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Phosphorylated extracellular signal-regulated kinase (pERK) mediates neuronal synaptic plasticity, long-term potentiation, and learning and memory in the hippocampus. In this study, we examined pERK1/2 immunoreactivity and its protein level in the gerbil hippocampus at various ages. In the postnatal month 1 (PM 1) group, very weak pERK1/2 immunoreactivity was detected in the hippocampus. In the CA1 region, pERK1/2 immunoreactivity was considerably increased in the stratum pyramidale in the PM 6 group. Thereafter, pERK1/2 immunoreactivity was decreased. In the CA2/3 region, pERK1/2 immunoreactivity increased in an age-dependent manner until PM 12. Thereafter, numbers of pERK1/2-immunoreactive neurons were decreased. However, in the mossy fiber zone, pERK1/2 immunostaining became stronger with age. In the dentate gyrus, a few pERK1/2-immunoreactive cells were observed until PM 12. In the PM 18 and 24 groups, numbers of pERK1/2-immunoreactive cells were increased, especially in the polymorphic layer. In Western blot analysis, pERK1/2 level in the gerbil hippocampus was increased with age. These results indicate that total pERK1/2 levels are increased in the hippocampus with age. However pERK1/2 immunoreactivity in subregions of the gerbil hippocampus was changed with different pattern during normal aging.

We used trained barn owls to introduce a controlled predation threat to two species of gerbil, Gerbillus allenbyi and G. pyramidum in a system of 2-ha, sandy-substrate field enclosures in the Negev Desert, Israel. Using the principles of optimal density-dependent habitat selection, we estimated several coefficients of population interaction focusing on G. allenbyi. G. allenbyi exhibits strong intraspecific competition. In the absence of owls, G. pyramidum competes with it (α = - 0.35). We estimated the slope of the G. allenbyi victim isocline to be - 0.60. The competitive effect of G. pyramidum disappeared in the presence of owl, although the intraspecific competition remained. Our results indicated that in the presence of owls, the threat of predation overwhelms the cost of interspecific competition.

The foraging decisions of animals are often influenced by risk of predation and by the renewal of resources. For example, seed-eating gerbils on sand dunes in the Negev Desert of Israel prefer to forage in the bush microhabitat and during darker hours due to risk of predation. Also, daily renewal of seed resource patches and timing of nightly foraging activity in a depleting environment play important roles in species coexistence. How these factors influence the timing of gerbil foraging was investigated by quantifying foraging activity in seed resource patches that were experimentally renewed hourly during the night. Gerbils showed strong preference for the safe bush microhabitat and foraged less in response to high levels of illumination from natural moon light and from artificial sources. It is demonstrated here for the first time that gerbils also responded to temporal and spatial heterogeneity in predatory risk through their timing of activity over the course of each night. Typically, gerbils concentrated their activity early in the night, but this changed with moon phase and in response to added illumination. These results can be understood in terms of the nature of patch exploitation by gerbils and the role played by the marginal value of energy in determining the cost of predation. They further show the dynamic nature of gerbil foraging decisions, with animals altering foraging efforts in response to time, microhabitat, moon phase, illumination, and resource availability

We trained barn owls to fly over 2-ha field enclosures containing populations of Gerbillus allenbyi. Each 2-ha plot was divided into two equal parts by a fence with gates allowing easy passage of the gerbils. We varied the number of gerbils in the enclosure and the number of owl flights on each side of the dividing fence. Gerbil foraging activity responded within two hours to the difference in number of owl flights over the subplots. The greater the difference, the more the gerbils shifted their foraging to the subplot with fewer flights. Gerbils did not reduce their total foraging effort but redistributed it between subplots. In the absence of owl flights, gerbils divided their foraging effort equally between the matched subplots. Thus, they appear to seek an ideal free distribution in the two halves of each plot. Therefore, based on the gerbils' distribution of activity in the presence of different numbers of owl flights over the two subplots we estimated the shapes and slopes of the gerbil victim isoclines in the middle and right hand side of the 'gerbil-activity vs number of owl flights' state space. The isoclines were parallel straight lines with slope equal to -0.57. We believe this to be the first estimate of a victim isocline for a population of vertebrates in the field. Using the isodar method of Morris, we also determined that the fitness cost of each additional gerbil, i.e., per capita intraspecific competition among the G. allenbyi, is constant. It does not depend on either owl flight frequencies or G. allenbyi densities. The isodar also shows that the fitness cost of added owl flights does not vary with G. allenbyi population densities.

Various techniques were examined to determine optimum conditions for exsheathing infective larvae of 3 important ruminant parasites (Haemonchus contortus, Ostertagia ostertagi, and Trichostrongylus colubriformis). In repeated experiments, aliquots of 105-106infective larvae, 1-2 mo old, of each parasite were incubated in each of 4 exsheathing media (distilled water, Earle's balanced salt solution + carbon dioxide, nematode washing buffer + carbon dioxide, or sodium hypochlorite) for 1 or 18 hr. In each case, the percentage of larvae exsheathed and infectivity for jirds was determined. Results of these studies indicate that no single exsheathing technique of those studied is optimum for every parasite. In addition, caution must be used in drawing conclusions from in vitro studies using exsheathed larvae because techniques that routinely provide high percentages of exsheathment also appear to reduce viability.

Susceptibility to Gymnophalloides seoi infection was studied in 8 species of animals, including 7 strains of mice; the effects of immunosuppression on susceptibility were examined in C3H/HeN mice. One hundred metacercariae of G. seoi isolated from naturally infected oysters were orally administered to each animal. Worm recovery rate (WRR), worm dimensions, and the number of uterine eggs were obtained at day 3 and day 7 postinfection (PI). Average WRR from gerbils, hamsters, and cats at day 7 PI was 28.0%, 14.2%, and 10.9%, respectively, the former 2 figures of which were significantly higher than the rate of 0.0-4.0% from Sprague-Dawley rats, dogs, ducks, guinea pigs, and chicks. In the case of mice, average WRR at day 7 PI was 12.4% (KK strain), 11.8% (C3H/HeN), 9.6% (ICR), 6.4% (BALB/c), and 6.3% (ddY), respectively; the first 3 figures were significantly higher than the rates from other strains, which were 1.8% (A) and 0% (C57BL/6). At day 3 PI, WRR was much higher in all strains except C57BL/6. Worm maturation was the highest in C3H/HeN mice. Immunosuppression of C3H/HeN mice by injecting prednisolone for 7, 14, or 21 days prior to infection increased WRR at day 7 PI to 27.8%, 33.8%, or 67.5%, respectively. The results show that gerbils, hamsters, cats, and KK, C3H/HeN, ICR, BALB/c, and ddY mice are laboratory hosts that are fairly susceptible to G. seoi infection. In C3H/HeN mice, susceptibility was markedly enhanced by immunosuppression.

GP Dr Gerbo Huisman has called on Cherie Blair to have her baby in his local maternity unit in a bid to save it from closure.Dr Huisman, who practises...

In Strongyloides stercoralis-infected gerbils it had been observed previously that the ratio of first-stage larvae to adult worms decreases after 3 wk of infection. Serum obtained from gerbils after this decrease in fecundity, but before worms were expelled, was transferred passively to other infected gerbils during the peak of worm fecundity. The immune serum caused a significant decrease in the L1/adult ratio but had no effect on the number of uterine eggs, the length, or the intestinal and ovarian ultrastructure of adult worms. Apparently a factor(s) in the immune serum either killed eggs, after oviposition, or the hatched larvae, without damaging the adult worms

\"I tell you, this is fun,\" the patient said to Dr. [Karen Clark-Gerbo] as he flipped through the menu. Clark-Gerbo visited him on her Wednesday morning rounds through Ruby Memorial Hospital here. Clark-Gerbo, who grew up near the Elk River, initially wanted to be an obstetrician, not an internist. But a sequence of events during her first year as a WVU medical resident changed her mind. Clark-Gerbo's mom is a nurse and the recently retired director of nursing at Highland Hospital. She helped Clark-Gerbo get her first job in high school: unit clerk on the neurology ward at Charleston Area Medical Center's General Hospital.

Earlier this year, midwives marched through Lichfield to protest at proposals which would see the facility transferred elsewhere along with kidney dialysis services. Last Tuesday, MP Michael Fabricant (Con, Lichfield) demanded assurances from health secretary Alan Milburn over the future of other facilities at the Victoria. 'Both the Royal College of Midwives and the Royal College of General Practitioners are strongly supportive.'