Phylogenetic screening of the human genome: identification of differentially hybridizing repetitive sequence families

The phi-screen, a method of phylogenetic screening, can be employed to detect repetitive sequence families that differentially hybridize between closely related species. Such differences may involve sequence divergence or variations in copy number, including total presence versus absence of a family of repeated DNA. We present the results of a phi-screen comparing the human genome to that of the prosimian, Galago crassicaudatus. Three human repetitive families that are divergent or not present in galago have been detected. One of these families is described in detail; it is similar among the anthropoids but is present in a lower copy number and/or divergent form in prosimians. The family is clearly related to the transposon-like human element (THE) described by Paulson et al. (1985). THEs have long terminal repeats reminiscent of retroviruses but are unique in that they have no sequence similarity to known mammalian retroviruses. The sequence of a solo long terminal repeat, found unassociated with THE internal sequence, is presented. This family member, THE p2, is bordered by a 5-bp target-site repeat and is interrupted by the insertion of an Alu element. A solo THE element sequenced by Wiginton et al. (1986) contains an insertion of Alu at precisely the same position as does THE p2.      

DNA divergence in and around the alcohol dehydrogenase locus in five closely related species of Hawaiian Drosophila

The alcohol dehydrogenase (Adh) region from five planitibia subgroup species of Hawaiian picture-wing Drosophila has been cloned. A total of 15 kb of DNA in and around the Adh gene has been compared among the five species. Genetic distances were calculated to determine evolutionary relationships. These distances agree with previous distances determined by protein polymorphism and DNA hybridization techniques and can be interpreted in terms of specific island colonization and speciation (founder) events over the past 5 Myr. Examination of the restriction maps of the cloned Adh region from the five species shows many instances of small deletions, insertion of a transposable element in D. heteroneura, and the existence of a highly variable region on the 3' side of the Adh gene. Clustering relationships and rates of DNA change are calculated and compared with the relationship found for other species of Drosophila.      

Toad radiation reveals into-India dispersal as a source of endemism in the Western Ghats-Sri Lanka biodiversity hotspot

Background  

High taxonomic level endemism in the Western Ghats-Sri Lanka biodiversity hotspot has been typically attributed to the subcontinent's geological history of long-term isolation. Subsequent out of – and into India dispersal of species after accretion to the Eurasian mainland is therefore often seen as a biogeographic factor that 'diluted' the composition of previously isolated Indian biota. However, few molecular studies have focussed on into-India dispersal as a possible source of endemism on the subcontinent. Using c. 6000 base pairs of mitochondrial and nuclear DNA, we investigated the evolutionary history and biogeography of true toads (Bufonidae), a group that colonized the Indian Subcontinent after the Indo-Asia collision.     

Prenatal genetic counseling for hemoglobinopathy carriers: a comparison of primary providers of prenatal care and professional genetic counselors.

Health personnel trained in medical genetics are insufficient to meet the demand for genetic services. Methods must be found to enable primary care providers to offer commonly needed genetic services themselves. In our recently reported community-wide prenatal screening program for hemoglobinopathies, 36% of women detected to have a hemoglobinopathy did not come to a tertiary center for counseling and thus may have not benefited from testing. To determine whether the efficiency of the program could be increased if counseling were provided by the prenatal care provider (obstetrician or family practitioner), we developed a pilot training program on the basis of our experience in offering such services and enlisted 68% of regional prenatal care providers to participate. The proportion of patients detected to have a hemoglobinopathy who received counseling was similar in the primary and tertiary provider groups: 59% versus 50%, respectively, for sickle trait, and 69% versus 66%, respectively, for beta-thalassemia trait. Knowledge after counseling was also similar for the primary and tertiary provider groups: 64% versus 66% (mean % correct), respectively, for sickle trait, and 79% versus 78%, respectively, for beta-thalassemia trait. However, the two provider groups significantly differed with regard to whether or not the patient had her partner tested. For sickle trait, it was 25% for the primary providers but 49% for the tertiary providers (P < .001). For beta-thalassemia trait, it was 47% for the primary providers but 78% for the tertiary providers (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)     

A Prototype Recombinant-Protein Based Chlamydia pecorum Vaccine Results in Reduced Chlamydial Burden and Less Clinical Disease in Free-Ranging Koalas (Phascolarctos cinereus)

Diseases associated with Chlamydia pecorum infection are a major cause of decline in koala populations in Australia. While koalas in care can generally be treated, a vaccine is considered the only option to effectively reduce the threat of infection and disease at the population level. In the current study, we vaccinated 30 free-ranging koalas with a prototype Chlamydia pecorum vaccine consisting of a recombinant chlamydial MOMP adjuvanted with an immune stimulating complex. An additional cohort of 30 animals did not receive any vaccine and acted as comparison controls. Animals accepted into this study were either uninfected (Chlamydia PCR negative) at time of initial vaccination, or infected (C. pecorum positive) at either urogenital (UGT) and/or ocular sites (Oc), but with no clinical signs of chlamydial disease. All koalas were vaccinated / sampled and then re-released into their natural habitat before re-capturing and re-sampling at 6 and 12 months. All vaccinated koalas produced a strong immune response to the vaccine, as indicated by high titres of specific plasma antibodies. The incidence of new infections in vaccinated koalas over the 12-month period post-vaccination was slightly less than koalas in the control group, however, this was not statistically significant. Importantly though, the vaccine was able to significantly reduce the infectious load in animals that were Chlamydia positive at the time of vaccination. This effect was evident at both the Oc and UGT sites and was stronger at 6 months than at 12 months post-vaccination. Finally, the vaccine was also able to reduce the number of animals that progressed to disease during the 12-month period. While the sample sizes were small (statistically speaking), results were nonetheless striking. This study highlights the potential for successful development of a Chlamydia vaccine for koalas in a wild setting.     

Circumvention of the methotrexate transport system by methotrexate-phosphatidylethanolamine derivatives: effect of fatty acid chain length

Methotrexate has been conjugated (amide bond) via either the alpha or gamma, or both alpha and gamma, glutamyl carboxyl groups to the amino function of dihexanoylphosphatidylethanolamine (C6C6PE) and 1-tetradecanoyl-2-hexanoylphosphatidylethanolamine (C14C6PE). These phospholipid prodrugs (either free or incorporated into liposomes) were compared with the corresponding ditetradecanoylphosphatidylethanolamine (C14C14PE) conjugates, some of whose properties have been described previously, for their ability to inhibit the proliferation of human leukemic cells (CEM/O) or cells derived therefrom (CEM/MTX) that are resistant to methotrexate because of a defective drug transport system. Regardless of chain length, the gamma conjugates were more effective than either the alpha or the alpha, gamma conjugates, in inhibiting growth of the parent cells, confirming initial experiments with mouse cells. Chain length had, however, a pronounced influence on the capacity of the various gamma derivatives to circumvent the transport defect. For example, CEM/MTX cells were 120-fold less susceptible than CEM/O cells to inhibition by either methotrexate or methotrexate-gamma-C6C6PE, whereas both cell lines were equally sensitive to methotrexate-gamma-C14C14PE. Although less potent than either of the foregoing, methotrexate-gamma-C14C6PE could partially by-pass the defective transport system. These results suggest that methotrexate-gamma-PE derivatives with appropriate acyl residues might be useful probes to investigate the mechanism by which phospholipids in general are able to traverse cell membranes.     

Germ band retraction as a landmark in glucose metabolism during <Emphasis Type="Italic">Aedes aegypti</Emphasis> embryogenesis

Background  

The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown.     

大鼠心肌缺血再灌注损伤模型的实验研究

目的 制备一种新型的心肌急性缺血再灌注损伤模型,以探讨一种更符合临床实际需求的实验方法.方法 将20只雌性SD(Sprague-Dawley)大鼠随机分成2组(对照组、实验组),采用结扎主动脉根部引起心肌缺血5min再灌注30 min建立心肌急性缺血再灌注模型;通过应用透射电镜观察心肌细胞超微结构的改变,同时检测心肌组织匀浆丙二醛(Maleic Dialdehyde,MDA)含量、超氧化物歧化酶(Superoxide Dismutase,SOD)活力.结果 透射电镜下超微结构显示实验组较对照组明显加重了心肌组织结构和线粒体的损害;实验组心肌组织MDA明显高于对照组(P<0.01),而SOD明显低于对照组(P<0.01).结论 本实验成功建立了方法简便、易于操作、取材范围广泛的心肌缺血再灌注损伤模型,为心肌缺血再灌注损伤研究提供了一种更为可行的模型.     

A molecular phylogeny of ichthyophiid caecilians (Amphibia: Gymnophiona: Ichthyophiidae): out of India or out of South East Asia?

Recent molecular phylogenetic studies indicate that the rafting Indian plate harboured several isolated vertebrate lineages between ca. 130 and 56 Myr ago that dispersed and diversified 'out of India' following accretion with Eurasia. A single family of the amphibian order Gymnophiona, the Ichthyophiidae, presently occurs on the Indian plate and across much of South East Asia. Ichthyophiid phylogeny is investigated in order to test competing out of India and out of South East Asia hypotheses for their distribution. Partial sequences of mitochondrial 12S and 16S rRNA and cytochrome b genes for 20 ichthyophiids and proximate outgroups were assembled. Parsimony, maximum-likelihood and distance analyses all recover optimum trees in which uraeotyphlids plus Ichthyophis cf. malabarensis are the sister taxa to all other Ichthyophis, among which the South East Asian taxa are monophyletic. Tree topology and branch lengths indicate that the Indian lineages are more basal and older, and thus are more consistent with the hypothesis that ichthyophiids dispersed from the Indian subcontinent into South East Asia. The estimated relationships also support monophyly of Sri Lankan Ichthyophis, and non-monophyly of striped and unstriped Ichthyophis species groups. Mitochondrial DNA sequences provide evidence that should assist current problematic areas of caecilian taxonomy.