Performance of African elephants (Loxodonta africana) and California sea lions (Zalophus californianus) on a two-choice object discrimination task

This study documents the ability of African elephants (Loxodonta africana) and California sea lions (Zalophus californianus) to perform a two-choice object discrimination task. Both species were able to perform this task. However, California sea lions took fewer trials overall to reach a criterion of 10 consecutively correct responses than did African elephants. The performance of California sea lions did not change significantly during this study. However, African elephants showed a gradual learning of the task, as exhibited by a gradual decrease in the number of trials needed to reach criterion. This performance difference may reflect differences in either visual abilities or cognitive functioning, which in turn may be influenced by either different evolutionary pressures exerted on herbivores and carnivores, or by the context in which visual information is used in the lives of these animals. © 1994 Wiley-Liss, Inc.     

Moderate Prenatal Alcohol Exposure Enhances GluN2B Containing NMDA Receptor Binding and Ifenprodil Sensitivity in Rat Agranular Insular Cortex

Prenatal exposure to alcohol affects the expression and function of glutamatergic neurotransmitter receptors in diverse brain regions. The present study was undertaken to fill a current gap in knowledge regarding the regional specificity of ethanol-related alterations in glutamatergic receptors in the frontal cortex. We quantified subregional expression and function of glutamatergic neurotransmitter receptors (AMPARs, NMDARs, GluN2B-containing NMDARs, mGluR1s, and mGluR5s) by radioligand binding in the agranular insular cortex (AID), lateral orbital area (LO), prelimbic cortex (PrL) and primary motor cortex (M1) of adult rats exposed to moderate levels of ethanol during prenatal development. Increased expression of GluN2B-containing NMDARs was observed in AID of ethanol-exposed rats compared to modest reductions in other regions. We subsequently performed slice electrophysiology measurements in a whole-cell patch-clamp preparation to quantify the sensitivity of evoked NMDAR-mediated excitatory postsynaptic currents (EPSCs) in layer II/III pyramidal neurons of AID to the GluN2B negative allosteric modulator ifenprodil. Consistent with increased GluN2B expression, ifenprodil caused a greater reduction in NMDAR-mediated EPSCs from prenatal alcohol-exposed rats than saccharin-exposed control animals. No alterations in AMPAR-mediated EPSCs or the ratio of AMPARs/NMDARs were observed. Together, these data indicate that moderate prenatal alcohol exposure has a significant and lasting impact on GluN2B-containing receptors in AID, which could help to explain ethanol-related alterations in learning and behaviors that depend on this region.     

Blastoderm degeneration, an early embryonic failure in dwarf Single Comb White Leghorn chickens.

Blastoderm degeneration is an early embryonic lethal condition observed in selected paired matings within a line of dwarf Single Comb White Leghorn chickens that results in a 25% reduction of the hatch of fertilized eggs. The disorder is macroscopically evident at 32 h of incubation by the presence of a small localized indentation on the outer periphery of the expanding blastoderm. The affected blastoderms undergo a series of rapid macroscopic degenerative changes that conclude at about 120 h characterized by the presence of dispersed blastoderm fragments on the surface of the egg's yolk. Microscopically, this embryonic failure appears to manifest itself between Hamburger-Hamilton stages 8 and 9 of development and is characterized by a series of retarded developmental processes: closure of the anterior neuropore, brain vesicle differentiation, somite formation, and cardiac development. The disorder is inherited as an autosomal recessive trait. Attempts to identify factors that influence the disorder have thus far been unsuccessful. The symbol bld is proposed for this recessive gene.     

Selected aspects of female white-faced saki (Pithecia pithecia) reproductive biology in captivity

Little is known regarding the reproductive biology of the white-faced saki. Although sakis have been in zoos since the mid-1970s, little attention has been paid to the reproductive biology of this threatened species. This study describes the results of a 3-year study of the reproduction of the white-faced saki in captivity. Using noninvasive methods to determine levels of estrone conjugates (E₁C) and pregnanediol-3-glucuronide (PdG) in daily urine samples, we have characterized the female reproductive cycle of this species. Nonconceptive ovarian cycles were 16.95 ± 1.57 (SD) days, gestational length was 146.1 ± 5.2 (SD) days, and the length of lactationally induced infertility varied among females but averaged 163 ± 40.6 (SD) days. Attempts to accelerate puberty by pairing a young female with an adult male was without effect. Puberty occurred at 32 months of age in one female. This study provides information that enhances our understanding of the reproductive biology of this species. © 1995 Wiley-Liss, Inc.     

The disparity between homologous chromosomes during DNA replication

When the patterns of replicating chromosome bands of homologous chromosomes within a diploid cell during DNA synthesis phase are compared, the frequency of disparity (i.e. a band present on only one homologue) is less than expected on the basis of chance. This could be taken as implying some “link” between homologues which constrains their programmes of replication to keep in step.This paper develops a model showing that the observed disparities can be accommodated within a framework of homologue independence. Differences between cells in the time of appearance of bands lead in any sample to the summation of an infinitude of binomial distributions and hence to over-dispersion.The model fits observed data for bands replicating in euchromatic and heterochromatic chromosome regions obtained from Syrian hamster fibroblast cells growing in vitro.     

Improved Method for the Purification of Biologically Active Transcobalamin II

Transcobalamin II (TC II) was purified about 300, 000-fold from Cohn fraction III using a modification of the procedure described by Allen and Majerus (J. Biol. Chem. 247, 7709–7717 (1972)). The simplified method incorporated isoelectric precipitation of the TC II into the purification scheme which permitted the elimination of two colimn chromatographic steps originally reported by the above worke-s. The final preparation had 26.7 jjg of vitamin B, ～ (B₁₂) bound per mg of protein and an A₂₈₀/A₃₆₁ ratio of 2.05, both of which are in good agreement with the reported values. The purified TC II was biologically active with respect to its ability to facilitate penetration of B₁₂ into lleLa cells in tissue culture.     

Sand and nest temperatures and an estimate of hatchling sex ratio from the Heron Island green turtle (Chelonia mydas) rookery, Southern Great Barrier Reef

Sand and nest temperatures were monitored during the 2002–2003 nesting season of the green turtle, Chelonia mydas, at Heron Island, Great Barrier Reef, Australia. Sand temperatures increased from ∼ 24°C early in the season to 27–29°C in the middle, before decreasing again. Beach orientation affected sand temperature at nest depth throughout the season; the north facing beach remained 0.7°C warmer than the east, which was 0.9°C warmer than the south, but monitored nest temperatures were similar across all beaches. Sand temperature at 100 cm depth was cooler than at 40 cm early in the season, but this reversed at the end. Nest temperatures increased 2–4°C above sand temperatures during the later half of incubation due to metabolic heating. Hatchling sex ratio inferred from nest temperature profiles indicated a strong female bias.