colony cage conditions the white-eyed males may have had a behavioural advantage in competition with the wild type males.

Videotape observation of rats and mice during an exposure to 2450‐MHz microwave radiation

Rats and mice were observed in a microwave field to see if they would take behavioral action to minimize absorption of microwave energy by altering their orientation with respect to the E field. Individual rats were housed either in a cylindrical or in a cuboidal container, and mice were housed in a cuboidal container. They were placed in an anechoic chamber at 22 or 28°C for a one‐hour pre‐exposure period. During the second hour, animals were exposed to 2450‐MHz CW microwaves under far‐field conditions at a power density of 15 mW cm−2. Videotape samples of their positions were taken during a two‐hour session. Six rats and six mice were observed at each level of temperature and were scored for orientation relative to the electric vector or to the magnetic vector of the microwave field. Results indicate that 2450‐MHz CW microwaves did not cause animals to alter their position from that adopted in response to environmental or caging conditions. The specific absorption rate (SAR) in rats was not dependent on their orientation in the field. The SAR in mice was dependent on their orientation in the field but their orientation did not show changes interpretable as attempts to reduce microwave absorption. Containers reduce the SAR and, depending on shape, may reduce the orientation‐dependence of the SAR.

Potentiation of warfarin toxicity to roof rats (Rattus rattus) by L‐histidine and by vitamin K adsorbers

AbstractThe efficacy of warfarin alone or with various additives was tested against roof rats (Rattus rattus). Warfarin alone at 50 mg kg−1 of bait killed 37% of the roof rats where‐as the additives, L‐histidine (40 mg kg−1 of bait), activated‐clay, charcoal and carbon (10 g kg−1 of bait), tested individually, produced no mortality. However, when warfarin wascombined with each of these additives in turn, only the L‐histidine combination resulted in 100% mortality while the other combinations killed 88, 75 and 63% of the test rats respectively. Further trials of paired comparison tests were carried out in order to evaluate the efficacy of the warfarin/L‐histidine combination under different environmental conditions. All the rats succumbed to this combination in both cage and rattery conditions when there was no alternative food. Mortality decreased to 60% in cage and 70% in rattery when alternative food was provided alongside the poison bait. Rats tended to die more quickly with the L‐histidine combination than with warfarin alone. Field trials also confirmed that this combination was effective in reducing roof rat infestations as shown by the yield of corpses, the post‐poison bait intake and post‐operational surveillance.

Effects of basolateral amygdaloid lesions on schedule induced and schedule dependent behavior

Rats were reduced to 80% body weight and were exposed to an FI-1 min food reinforcement schedule for 30 min daily until lever presses, licks, and water consumption stabilized for at least 10 days. Bilateral lesions were then made in the basolateral amygdala of all animals. Animals were tested for 40 days following the lesions at 80% body weight, were permitted to recover body weight by increasing food rations, and were tested for an additional 15 days under ad lib feeding. Animals were then subjected to the following tests: food consumption following food deprivation, drinking following water deprivation, and salt arousal of drinking. In addition, consumption of 6.85% sucrose, 25% sucrose, 8% glucose, 21% glucose, and 0.125% Na saccharin on a FI-1 min food reinforcement schedule and under home cage conditions were measured. On the basis of these data and lesion locus the 8 animals were divided into 2 groups, bilaterally symmetrical experimentals and asymmetrical controls. Although no effects were observed in licking, water consumption, and lever pressing, animals with bilateral symmetrical lesions of the basolateral amygdala displayed relatively permanent deficits in their responses to various taste stimuli. The effects of these lesions are evaluated and discussed in terms of the lateral hypothalamic involvement in schedule induced and schedule dependent behavior.

Thirty-eight blood, tissue and consumptive measures from rats exposed perinatally and as adults to 0.5 Hz magnetic fields

In a factorial design, 40 male rats 195 ± 15 days of age that had been exposed: (1) perinatally for 5 days to either 10−6T to 10−3T variation, 0.5 Hz rotating magnetic fields (RMFs) or to sham field conditions, and (2) to one of two typical postweaning caging conditions were exposed for 5 days to either 10−6T, 10−7T, 10−8T, 0.5 Hz RMFs or sham fields (<10−9T variation in an experimental room) or to colony room control conditions. Consumptive behaviors, selected tissue weights, differential white blood cell counts and 20 constituents from blood sera (analyzed by sequential multiple analyses computer) were measured. Except for marginally significant differences in Na, Cl, and Ca, there were no significant differences between adult RMF intensities for any of the measures; a significant caging by adult intensity interaction was noted for GOT. Rats that had been exposed to the experimental room (continuous noise and light) displayed significant decreases in serum albumin, globulin, glucose and phosphorus levels as well as food and water consumption. Rats that had been exposed perinatally to the RMFs displayed significant 20% reductions in UREA, GOT, and LDH activity, 4% increases in testicle weights and 17% decreases in thymus weights relative to perinatal sham field controls. The absence of significant perinatal condition by adult condition interactions did not support the hypothesis that perinatal RMF exposure might enhance responsiveness to more natural, less intense field variations. Caging differences were associated with highly significant alterations in body weight, several tissue weights, Na, Ca, protein, cholesterol, triglycerides, glucose, CO2 and LDH.

Thymus mast cells numbers following perinatal and adult exposures to low intensity 0.5 Hz magnetic fields.

In a factorial design, 40 male 200-day-old rats that had been exposed from 2.5 days before to 2.5 days after birth to either 0.5 Hz rotating magnetic fields (RMFs) between 10−3T to 10−6T or to sham fields and maintained after weaning in one of two typical caging conditions were exposed as adults to either one of three 0.5 Hz RMF intensities (10−6T, 10−7T or 10−8T) or to sham fields or to colony room control conditions. The numbers of mast cells (MCs/mm2) were determined for thymus tissues stained with thionin and toluidine blue. Thymuses from adult rats that had been perinatally exposed to the RMF displayed a marginally significant 20% to 35% elevation in MC numbers relative to sham-field controls. However the adult exposures did not significantly affect the MC numbers. The two postweaning caging conditions, a non-magnetic field comparator variable, induced a significant 35% difference in MC numbers. The absence of significant perinatal by adult RMF exposure interactions indicated that early magnetic field exposure did not alter adult thymus responsivity to weaker but more natural intensity levels.

Effects of thalamic taste nuclei lesions on the ingestion of sapid solutions and schedule induced and schedule dependent behavior

Abstract Rats were reduced to 80 percent body weight and were exposed to an FI-1 min food reinforcement schedule for 30 min daily until lever presses, licks, and water consumption stabilized for at least 10 days. Bilateral lesions were then made in the thalamic taste nucleus of all animals. Animals were tested for 50 days following the lesions at 80 percent body weight, were permitted to recover body weight by increasing food rations, and were tested for an additional 30 days under ad lib feeding. Animals were then subjected to the following tests: food consumption following food deprivation, drinking following water deprivation, salt arousal of drinking, and drinking of 7°C water following water deprivation. In addition, consumption of 6.85% sucrose, 25% sucrose, 8% glucose, 21% glucose, and 0.125% Na saccharin on a FI-1 min food reinforcement schedule and under home cage conditions were measured. On the basis of these data and lesion locus the 8 animals were divided into 2 groups, bilaterally symmetrical experimentals and asymmetrical controls. Although only transient effects were observed in licking, water consumption, and lever pressing, animals with bilateral symmetrical lesions of the medial ventral thalamic nuclei displayed relatively permanent deficits in their responses to various taste stimuli and the salt arousal of drinking. The effects of these lesions are evaluated and discussed in terms of the lateral hypothalamic invovlement in schedule induced and schedule dependent behavior.

Thyroid morphology and wet organ weight changes in rats exposed to different low intensity 0.5 Hz magnetic fields and pre-experimental caging conditions.

In eight separate experiments, 48 adult female rats were caged in groups of 3 or 4 individuals under normal lighting conditions for 120–140 days. They were then exposed in pairs to one of 6 different variation intensities (0.001 to 10 G, i.e., 10−7 T to 10−3 T) of a 0.5 Hz rotating magnetic field (RMF) or to one of 3 sham field positions for 10 days while under constant 45 lux illumination. Post-mortem examination and histological analyses demonstrated that RMF-exposed rats show no significant changes in thyroid follicle numbers, perifollicular mast cell numbers, wet adrenal and pituitary weights, body weight changes, or water consumption either between intensity groups or relative to sham field controls. Significant interactions existed for thyroid and spleen weights between exposure intensities and preexposure caging conditions for the 10−5 T to 10−6 T groups; the effect was not linearly related with field intensity. Rats that had been maintained in the 4/cage situation showed significantly lighter body weights and more thyroid follicles; the significant alterations in thyroid, adrenal and spleen weights were related to body weight.

Sources of Variability in Rat Caries Studies: Microbial Infection and Caging Procedure

Two sources of variability in rat caries experiments have been investigated: infection with two S mutans strains and two types of caging. Results indicated that strain 6715 was more virulent than was strain 10449 when 24-day-old rats were orally infected with the organism under standardized conditions. Caging of rats (2 per cage) in stainless steel, raised bottom cages resulted in higher level of caries than in plastic tubs (3 per cage) with hardwood bedding. Infection and caging conditions are two of the factors which may contribute to variability in caries pattern and severity in experimental rats.

Evaluation of caged mating behavior in Macaca fascicularis.

Studies were undertaken to characterize the basic behavioral parameters of a breeding colony of Macaca fascicularis under caged conditions. The female Reproduction Performance Index and the Success Ratio were found to correlate with mating behavior relating to cyclicity in females with cycles of less than 30 days. These evaluations proved to be useful in the selection of animals based on sexual vigor.