Homeobox genes in hematopoiesis and leukemogenesis

The effect of cold and warm intermittent antegrade blood cardioplegia, on the intracellular concentration of taurine in the ischaemic/reperfused heart of patients undergoing aortic valve surgery, was investigated. Intracellular taurine was measured in ventricular biopsies taken before institution of cardiopulmonary bypass, at the end of 30 min of ischaemic arrest and 20 min after reperfusion. There was no significant change in the intracellular concentration of taurine in ventricular biopsies taken after the period of myocardial ischaemia in the two groups of patients (from 10.1 +/- 1.0 to 9.6 +/- 0.9 mumol/g wet weight for cold and from 9.3 +/- 1.3 to 10.0 +/- 1.3 mumol/g wet weight for warm cardioplegia, respectively). Upon reperfusion however, there was a fall in taurine in both groups but was only significant (P < 0.05) in the group receiving cold blood cardioplegia (6.9 +/- 0.8 mumol/g wet weight after cold blood cardioplegia versus 8.0 +/- 0.8 mumol/g wet weight following warm blood cardioplegia). Like taurine, there were no significant changes in the intracellular concentration of ATP after ischaemia in the two groups of patients (from 3.2 +/- 0.32 to 2.95 +/- 0.43 mumol/g wet weight for cold and from 2.75 +/- 0.17 to 2.62 +/- 0.21 mumol/g wet weight for warm cardioplegia, respectively). However upon reperfusion there was a significant fall in ATP in both groups with the extent of the fall being less in the group receiving warm cardioplegia (1.79 +/- 0.19 mumol/g wet weight for cold and 1.98 +/- 0.27 mumol/g wet weight for warm cardioplegia, respectively). This work shows that reperfusion following ischaemic arrest with warm cardioplegia reduces the fall in tissue taurine seen after arrest with cold cardioplegia. Accumulation of intracellular sodium provoked by hypothermia and a fall in ATP, may be responsible for the fall in taurine by way of activating the sodium/taurine symport to efflux taurine.     

Functional and evolutionary implications of natural variation in clock genes

Stomach cancer remains the second leading cancer in incidence in Shanghai, China, despite its decline over the past 2 decades. To clarify risk factors for this common malignancy, we conducted a population-based case-control study in Shanghai, China. Included in the study were 1,124 stomach cancer patients (age 20-69) newly diagnosed in 1988-1989 and 1,451 controls randomly selected among Shanghai residents. Usual adult dietary intake was assessed using a comprehensive food frequency questionnaire. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression models. Risks of stomach cancer were inversely associated with high consumption of several food groups, including fresh vegetables and fruits, poultry, eggs, plant oil, and some nutrients, such as protein, fat, fiber and antioxidant vitamins. By contrast, risks increased with increasing consumption of dietary carbohydrates, with odds ratios (ORs) of 1.5 (95% confidence interval [CI] 1.1-2.1) and 1.9 (95% CI 1.3-2.9) in the highest quartile of intake among men (p for trend=0.02) and women (p=0.0007), respectively. Similar increases in risk were associated with frequent intake of noodles and bread in both men (p=0.07) and women (p=0.05) after further adjustment for fiber consumption. In addition, elevated risks were associated with frequent consumption of preserved, salty or fried foods, and hot soup/porridge, and with irregular meals, speed eating and binge eating. No major differences in risk were seen according to subsite (cardia vs. non-cardia). Our findings add to the evidence that diet plays a major role in stomach cancer risk and suggest the need for further evaluation of risks associated with carbohydrates and starchy foods as well as the mechanisms involved.     

Structural differences between the repertoires of mouse and human germline genes and their evolutionary implications

BACKGROUND: Postoperative infection following cholecystectomy poses a significant threat to recovery, with major cost repercussions. Though antimicrobial prophylaxis is commonly practiced, its value - particularly in laparoscopic cholecystectomy - has not yet been adequately documented. METHOD: In a prospective multicenter quality assurance study in 28 German hospitals, an analysis of data collected on 4,477 patients undergoing conventional (n = 1,349) or laparoscopic (n = 3,128) cholecystectomy was performed; 2,217 patients received and 2,260 did not obtain perioperative antibiotic cover. RESULTS: Postoperative infections occurred in a total of 136 patients, with infection rates of 5.0% in those without prophylaxis, 0.8% in those on ceftriaxone, and 1.2% in those on other antibiotic regimens. Patients receiving prophylaxis fared significantly better than those with no prophylaxis in terms of the rate of postoperative wound infections, chest infections, other complications, reoperation and mortality. CONCLUSION: Neither laparoscopic nor conventional open cholecystectomy should be performed without adequate perioperative antimicrobial prophylaxis in future, especially since such measures also reduce hospital stay and hence the costs.     

Axial patterning in the leech: developmental mechanisms and evolutionary implications

The subcutaneous distribution and number of Pacinian corpuscles were studied in ten fresh cadaver hands. They were found to cluster close to nerves and vessels at the metacarpophalangeal joints and the proximal phalanx. The total mean number in the hand was 300 (192-424). The percentage of the total was 44 to 60% in the fingers, 23 to 48% in the metacarpophalangeal area and 8 to 18% in the thenar and hypothenar regions. Corpuscles in palmar skin overlying the distal phalanx were smaller than receptors in the metacarpophalangeal area. The lowest density of corpuscles was along the nerves and vessels of the middle phalanx.     

Expression of sex-specific molecular markers in clones of bipartite allophenic nemertines produced by somatic embryogenesis from Lineus sanguineus male/female chimera fragments

Previous studies had demonstrated that in utero exposure to cocaine produces structural changes in the development of the rabbit's anterior cingulate cortex. Because the anterior cingulate cortex has been proposed to subserve a variety of cognitive processes including associative learning, we investigated the effects of intrauterine exposure to cocaine on the acquisition of the rabbit's classically conditioned nictitating membrane response. Adult, sexually mature rabbits born of dams that had received intravenous injections of either saline or cocaine (4 mg/kg, twice a day) from day 8 to day 29 of gestation were classically conditioned by pairing tone and light CSs with an airpuff US. Rabbits that had been exposed to cocaine in utero demonstrated a more rapid acquisition of CRs to a tone CS but not to a light CS as compared with saline controls. Control experiments indicated that the accelerated learning to the tone CS was not due to sensitization, pseudoconditioning, altered baseline rate of responding, an increased responsiveness to the airpuff US, or to a change in the intensity threshold of the tone CS for elicitation of CRs. We conclude that in utero exposure to cocaine alters the processing of auditory stimuli and this leads to an abnormally rapid acquisition of CRs. It is suggested that this functional consequence of prenatal exposure to cocaine is due to structural abnormalities in anterior cingulate cortex.     

VH gene organization in a relict species, the coelacanth Latimeria chalumnae: evolutionary implications

The living coelacanth Latimeria chalumnae is a relict species whose higher-level phylogenetic relationships have not been resolved clearly by traditional systematic approaches. Previous studies show that major differences in immunoglobulin gene structure and organization typify different phylogenetic lineages. To date, mammalian-, avian-, and elasmobranch-type gene organizations have been identified in representatives of these different phylads. A fourth form or organization is found in Latimeria, which possesses immunoglobulin heavy-chain variable region (VH) elements separated by approximately 190 nucleotides from diversity (D) elements. Adjacency of VH and D elements is characteristic of the elasmobranch "clustered" arrangement, although many other features of coelacanth VH gene organization and structure are more similar to those of bony fishes and tetrapods. These observations strongly support a phylogenetic hypothesis in which Latimeria occupies a sister-group relationship with teleosts and tetrapods.     

A mixed disulfide bond in bacterial glutathione transferase: functional and evolutionary implications

BACKGROUND: Glutathione S-transferases (GSTs) are a multifunctional group of enzymes, widely distributed in aerobic organisms, that have a critical role in the cellular detoxification process. Unlike their mammalian counterparts, bacterial GSTs often catalyze quite specific reactions, suggesting that their roles in bacteria might be different. The GST from Proteus mirabilis (PmGST B1-1) is known to bind certain antibiotics tightly and reduce the antimicrobial activity of beta-lactam drugs. Hence, bacterial GSTs may play a part in bacterial resistance towards antibiotics and are the subject of intense interest. RESULTS: Here we present the structure of a bacterial GST, PmGST B1-1, which has been determined from two different crystal forms. The enzyme adopts the canonical GST fold although it shares less than 20% sequence identity with GSTs from higher organisms. The most surprising aspect of the structure is the observation that the substrate, glutathione, is covalently bound to Cys 10 of the enzyme. In addition, the highly structurally conserved N-terminal domain is found to have an additional beta strand. CONCLUSIONS: The crystal structure of PmGST B1-1 has highlighted the importance of a cysteine residue in the catalytic cycle. Sequence analyses suggest that a number of other GSTs share this property, leading us to propose a new class of GSTs - the beta class. The data suggest that the in vivo role of the beta class GSTs could be as metabolic or redox enzymes rather than conjugating enzymes. Compelling evidence is presented that the theta class of GSTs evolved from an ancestral member of the thioredoxin superfamily.     

DQ-haplotype analysis in rhesus macaques: implications for the evolution of these genes

The DQA1 and DQB1 alleles of 258 rhesus monkeys (Macaca mulatta) of different origin were typed by PCR-RFLP. Five novel MamuDQA1 and five novel -DQB1 alleles were detected and 15 Mamu-DQA1-DQB1 haplotypes were identified. Haplotype analysis confirmed the conservation of the DQA1*01-DQB1 *06 haplotypes in evolution. The most conspicuous finding was the tight linkage between the Mamu-DQA1 and -DQB1 alleles. Almost in every case the Mamu-DQA1 allele was linked to only one particular Mamu-DQB1 allele. Although there also are constraints in the formation of DQ haplotypes in humans, such tight linkages are not observed. These findings support the hypothesis of some kind of co-evolution between DQA1 and DQB1 alleles and may reflect a stronger force of natural selection in macaques than in humans.     

Lactone-ring-cleaving enzyme: genetic analysis, novel RNA editing, and evolutionary implications

A lactonohydrolase from Fusarium oxysporum AKU 3702 is an enzyme catalyzing the hydrolysis of aldonate lactones to the corresponding aldonic acids. The amino acid sequences of the NH2 terminus and internal peptide fragments of the enzyme were determined to prepare synthetic oligonucleotides as primers for the PCR. An approximate 1, 000-base genomic DNA fragment thus amplified was used as the probe to clone both genomic DNA and cDNA for the enzyme. The lactonohydrolase genomic gene consists of six exons separated by five short introns. A novel type of RNA editing, in which lactonohydrolase mRNA included the insertion of guanosine and cytidine residues, was observed. The predicted amino acid sequence of the cloned lactonohydrolase cDNA showed significant similarity to those of the gluconolactonase from Zymomonas mobilis, and paraoxonases from human and rabbit, forming a unique superfamily consisting of C-O cleaving enzymes and P-O cleaving enzymes. Lactonohydrolase was expressed under the control of the lac promoter in Escherichia coli.     

Temporal filtering properties of ampullary electrosensory neurons in the torus semicircularis of Eigenmannia: evolutionary and computational implications

Weakly electric fish have parallel electrosensory systems, the phylogenetically older ampullary system and the novel tuberous system. The tuberous system is an adaptation related to the evolution of active electrolocation. To examine the evolutionary relationship of the ampullary and tuberous systems, the temporal filtering properties of ampullary neurons in the dorsal torus semicircularis of Eigenmannia were studied. 'Whole-cell' recordings were made in vivo using patch-type pipettes. The responses of 19 neurons to sinusoidal electric signals (< 40 Hz) were recorded and the anatomy of these neurons demonstrated by injection of biocytin. All eight low-pass ampullary neurons had broad, relatively smooth post-synaptic potentials (psps) that at low frequencies nicely reflected the sinusoidal stimuli. These neurons had somata of 10-14 microns diameter and thick, spiny dendrites. Eight high-pass neurons were recorded, representing three physiological classes. The first class (3 neurons) had psps that roughly followed the sinusoidal time course of the stimulus; the psp morphology was similar to low-pass neurons. The second class had many small, fast, individual psps; their rate of occurrence varied with the stimulus. Finally, four neurons showed psps that were of constant width across stimulus frequencies. All three classes of high-pass neurons had small somata (8-10 microns diameter) with thin dendrites and either few or no spines. Some of these neurons had large varicosities on the dendrites. Three neurons had band-pass filtering properties: neurons that showed strong band-pass properties were morphologically similar to low-pass neurons. Comparisons of the temporal filtering, shapes of post-synaptic potentials, and anatomy of ampullary and tuberous neurons in the torus suggest that the circuitry for tuberous processing in the torus may have evolved as an elaboration or duplication of the ampullary system. The mechanisms underlying the low-pass filtering characteristics of tuberous neurons therefore appear to have predated the evolution of the tuberous system and to have served as a pre-adaptation for the evolution of the jamming avoidance response. In addition, these data support the hypothesis that spine density influences the temporal filtering properties of neurons.     

Breast cancer metastasis-associated genes: prognostic significance and therapeutic implications

The metastatic spread of breast cancer accounts for most of its morbidity and mortality; therefore, identifying the genes and gene products involved in breast cancer metastasis formation should be useful for better diagnosis, prognosis, treatment, and follow-up of patients with metastatic breast cancer. Unfortunately, little is known about these genes or the functions of their encoded products. Abnormalities in at least three broad gene categories (oncogenes, regulatory genes or effector genes, and tumor-suppressor genes) have been shown to contribute to the origin and/or progression of breast neoplasias. Such abnormalities are mainly manifested by quantitative changes in gene expression, resulting in loss of normal cellular regulation and enhanced cellular diversification. In addition, qualitative genetic alterations, such as gene amplifications and mutations, may also be involved in breast cancer progression. The role(s) of different breast cancer metastasis-associated genes, if known, in the complex multistep process of invasion and metastasis is discussed along with studies that have identified new molecular probe(s) that may be useful in predicting metastasis formation and outcome in breast cancer and for selecting candidates for adjuvant therapy. Understanding the genetic and thus molecular basis of metastasis formation should also provide important insights on the development of new therapeutic approaches for treatment of metastatic breast cancers based on gene targeting and repair of genetic defects that control metastatic properties.     

Frequency of migrants and migratory activity are genetically correlated in a bird population: evolutionary implications

Most migratory bird populations are composed of individuals that migrate and individuals that remain resident. While the role of ecological factors in maintaining this behavioral dimorphism has received much attention, the importance of genetic constraints on the evolution of avian migration has not yet been considered. Drawing on the recorded migratory activities of 775 blackcaps (Sylvia atricapilla) from a partially migratory population in southern France, we tested two alternative genetic models about the relationship between incidence and amount of migratory activity. The amount of migratory activity could be the continuous variable "underlying" the phenotypic expression of migratory urge, or, alternatively, the expression of both traits could be controlled by two separate genetic systems. The distributions of migratory activities in five different cohorts and the inheritance pattern derived from selective breeding experiments both indicate that incidence and amount of migratory activity are two aspects of one trait. Thus, all birds without measurable activity have activity levels at the low end of a continuous distribution, below the limit of expression or detection. The phenotypic dichotomy "migrant-nonmigrant" is caused by a threshold which may not be fixed but influenced both genetically and environmentally. This finding has profound implications for the evolution of migration: the transition from migratoriness to residency should not only be driven by selection favoring resident birds but also by selection for lower migratory activity. This potential for selection on two aspects, residency and migration distance, of the same trait may enable extremely rapid evolutionary changes to occur in migratory behavior.     

The evolutionary scrambling and developmental unscrambling of germline genes in hypotrichous ciliates

Genes in the germline (micronuclear) genome of hypotrichous ciliates are interrupted by multiple, short, non-coding, AT-rich sequences called internal eliminated segments, or IESs. During conversion of a micronucleus to a somatic nucleus (macronucleus) after cell mating, all IESs are excised from the germline genes and the gene segments, called macronuclear-destined segments, or MDSs, are spliced. Excision of the approximately 150 000 IESs from a haploid germline genome in Oxytricha nova requires approximately 150 000 recombinant events. In three of 10 genes the MDSs are scrambled. During macronuclear development the MDSs are unscrambled, possibly by folding of the DNA to allow MDSs to ligate in the correct order. The nine MDSs in the actin I gene of O.nova are scrambled in the random order, 3-4-6-5-7-9-2-1-8, and MDS 2 is inverted. The 14 MDSs in the alphaTP gene of O.nova and Stylonychia mytilus are scrambled in the non-random order, 1-3-5-7-9-11-2-4-6-8-10-12-13-14. The 45 MDSs in the DNA pol alpha gene are non-randomly scrambled into an odd/even series, with an inversion of one-third of the gene. Additional IESs have been inserted into these three genes during evolution of Oxytricha trifallax, slightly modifying scrambling patterns. The non-random scrambled patterns in the alphaTP and DNA pol alpha genes are explained by multiple, simultaneous IES insertions. The randomly scrambled pattern in the actin I gene may arise from an initially non-randomly scrambled pattern by recombination among multiple IESs. Alternatively, IESs inserted sporadically (individually) in a non-scrambled configuration might subsequently recombine, converting a non-scrambled gene into a randomly scrambled one. IESs shift along a DNA molecule, most likely as a result of mutations at MDS/IES junctions. Shifting of IESs has the effect of 'transferring' nucleotides from one MDS to another, but does not change the overall sequence of nucleotides in the combined MDSs. In addition to shifting in position, IESs accumulate mutations at a high rate and increase and decrease in length within a species and during speciation. The phenomena of IESs and of MDS scrambling represent remarkable flexibility of the hypotrich genome, possibly reflecting a process of MDS shuffling that facilitates the evolution of genes.     

The MHC class I genes of the rhesus monkey. Different evolutionary histories of MHC class I and II genes in primates

Homologues of the human HLA-A and -B MHC class I loci have been found in great apes and Old World primates suggesting that these two loci have existed for at least 30 million years. The C locus, however, shows some sequence similarity to the B locus and has been found only in gorillas, chimpanzees, and humans. To determine the age of the MHC class I C locus and to examine the evolution of the A and B loci we have cloned, sequenced, and in vitro translated 16 MHC class I cDNAs from two unrelated rhesus monkeys (Macaca mulatta) using both cDNA library screening and PCR amplification. Analyses of these sequences suggest that the C locus is not present in the rhesus monkey, indicating that this locus may be of recent origin in gorillas, chimpanzees, and humans. The rhesus monkey's complement of MHC class I genes includes the products of at least one expressed A locus and at least two expressed B loci, indicating that a duplication of the B locus has taken place in the lineage leading to these Old World primates. Comparison of rhesus monkey MHC class I cDNAs to their primate counterparts reveals fundamental differences between MHC class I and class II evolution in primates. Although MHC class II allelic lineages are shared between humans and Old World primates, no such trans-species sharing of allelic lineages is seen at the MHC class I loci.     

Cognitive function in mammals: the evolutionary perspective

The work of behavioural pharmacologists has concentrated on small animals, such as rodents and pigeons. The validity of extrapolation of their findings to humans depends upon the existence of parallels in both physiology and psychology between these animals and humans. This paper considers the question whether there are in fact substantial cognitive parallels between, first, different non-human groups of vertebrates and, second, non-humans and humans. Behavioural data from 'simple' tasks, such as habituation and conditioning, do not point to species differences among vertebrates. Using examples that concentrate on the performance of rodents and birds, it is argued that, similarly, data from more complex tasks (learning-set formation, transitive inference, and spatial memory serve as examples) reveal few if any cognitive differences amongst non-human vertebrates. This conclusion supports the notion that association formation may be the critical problem-solving process available to non-human animals; associative mechanisms are assumed to have evolved to detect causal links between events, and would therefore be relevant in all ecological niches. In agreement with this view, recent advances in comparative neurology show striking parallels in functional organisation of mammalian and avian telencephalon. Finally, it is argued that although the peculiarly human capacity for language marks a large cognitive contrast between humans and non-humans, there is good evidence-in particular, from work on implicit learning--that the learning mechanisms available to non--humans are present and do play an important role in human cognition.     

Expression of acetylcholine receptor genes in human thymic epithelial cells: implications for myasthenia gravis

The intrathymic presence of the muscle acetylcholine receptor (AChR) is controversial, and the nature of the cell(s) expressing it is unclear. We thus analyzed the molecular expression of muscle AChR in human thymi. mRNA studies indicated that the two isoforms (P3A+ and P3A-) of the alpha-subunit were present in thymic extracts and in cultured thymic epithelial cells (TEC), while expression in thymocytes was low and not consistently detectable. The amount of mRNA coding for the alpha-subunit, evaluated by means of quantitative PCR, was about 20 times less in TEC than in muscle, and was similar in TEC from normal subjects and from patients with myasthenia gravis (MG). The beta- and epsilon-subunits present in adult AChR were also expressed in TEC (but not in thymocytes), while the embryonic subunit (gamma) was absent. In TEC cultures, the AChR alpha- and epsilon-subunit mRNA levels were down-regulated by forskolin, as also observed in the TE671 rhabdomyosarcoma cell line, suggesting similar regulation of AChR subunits in thymus and muscle. Protein expression was evidenced on TEC (but not on thymocytes), by Western blotting as well as by immunofluorescence, thus demonstrating AChR expression on human thymic epithelial cells. There was no difference in the expression of AChR between TEC from MG patients and controls, meaning that the expression of AChR subunits alone is not sufficient to explain the onset of MG.