Mitochondrial DNA geneflow indicates preferred usage of the Levant Corridor over the Horn of Africa passageway

Both the Levantine Corridor and the Horn of Africa route have figured prominently in early hominid migrations from Africa to Eurasia. To gauge the importance of these two African-Asian thoroughfares in the demic movements of modern man, we surveyed the mtDNA control region variation and coding polymorphisms of 739 individuals representing ten African and Middle Eastern populations. Two of these collections, Egypt and Yemen, are geographically close to the Levant and Horn of Africa, respectively. In this analysis, we uncover genetic evidence for the preferential use of the Levantine Corridor in the Upper Paleolithic to Neolithic dispersals of haplogroups H, J*, N1b, and T1, in contrast to an overwhelming preference in favor of the Horn of Africa for the intercontinental expansion of M1 during the Middle to Upper Paleolithic. Furthermore, we also observed a higher frequency of sub-Saharan mtDNA compared to NRY lineages in the Middle Eastern collections, a pattern also seen in previous studies. In short, the results of this study suggest that several migratory episodes of maternal lineages occurred across the African-Asian corridors since the first African exodus of modern Homo sapiens sapiens.

Polymorphic Alu insertions among Mayan populations

The Mayan homeland within Mesoamerica spans five countries: Belize, El Salvador, Guatemala, Honduras and Mexico. There are indications that the people we call the Maya migrated from the north to the highlands of Guatemala as early as 4000 B.C. Their existence was village-based and agricultural. The culture of these Preclassic Mayans owes much to the earlier Olmec civilization, which flourished in the southern portion of North America. In this study, four different Mayan groups were examined to assess their genetic variability. Ten polymorphic Alu insertion (PAI) loci were employed to ascertain the genetic affinities among these Mayan groups. North American, African, European and Asian populations were also examined as reference populations. Our results suggest that the Mayan groups examined in this study are not genetically homogeneous.

Translocation t(1;10) (q21;q26) in a case of acute nonlymphocytic leukemia

Chromosome banding studies carried out on bone marrow cells from a 16 year-old boy with an M1 acute nonlymphocytic leukemia (ANLL) revealed an unbalanced translocation involving chromosomes 1 and 10: der(10) t(1;10) (q21;q26) that results in a partial trisomy 1q between bands 1q21-1qter. Marker del(6)(q21) and trisomies of chromosomes 18, 21 and 22 were also observed. To our knowledge, this der(10) is the first to be reported in a patient with ANLL.

The relation between protein malnutrition, ethanol consumption and chromosomal damage induced by cyclophosphamide in bone marrow cells of mice

The effect of protein malnutrition and alcohol consumption on the yield of chromosomal damage induced by cyclophosphamide (CP) was studied. Chromosomal damage induced in bone marrow cells of BALB/c mice was established by scoring the frequency of dicentric chromosomes in C-banded slides. Results obtained showed that CP induced a significant increase of chromosomal damage in comparison with untreated mice. In addition, the yield of dicentric chromosomes was higher in mice fed with the hypoproteic diet. The animals which received ethanol in drinking water before treatment with CP exhibited the highest frequency of dicentric chromosomes, with no relation with the diet. Statistical analysis of these results showed the additive effect of diet and CP and are explained taking into account the metabolic pathways of CP as well as the decrease of enzymatic levels and the physiological condition in under-nourished mice.

The effect of a hypoproteic diet and ethanol consumption on the yield of chromosomal damage detected in bone marrow cells of mice

The relationship between protein malnutrition and ethanol consumption as modulating factors of the genetic response to xenobiotics was studied. BALB/c mice of both sexes were fed for three weeks after weaning either with a normal diet containing 25% protein or a hypoproteic diet containing 5% protein. Half of the animals received 20% ethanol in drinking water. Cytogenetic analysis was performed in bone marrow cells. Slides were stained for C-banding in order to assure the accurate scoring of dicentric chromosomes. Results obtained showed an increased frequency of dicentric chromosomes in mice fed with the hypoproteic diet (5.45 dicentrics per 100 cells) in contrast to mice fed with the normal diet (0.61 dicentrics per 100 cells). Ethanol consumption increased the frequency of chromosomal damage, but no differences in the effect of ethanol between mice fed with the normal diet and mice fed with the hypoproteic diet (16.33 and 16.80 dicentrics per 100 cells respectively). The enhanced frequency of dicentric chromosomes in animals fed with the hypoproteic diet might have been originated from the increase or the improper repair of chromosome breaks. The similarity in the response to ethanol consumption in animals fed either with the normal or the hypoproteic diet might have been provoked by a decrease of alcohol dehydrogenase (ADH) level in undernourished mice. The chromosomal damage due to ethanol may be lower in undernourished mice than in mice fed with the normal diet due to the reduced amount of circulating acetaldehyde able to induce chromosomal damage. The results obtained are an evidence of the role played by the diet in the modulation of the genetic response to xenobiotics.

The induction of aneuploidy in cultured Chinese hamster cells by propionaldehyde and chloral hydrate

The induction of aneuploidy in cultured Chinese hamster cells by propionaldehyde (PA) and chloral hydrate (CH) has been studied. Chinese hamster embryonic diploid (CHED) cells were grown as a monolayer in cover glasses. Treatments were performed with doses of 5 x 10(-4), 1 x 10(-3) and 2 x 10(-3)% of PA for 3 h and doses of 1 x 10(-3), 2 x 10(-3) and 3 x 10(-3)% of CH for 1.5 h. Treatments with 2 x 10(-3)% of acetaldehyde (AA) for the same PA and CH treatments were used as positive controls. Untreated cultures were used as negative controls. PA induced chromosomal aberrations with the three doses employed although in a lesser degree than the positive control. CH induced chromosomal damage only with the two higher doses. No correlation was found between the amount of chromosomal damage induced and the doses of PA or CH employed. Both compounds increased the frequency of aneuploid cells in relation to untreated controls but not in relation to the positive control. However, neither PA nor CH significantly increased the frequencies of polyploid cells. These results indicate that aldehydes and chlorine-replaced aldehydes are strong inducers of aneuploidy despite some differences between PA or CH and AA regarding cytotoxicity and polyploidy induction.

Variations of rat skull bone robusticity evoked by malnutrition

Weanling Holtzman rats of both sexes were fed a control (25% protein), a 10% protein, and a 2% protein semisynthetic diet. Protein deficit (PD) and protein calorie malnutrition (PCM) were estimated from comparisons between control and 10% protein, and control and 2% protein-fed animals, respectively. Animals were killed when they were 56 days old and their skulls cleaned and disarticulated. Individual bones and incisors were ovendried to constant weight. Total weight (TW), maximal projected length (MPL), and robusticity index (RI) were determined on each bone and incisor. It was found that all the bones and incisors did not behave uniformly. They followed two main patterns: (1) Proportional variation. RI values were not affected by nutritional deficiencies. All basicranial bones and 4 of 10 facial bones followed this pattern. (2) Non-proportional variation. RI values were affected by nutritional deficiencies. This pattern was subdivided into two trends: (2a) PD-diminished RI values. Both upper and lower incisors and 1 of 10 facial bones followed this trend. (2b) PCM, but not PD, decreased RI values. All vault bones and the remaining five facial bones followed this trend. It was concluded that there was a differential robusticity response among cranial base, calvaria, and incisors. This response may be connected with the differences in both histogenetic characteristics of those components and the functional roles they have to perform. The nonvault intramembranous bones showed a nonspecific behavior. This fact precluded the classification of the facial region in some of the previously defined patterns.