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Human and mouse subjects tried to anticipate at which of 2 locations a reward would appear. On a randomly scheduled fraction of the trials, it appeared with a short latency at one location; on the complementary fraction, it appeared after a longer latency at the other location. Subjects of both species accurately assessed the exogenous uncertainty (the probability of a short versus a long trial) and the endogenous uncertainty (from the scalar variability in their estimates of an elapsed duration) to compute the optimal target latency for a switch from the short- to the long-latency location. The optimal latency was arrived at so rapidly that there was no reliably discernible improvement over trials. Under these nonverbal conditions, humans and mice accurately assess risks and behave nearly optimally. That this capacity is well-developed in the mouse opens up the possibility of a genetic approach to the neurobiological mechanisms underlying risk assessment. genetics | human | interval timing | optimality | statistical decision theory

The insertion of two transposon-like DNA sequences in the human prolactin gene, which together function as an alternative promoter directing extrapituitary pituitary hormone prolactin (PRL) expression, is reported. It is supposed that the transposon insertion event has resulted in divergent expression of prolactin in primates, and in differential actions of pituitary versus extrapituitary prolactin in lactation versus pregnancy respectively.

The reference human and chimpanzee genomes are compared to determine the magnitude of the recombination between Alu elements in the human lineage since the human-chimpanzee divergence ~6 million years ago. It is found that Alu recombination-mediated genomic deletion has had a much higher impact than was inferred from previously identified isolated events and that it continues to contribute to the dynamic nature of the human genome.

An overview of function of spalt genes in the development of vertebrates and also diseases in humans is presented.

A comparison of segmental duplications in humans and chimpanzees is presented as they might help in understanding the origins of phenotypic difference between humans and their closest relatives. Comparisons revealed that a total of approximately 80 Mb of segmentally duplicated DNA in humans and 65 Mb in chimpanzees.

This study investigated effects of prolonged submaximal exercise on [Na.sup.+]-[K.sup.+]-ATPase mRNA and protein expression, maximal activity, and content in human skeletal muscle. We also investigated the effects on mRNA expression of the transcription initiator gene, RNA polymerase II (RNAP II), and key genes involved in protein translation, eukaryotic initiation factor-4E (eIF-4E) and 4E-binding protein 1 (4E-BP1). Eleven subjects (6 men, 5 women) cycled at 75.5% (SD 4.8%) peak [O.sub.2] uptake and continued until fatigue. A vastus lateralis muscle biopsy was taken at rest, fatigue, and 3 and 24 h postexercise. We analyzed muscle for [Na.sup.+]-[K.sup.+]-ATPase [[alpha].sub.1], [[alpha].sub.2], [[alpha].sub.3], [[beta].sub.1], [[beta].sub.2], and [[beta].sub.3], as well for RNAP II, eIF-4E, and 4E-BP1 mRNA expression by real-time RT-PCR and [Na.sup.+]-[K.sup.+] -ATPase isoform protein abundance using immunoblotting. Muscle homogenate maximal [Na.sup.+]-[K.sup.+]-ATPase activity was determined by 3-O-methylfluorescein phosphatase activity and [Na.sup.+]-[K.sup.+] -ATPase content by [[sup.3]H]ouabain binding. Cycling to fatigue [54.5 (SD 20.6) min] immediately increased [[alpha].sub.3] (P = 0.044) and [[beta].sub.2] mRNA (P = 0.042) by 2.2- and 1.9-fold, respectively, whereas [[alpha].sub.1] mRNA was elevated by 2.0-fold at 24 h postexercise (P = 0.036) A significant time main effect was found for [[alpha].sup.3] protein abundance (P = 0.046). Exercise transiently depressed maximal [Na.sup.+]-[K.sup.+]-ATPase activity (P = 0.004), but [Na.sup.+]-[K.sup.+]-ATPase content was unaltered throughout recovery. Exercise immediately increased RNAP II mRNA by 2.6-fold (P = 0.011) but had no effect on eIF-4E and 4E-BPI mRNA. Thus a single bout of prolonged submaximal exercise induced isoform-specific [Na.sup.+]-[K.sup.+]-ATPase responses, increasing [[alpha].sub.1], [alpha].sub.3], and [[beta].sub.2] mRNA but only [[alpha].sub.3] protein expression. Exercise also increased mRNA expression of RNAP II, a gene initiating transcription, but not of eIF-4E and 4E-BP1, key genes initiating protein translation. gene expression; RNA polymerase II; 3-O-methylfluorescein phosphatase; [[sup.3]H]ouabain binding

Reproductive cloning is uniformly rejected as a valid technology in humans because of the severely abnormal phenotypes seen in cloned animals. Gene expression aberrations observed in tissues of cloned animals have also raised concerns regarding the therapeutic application of 'customized' embryonic stem (ES) cells derived by nuclear transplantation (NT) from a patient's somatic cells. Although previous experiments in mice have demonstrated that the developmental potential of ES cells derived from cloned blastocysts (NT-ES cells) is identical to that of ES cells derived from fertilized blastocysts, a systematic molecular characterization of NT-ES cell lines is lacking. To investigate whether transcriptional aberrations, similar to those observed in tissues of cloned mice, also occur in NT-ES cells, we have compared transcriptional profiles of 10 mouse NT- and fertilization-derived-ES cell lines. We report here that the ES cell lines derived from cloned and fertilized mouse blastocysts are indistinguishable based on their transcriptional profiles, consistent with their normal developmental potential. Our results indicate that, in contrast to embryonic and fetal development of clones, the process of NT-ES cell derivation rigorously selects for those immortal cells that have erased the 'epigenetic memory' of the donor nucleus and, thus, become functionally equivalent. Our findings support the notion that ES cell lines derived from cloned or fertilized blastocysts have an identical therapeutic potential. expression profiling | nuclear transfer

The preferential occurrence of meiotic recombination at certain regions called hot spots is essential for the generation of genetic diversity and proper segregation of chromosomes during meiosis. The recombination hot spots are the sites for initiation and resolution of both crossovers and conversion events.

The eukaryotic six-subunit origin recognition complex (ORC) governs the initiation site of DNA replication and formation of the prereplication complex. In this report we describe the isolation of the wild-type Homo sapiens (Hs)ORC and variants containing a Walker A motif mutation in the Orc1, Orc4, or Orc5 subunit using the baculovirus-expression system. Coexpression of all six HsORC subunits yielded a stable complex containing HsOrc subunits 1-5 (HsORC1-5) with virtually no Orc6 protein (Orc6p). We examined the ATPase, DNA-binding, and replication activities of these complexes. Similar to other eukaryotic ORCs, wild-type HsORC1-5 possesses ATPase activity that is stimulated only 2-fold by single-stranded DNA. HsORC1-5 with a mutated Walker A motif in Orc1p contains no ATPase activity, whereas a similar mutation of either the Orc4 or Orc5 subunit did not affect this activity. The DNA-binding activity of HsORC1-5, using lamin B2 DNA as substrate, is stimulated by ATP 3- to 5-fold. Mutations in the Walker A motif of Orclp, Orc4p, or Orc5p reduced the binding efficiency of HsORC1-5 modestly (2- to 5-fold). Xenopus laevis ORC-depleted extracts supplemented with HsORC1-5 supported prereplication complex formation and X. laevis sperm DNA replication, whereas the complex with a mutation in the Walker A motif of the Orc1, Orc4, or Orc5 subunit did not. These studies indicate that the ATP-binding motifs of Orc1, Orc4, and Orc5 are all essential for the replication activity associated with HsORC. ATP | replication

The availability of both the mouse and human genome sequences allows for the systematic discovery of human gene function through the use of the mouse as a model system. To accelerate the genetic determination of gene function, we have developed a sequence-tagged gene-trap library of >270,000 mouse embryonic stem cell clones representing mutations in [approximately equal to] 60% of mammalian genes. Through the generation and phenotypic analysis of knockout mice from this resource, we are undertaking a functional screen to identify genes regulating physiological parameters such as blood pressure. As part of this screen, mice deficient for the Wnk1 kinase gene were generated and analyzed. Genetic studies in humans have shown that large intronic deletions in WNK1 lead to its overexpression and are responsible for pseudohypoaldosteronism type II, an autosomal dominant disorder characterized by hypertension, increased renal salt reabsorption, and impaired [K.sup.+] and [H.sup.+] excretion. Consistent with the human genetic studies, Wnk1 heterozygous mice displayed a significant decrease in blood pressure. Mice homozygous for the Wnk1 mutation died during embryonic development before day 13 of gestation. These results demonstrate that Wnk1 is a regulator of blood pressure critical for development and illustrate the utility of a functional screen driven by a sequence-based mutagenesis approach.

The frequency of rare mutant allele and the level of allelic association between this allele and one or several closely linked markers are freqeuntly measured in genetic epidemiology. Both quantities are related to the time elapsed since the appearance of the mutation in the population and the intrinsic growth rate of the mutation (which may be different from the average population growth rate). Here, we develop a method that uses these two kinds of genetic data to perform a joint estimation of the age of the mutation and the minimum growth rate that is compatible with its present frequency. In absence of demographic data, it provides a useful estimate of population growth rate. When such data are available, contrasts among estimates from several loci allow demographic processes, affecting all loci similarly, to be distinguished from selection, affecting loci differently. Testing these estimates on populations for which data are available for several disorders shows good congruence with demographic data in some cases whereas in others higher growth rates are obtained, which may be the result of selection or hidden demographic processes.

The impact of altriciality, allocare and maternal behaviors on the force of selection acting on age-specific survival and fertility in a model that incorporates the dependence of child survival on maternal survival is studied. The main human life-history traits, a high life expectancy and post reproductive life are due to an increase in child altriciality in early humans.