The Vacuum Cherenkov Detector (VCD) for γ-ray measurements in inertial confinement fusion experiments

Inertial confinement fusion experiments at both the National Ignition Facility (NIF) and the Laboratory for Laser Energetics OMEGA laser facility currently utilize Cherenkov detectors, with fused silica as the Cherenkov medium. At the NIF, the Quartz Cherenkov Detectors improve the precision of neutron time-of-flight measurements; and at OMEGA, the Diagnostic for Areal Density provides measurements of capsule shell areal densities. An inherent property of fused silica is the radiator's relatively low energy threshold for Cherenkov photon production (E_threshold < 1 MeV), making it advantageous over gas-based Cherenkov detectors for experiments requiring low-energy γ detection. The Vacuum Cherenkov Detector (VCD) has been specifically designed for efficient detection of low energy γ's. Its primary use is in implosion experiments, which will study reactions relevant to stellar and big-bang nucleosynthesis, such as T(⁴He,γ)⁷Li, ⁴He(³He,γ)⁷Be, and ¹²C(p,γ)¹³N. The VCD is compatible with LLE's standard Ten-Inch Manipulator diagnostic insertion module. This work will outline the design and characterization of the VCD as well as provide results from recent experiments conducted at the OMEGA laser facility.

Upgrade of the gated laser entrance hole imager G-LEH-2 on the National Ignition Facility

A major upgrade has been implemented for the ns-gated laser entrance hole imager on the National Ignition Facility (NIF) to obtain high-quality data for Hohlraum physics study. In this upgrade, the single "Furi" hCMOS sensor (1024 × 448 pixel arrays with two-frame capability) is replaced with dual "Icarus" sensors (1024 × 512 pixel arrays with four-frame capability). Both types of sensors were developed by Sandia National Laboratories for high energy density physics experiments. With the new Icarus sensors, the new diagnostic provides twice the detection area with improved uniformity, wider temporal coverage, flexible timing setup, and greater sensitivity to soft x rays (<2 keV). These features, together with the fact that the diagnostic is radiation hardened and can be operated on the NIF for high neutron yield deuterium-triterium experiments, enable significantly greater return of data per experiment.

Perspectives on the clonal persistence of presumed 'ghost' genomes in unisexual or allopolyploid taxa arising via hybridization

Although hybridization between non-sibling species rarely results in viable or fertile offspring, it occasionally produces self-perpetuating or sexually-parasitic lineages in which ancestral genomes are inherited clonally and thus may persist as ‘ghost species’ after ancestor extinction. Ghost species have been detected in animals and plants, for polyploid and diploid organisms, and across clonal, semi-clonal, and even sexual reproductive modes. Here we use a detailed investigation of the evolutionary and taxonomic status of a newly-discovered, putative ghost lineage (HX) in the fish genus Hypseleotris to provide perspectives on several important issues not previously explored by other studies on ghost species, but relevant to ongoing discussions about their detection, conservation, and artificial re-creation. Our comprehensive genetic (allozymes, mtDNA) and genomic (SNPs) datasets successfully identified a threatened sexual population of HX in one tiny portion of the extensive distribution displayed by two hemi-clonal HX-containing lineages. We also discuss what confidence should be placed on any assertion that an ancestral species is actually extinct, and how to assess whether any putative sexual ancestor represents a pure remnant, as shown here, or a naturally-occurring resurrection via the crossing of compatible clones or hemi-clones.

Weight loss and improved metabolic outcomes amongst rural African American women in the Deep South: six-month outcomes from a community-based randomized trial

BACKGROUND

Obesity is highly prevalent in African American women, especially those in the rural southern USA, resulting in persistent health disparities.

OBJECTIVE

To test the effectiveness of an evidence-based behavioural weight loss intervention delivered by community health advisors to African American women in the rural south.

DESIGN AND METHODS

Overweight or obese African American women (30-70 years) from eight counties in Mississippi and Alabama participated in a 24-month randomized controlled trial of an evidence-based behavioural weight loss programme augmented with community strategies to support healthy lifestyles (Weight Loss Plus, N = 154) compared to the weight loss programme alone (Weight Loss Only, N = 255). This study reports on 6-month outcomes on primary (weight change) and secondary (waist circumference, blood pressure, lipids, fasting blood glucose) outcomes, coinciding with the completion of the intensive weight loss phase.

RESULTS

Weight Loss Only participants lost an average of 2.2 kg (P < 0.001). Weight Loss Plus participants lost an average of 3.2 kg (P < 0.001). The proportion of the total sample that lost at least 5% of their body weight was 27.1% with no difference between treatment groups. Similarly, we observed statistically significant reductions in blood pressure, waist circumference and triglycerides in each treatment group, with no statistical differences between groups.

CONCLUSION

Trained lay health staff and volunteers from the rural southern USA were able to deliver a translation of a high-intensity behavioural intervention targeted to African American women, resulting in clinically meaningful weight loss and improvement in other metabolic outcomes in a significant proportion of participants.

Observation of hohlraum-wall motion with spectrally selective x-ray imaging at the National Ignition Facility

The high fuel capsule compression required for indirect drive inertial confinement fusion requires careful control of the X-ray drive symmetry throughout the laser pulse. When the outer cone beams strike the hohlraum wall, the plasma ablated off the hohlraum wall expands into the hohlraum and can alter both the outer and inner cone beam propagations and hence the X-ray drive symmetry especially at the final stage of the drive pulse. To quantitatively understand the wall motion, we developed a new experimental technique which visualizes the expansion and stagnation of the hohlraum wall plasma. Details of the experiment and the technique of spectrally selective x-ray imaging are discussed.

The complete mitochondrial DNA genome of Aedes vigilax (Diptera: Culicidae)

The complete mitochondrial genomes of two main clades of the medically significant saltmarsh mosquito Aedes vigilax Skuse (Diptera: Culicidae) were obtained using combined Illumina and Sanger sequencing. The two 15,877 bp circular genomes share 99.0% nucleotide identity and encode 37 genes with identical gene arrangement similar to previously published Culicidae species with a non-coding A + T rich region between rns and tRNA-Ile. Protein initiation codon is ATN apart from ND5 (GTG) and COX1 (TCG). Eight protein-coding genes encode full TAA stop codon, while five are completed by mRNA polyadenylation. Typical cloverleaf structures containing DHU and TΨC stem and loops can be inferred for all 22 tRNAs.

The complete mitochondrial DNA genomes for two lineages of Aedes notoscriptus (Diptera: Culicidae)

The complete mitochondrial genomes for two deeply divergent lineages of the urban adapted mosquito Aedes notoscriptus Skuse (Diptera: Culicidae) in Australia were sequenced using a combination of next generation Illumina and traditional Sanger sequencing. The 15,846 and 15,851 bp circular genomes share 95.0% nucleotide identity. They both have the full complement of 37 metazoan genes and identical gene arrangements to previously published Culicidae species with the one non-coding A + T rich control region present between rns and tRNA-Ile. All protein initiation codons are ATN apart from COX1 (TCG). Eight protein coding genes encode full TAA stop codons, one uses an incomplete TA and four use T. Typical cloverleaf structures containing DHU and TΨC stem and loops can be inferred for all 22 tRNAs.

Vaccines for immunological control of fertility in animals

Fertility control has gained considerable momentum as a management tool to regulate populations of captive and wild animals and to control aggressive behaviour or improve meat quality in livestock. Anti-fertility vaccination (immunocontraception and immunocastration) is a humane alternative to methods that rely on surgical or chemical sterilisation and lethal control. Two types of experimental immunocontraceptive vaccine have been registered for field use in animals. They contain either porcine zona pellucida (PZP) proteins extracted from pig ovaries or synthetic conjugated gonadotrophin releasing hormone (GnRH) peptides. These vaccines require repeated injections and are limited to captive or small populations of free-ranging wild animals. Alternative immunocontraceptive vaccines are actively being developed either to improve efficacy or enable large numbers of wild animals to be targeted. Some employ live genetically modified viruses to deliver immunocontraception and have proved successful under laboratory conditions. The relative merits, risks, social acceptability and regulations controlling the use of existing and novel animal immunocontraceptives are reviewed.

A virus vector based on Canine Herpesvirus for vaccine applications in canids

Canine Herpesvirus (CHV) is being developed as a virus vector for the vaccination of European red foxes. However, initial studies using recombinant CHV vaccines in foxes revealed viral attenuation and lack of antibody response to inserted foreign antigens. These findings were attributed both to inactivation of the thymidine kinase (TK) gene and excess foreign genetic material in the recombinant viral genome. In this study, we report an improved CHV-bacterial artificial chromosome (BAC) vector system designed to overcome attenuation in foxes. A non-essential region was identified in the CHV genome as an alternative insertion site for foreign genes. Replacement of a guanine/cytosine (GC)-rich intergenic region between UL21 and UL22 of CHV with a marker gene did not change growth behaviour in vitro, showing that this region is not essential for virus growth in cell culture. We subsequently produced a CHV-BAC vector with an intact TK gene in which the bacterial genes and the antigen expression cassette were inserted into this GC-rich locus. Unlike earlier constructs, the new CHV-BAC allowed self-excision of the bacterial genes via homologous recombination after transfection of BACs into cell culture. The BAC-CHV system was used to produce a recombinant virus that constitutively expressed porcine zona pellucida subunit C protein between the UL21 and UL22 genes of CHV. Complete self-excision of the bacterial genes from CHV was achieved within one round of replication whilst retaining antigen gene expression.

Prospects for immunocontraception in the European red fox (Vulpes vulpes)

The European red fox is an introduced pest species in Australia for which improved means of control are urgently needed. Research efforts have focussed recently on the development of novel biological control methods to reduce the serious impact this species continues to have on both native fauna and the sheep industry. The ultimate goal has been to generate an antifertility vaccine for use on foxes that relies on a process termed ‘immunocontraception’. A variety of proteins derived from sperm and oocytes, together with different delivery vectors, have been experimentally assessed for their ability to induce immunocontraceptive responses in foxes. Vaccine vectors screened have included Salmonella typhimurium, vaccinia virus and canine herpesvirus but suppression of fertility has yet to be achieved with any combination of antigen and delivery vector. Downregulation of fox mucosal antibodies during oestrus, lack of vector replication and low antibody responses to the target antigens have been the main constraints in successful fertility control. The fox is not well known as an experimental animal and the logistics of dealing with this difficult-to-handle species proved to be a major challenge when compared with other species, such as rabbits and mice. Despite these difficulties, research on fox immunocontraception has generated important insights into the reproductive biology, husbandry, biology and basic immunology of viral vectors in European red foxes. This information represents a valuable knowledge base should antifertility vaccination for foxes be revisited in the future.

Biological control of vertebrate pests using virally vectored immunocontraception

Species-specific viruses are being genetically engineered to produce contraceptive biological controls for pest animals such as mice, rabbits and foxes. The virus vaccines are intended to trigger an autoimmune response in the target animals that interferes with their fertility in a process termed virally vectored immunocontraception. Laboratory experiments have shown that high levels of infertility can be induced in mice infected with recombinant murine cytomegalovirus and ectromelia virus expressing reproductive antigens as well as in rabbits using myxoma virus vectors. The strategies used to produce and deliver species-specific immunocontraceptive vaccines to free-living wildlife are presented in this review. Discussion includes coverage of the likely safety of the proposed vaccines as well as the implications of the approach for fertility control in other species.

Dispersal and phylogeography of the agamid lizard Amphibolurus nobbi in fragmented and continuous habitat

Approximately 90% of native vegetation has been cleared for agriculture in central New South Wales, Australia. Habitat loss has reduced and fragmented populations of the agamid lizard Amphibolurus nobbi. We compared genetic structure of populations of this species in an unmodified landscape with those from small nature reserves and linear remnants in farming areas. We ask: Is there evidence for reduced dispersal and population fragmentation among farm populations? Using 2008 bp mtDNA sequences and allozyme electrophoresis, we found that small populations in farming areas had as much genetic variation as populations in nature reserves. Application of nested clade analysis (NCA) indicated isolation-by-distance effects among populations from uncleared areas, but not among populations within farming locations. The genetic evidence therefore implied a high level of migration in the cleared landscapes. High dispersal after fragmentation may have resulted from either a burst of movement at the time of land clearing with dragons from many sources finding refuge in a few remnants, or from ongoing rapid dispersal through unsuitable habitat. A phylogeny based on mtDNA revealed that A. nobbi populations in the study area are deeply divided into two reciprocally monophyletic groups. Although we did not sample the entire species range, one of these evolutionarily significant units was only detected in remnant vegetation in the agricultural landscape. Therefore, a substantial subclade of this species may be vulnerable to extinction. Our findings emphasize that local populations of widespread species can harbour important intraspecific genetic diversity, supporting the case for maintaining widespread species throughout production landscapes.

Assessment of the immunocontraceptive effect of a zona pellucida 3 peptide antigen in wild mice

Immunizing laboratory mice against a short peptide to mouse zona pellucida protein 3 (mZP3; amino acids 328-342) reduces fertility in some strains. This antigen was therefore tested to see if it is suitable for use in an immunocontraceptive vaccine to control wild mice. Mouse zona pellucida protein 3 peptide conjugated to a carrier protein (keyhole limpet hemocyanin) was considerably more immunogenic and effective in reducing fertility in wild mice when compared with inbred BALB/c mice. Fertility of the immunized wild mice was reduced by over 50% compared with controls, whereas BALB/c mice showed no reduction. Variation in the responses between individual animals to mZP3 peptide was observed and infertility correlated to the presence of cross-reacting antibodies to native zona pellucida in wild, but not BALB/c, mice.

Contraceptive responses of mice immunized with purified recombinant mouse zona pellucida subunit 3 (mZP3) proteins

Mouse zona pellucida subunit 3 (mZP3) was tested for efficacy as an immunocontraceptive antigen by comparing the fertility of mice immunized with recombinant mZP3 proteins. Recombinant protein was expressed using either the vaccinia virus T7 mammalian (vmZP3 protein) or baculovirus insect cell (bmZP3 protein)-expression systems. Female BALB/c or wild mice were immunized by i.p. injection using Freund's complete adjuvant and boosted three times with affinity purified recombinant proteins in Freund's incomplete adjuvant. Most mice developed antibodies that crossreacted to the respective mZP3 antigens by ELISA or western blot. In BALB/c mice immunized with vmZP3, fertility and mean litter size were reduced transiently to 25% and 10%, respectively, of those of control mice. However, immunization with bmZP3 did not affect either the fertility or mean litter sizes in BALB/c or wild mice immunized with bmZP3. The results demonstrate that reduction in fertility can be achieved in female BALB/c mice immunized using Freund's adjuvants and recombinant mZP3 protein produced in a mammalian, but not an insect, cell-expression system. Arguments are presented for the likely role of glycosylation of the mZP3 antigen in inducing contraceptive immune responses.

Mouse-specific immunocontraceptive polyepitope vaccines

Two mouse-specific polyepitope protein antigens comprising different combinations of sequences chosen from the mouse fertility antigens zona pellucida proteins 1 and 3 (ZP1 and ZP3), prolactin, proliferin, granulocyte-macrophage colony-stimulating factor (GM-CSF), sperm protein SP56 and T-helper cell-stimulating epitopes were produced in bacterial protein expression systems. The recombinant proteins were fused to maltose binding protein (MBP) and used to immunize female mice; their effects on fertility were assessed. Controls were immunized with either MBP only or phosphate buffered saline (PBS). One antigen construct (MBP-polyepitope B), containing mouse-specific epitopes for ZP1, ZP3, SP56 and proliferin, significantly reduced the fertility of female BALB/c mice. Fertility in this group was decreased by > 40% compared with the MBP control and the number of viable embryos was decreased by > 60%. This construct will now be used to produce the antigen in a recombinant murine cytomegalovirus for assessment as a potential mouse-specific anti-fertility vaccine for use in the control of mice in the field.

The complete cDNA sequences of IL-2, IL-4, IL-6 AND IL-10 from the European rabbit (Oryctolagus cuniculus)

The cDNAs for four rabbit cytokine genes [interleukin 2 (IL-2), IL-4, IL-6 and IL-10] have been cloned from primary lymphocytes by polymerase chain reaction (PCR) methods. IL-2 and IL-10 are both highly conserved between rabbit and other species. IL-4 and IL-6 are less strongly conserved, at both nucleotide and amino acid levels, and exhibit structural differences. An extension of the coding region of rabbit IL-6 relative to all other reported IL-6 genes results from a mutation in the usual stop codon which allows translation to continue for a further 27 amino acids. Analysis of IL-6 from four other lagomorph species suggests that this mutation is specific to the European rabbit. Sequence and structural differences of IL-4 and IL-6, while presumably not altering function, may render them highly species-specific. Several alternatively spliced variants of IL-2 and IL-4 are also reported.

Expression of recombinant mouse sperm protein sp56 and assessment of its potential for use as an antigen in an immunocontraceptive vaccine

Recombinant mouse sp56 protein was produced for testing as an antigen in an immunocontraceptive vaccine. The coding sequence for the mature sp56 protein was cloned into the bacterial expression system pFLAG using a PCR-based method on mouse testis cDNA. Polyclonal antisera were raised in mice against affinity purified recombinant sp56 fusion protein (sp56FLAG) or an artificial sp56 peptide fused to a carrier protein (KLH) and shown to cross-react to a protein band of 75 kD in detergent extracts of mouse sperm by Western immunoblot analysis under reducing conditions. The antisera to sp56FLAG also immunolocalized over the entire acrosome of mouse sperm. Female BALB/c mice were immunized intraperitoneally with sp56FLAG in a fertility trial with 20 microg sp56FLAG in Freund's Complete Adjuvant and boosted three to five times with 20 microg sp56FLAG in Freund's Incomplete Adjuvant. Litter sizes of sp56FLAG-treated mice were significantly smaller than control-treated animals after five boosts.

Characterisation of two highly conserved but non-allelic cellular disintegrins from rabbit testis

Two novel cellular disintegrin genes (termed ADAM 6d and ADAM 6e: Gen Bank accession numbers U82750 and U82751) were isolated and characterised from a rabbit testicular cDNA library. The cDNAs have open reading frames encoding for proteins of 731 and 730 amino acids, respectively. They share an amino-acid homology of greater than 89% and a nucleotide base matching of 94% in both the coding and non-coding regions. PCR of DNA extracted from both the parents and progeny of wild rabbits was used to demonstrate that the genes are non-allelic. Recombinant ADAM 6e fused to maltose binding protein was prepared and polyclonal antibodies produced in mice. These polyclonal antibodies recognised two bands with molecular masses of 42 kDa and 46 kDa on Western blots of rabbit sperm extracts run on SDS PAGE reducing gels. The implications of the presence of these two highly conserved proteins in rabbit testis and on sperm are discussed.

Examination of the immunocontraceptive potential of recombinant rabbit fertilin subunits in rabbit

Recombinant fertilin subunits produced in a bacterial expression systems were used to test fertilin as an immunocontraceptive antigen in the European rabbit (Oryctolagus cuniculus). Wild female rabbits (n = 40) were immunized with either recombinant rabbit fertilin alpha or beta subunits by the s.c. or intra-Peyer's patch route. High titers of serum anti-fertilin polyclonal IgG antibodies were achieved in all rabbits after repeated boosts, with fertilin-specific IgG but not IgA antibodies detected in vaginal lavages of all animals. The serum IgG antibodies recognized polypeptides in detergent extracts of rabbit sperm with relative molecular masses of 48, 53, and 85 kDa on reducing SDS-PAGE gels and were shown to bind to the head region of methanol-fixed and live caudal rabbit sperm. Preincubation of rabbit sperm with these anti-fertilin IgG antibodies at concentrations of 400 micrograms/ml blocked sperm binding to zona-intact oocytes and inhibited fertilization in vitro by 60-80%. However, despite the levels of circulating and vaginal IgG antibodies achieved, only 4 immunized does failed to become pregnant out of 33 that ovulated. The remaining animals either showed no effect on fertility (n = 29) relative to control animals or failed to ovulate (n = 7). All control animals ovulated and were either fully fertile (n = 15) or were mated to infertile males (n = 4). In addition, proven-fertile male domestic rabbits (n = 3) were immunized s.c. and boosted three times with fertilin beta. Only one animal subsequently showed impaired fertility. These results show that in the rabbit, high levels of circulating sperm-reactive anti-fertilin antibodies and the presence of vaginal IgG does not ensure infertility.

Cloning and expression of recombinant rabbit fertilin

Fertilin is a sperm surface protein complex which is reported to play an essential role in sperm-egg fusion in mammals. It is comprised of two related subunits, alpha and beta, both of which are glycosylated and have cytoplasmic and extracellular domains. This protein has been reported to play an essential role in sperm-egg fusion in mammals. We report on the cloning and sequencing of the complete cDNA sequences of both subunits from rabbit testis, and the production of recombinant proteins for testing their potential as antigens for use in an immunocontraceptive vaccine to control wild rabbit populations. The cDNAs for rabbit fertilin alpha and beta (Genbank accession numbers, U46069 and U46070) are predicted to encode proteins of 919 and 751 amino acids, respectively, and to show significant levels of homology to fertilin subunits isolated from other species. Analysis of the predicted protein sequences of fertilin alpha but not beta reveals the presence of 21 direct repeats of the hexameric sequence A/PPPPEA at the extreme carboxy terminus, similar to what has been described for a fertilin alpha gene isoform in the monkey. DNA sequences corresponding to the predicted mature alpha and beta fertilin subunits were individually cloned into a bacterial expression system, and the recombinant proteins were used to raise polyclonal antibodies in mice. These antibodies detect components of the native fertilin complex from rabbit sperm.

A mobile group II intron of a naturally occurring rearranged mitochondrial genome in Kluyveromyces lactis

Mitochondrial intron content is variable in the yeast Kluyveromyces lactis. Strains can be divided into three classes depending on the structure of the cytochrome oxidase subunit 1 (COX1) gene: (1) those containing intron K1 cox1.1, (2) those containing K1 cox1.2, 3 and 4 and, (3) those that contain all four introns. In addition, strains belonging to the first class (designated Type B strains), have an altered mitochondrial gene order relative to strains from classes (2) and (3) (Type A, Hardy et al. 1989). Crossing experiments reveal that K1 cox1.1 (a group II intron) transfers at high frequency (89%) to mitochondrial genomes lacking this intron. By contrast, the mobility of the remaining introns (all group I) is of the order of 7%.

Nucleotide sequence of the COX1 gene in Kluyveromyces lactis mitochondrial DNA: evidence for recent horizontal transfer of a group II intron

The cytochrome oxidase subunit 1 gene (COX1) in K. lactis K8 mtDNA spans 8,826 bp and contains five exons (termed E1-E5) totalling 1,602 bp that show 88% nucleotide base matching and 91% amino acid homology to the equivalent gene in S. cerevisiae. The four introns (termed K1 cox1.1-1.4) contain open reading frames encoding proteins of 786, 333, 319 and 395 amino acids respectively that potentially encode maturase enzymes. The first intron belongs to group II whereas the remaining three are group I type B. Introns K1 cox1.1, 1.3, and 1.4 are found at identical locations to introns Sc cox1.2, 1.5 a, and 1.5 b respectively from S. cerevisiae. Horizontal transfer of an intron between recent progenitors of K. lactis and S. cerevisiae is suggested by the observation that K1 cox1.1 and Sc cox1.2 show 96% base matching. Sequence comparisons between K1 cox1.3/Sc cox1.5 a and K1 cox1.4/Sc cox1.5 b suggest that these introns are likely to have been present in the ancestral COX1 gene of these yeasts. Intron K1 cox1.2 is not found in S. cerevisiae and appears at an unique location in K. lactis. A feature of the DNA sequences of the group I introns K1 cox1.2, 1.3, and 1.4 is the presence of 11 GC-rich clusters inserted into both coding and noncoding regions. Immediately downstream of the COX1 gene is the ATPase subunit 8 gene (A8) that shows 82.6% base matching to its counterpart in S. cerevisiae mtDNA.

Nucleotide sequence of the cytochrome oxidase subunit 2 and val-tRNA genes and surrounding sequences from Kluyveromyces lactis K8 mitochondrial DNA

The nucleotide sequence of the cytochrome oxidase subunit 2 (cox2) and val-tRNA genes and surrounding regions from Kluyveromyces lactis mitochondrial DNA is reported. Analysis of the coding region shows that the codons CUN (Thr), CGN (Arg) and AUA (Met) are absent in this gene. A single sequence, ATATAAGTAA, identical to the baker's yeast mtRNA polymerase recognition site, was detected upstream of val-tRNA. This sequence is absent from regions between val-tRNA-cox2 and cox2-cox1. In addition a sequence AATAATATTCTT, identical to the mRNA processing site in other yeast mitochondrial genomes is present 32-43 bp downstream to the TAA stop codon for the cox2 gene. Another short conserved sequence of 5 bp, TCTAA, is present upstream of the coding regions of cox2 genes in several yeasts, including K. lactis, but is not present upstream of other genes. Comparison of cox2 sequences from other organisms indicates that the mitochondrial DNA of K. lactis is closely related to that of Saccharomyces cerevisiae.

Deletions and rearrangements in Kluyveromyces lactis mitochondrial DNA

Three classes of respiratory deficient mutants have been isolated from a fusant between Kluyveromyces lactis and Saccharomyces cerevisiae that contains only K. lactis mtDNA. One class (15 isolates), resemble rho 0 mutants of S. cerevisiae as they lack detectable mtDNA. A second class (16 isolates), resemble point mutations (mit-) or nuclear lesions (pet-) of S. cerevisiae as no detectable change is found in their mtDNA. The third class (five isolates), with deletions and rearrangements in their mtDNA are comparable to S. cerevisiae petite (rho-) mutants. Surprisingly, three of the five deletion mutants have lost the same 8.0 kb sector of the mtDNA that encompasses the entire cytochrome oxidase subunit 2 gene and the majority of the adjacent cytochrome oxidase subunit 1 gene. In the other strains, deletions are accompanied by complex rearrangements together with substoiciometric bands and in one instance an amplified sector of 800 bp. By contrast to G + C rich short direct repeats forming deletion sites in S. cerevisiae mtDNA, excision of the 8.0 kb sector in K. lactis mtDNA occurs at an 11 bp A + T rich direct repeat CTAATATATAT. The recovery of three strains manifesting this deletion suggests there are limited sites for intramolecular recombination leading to excision in K. lactis mtDNA.

Cocoa feeding and human lactose intolerance

On the basis of evidence of the suppressing effect of cocoa on human lactose intolerance, a feeding study was conducted on 35 subjects with a commercial chocolate-milk formula. Variables studied were breath hydrogen level (BHL), symptoms, and onset time. Data from repeated feeding were analyzed by paired t tests. The addition of cocoa significantly reduced BHL (p less than 0.005) as well as the symptom score of both bloating (p less than 0.05) and cramping (p less than 0.025). Individual lactose intolerance levels ranged from 5% (basal milk) to 12.5% with an average of 7.8% upon consumption of 250 mL milk. Having both plain and cocoa formulas contain sucrose and carrageenan led to a conclusion that the suppressive effect of cocoa observed was independent of the presence of sucrose and carrageenan. Ninety-five percent of the subjects responded positively (BHL greater than 17 ppm) to the plain and 51% to the cocoa formula.

Pi exchange mediated by the GlpT-dependent sn-glycerol-3-phosphate transport system in Escherichia coli

The GlpT system for sn-glycerol-3-phosphate transport in Escherichia coli is shown to catalyze a rapid efflux of Pi from the internal phosphate pools in response to externally added Pi or glycerol-3-phosphate. A glpR mutation, which results in constitutive expression of the GlpT system, is responsible for this rapid Pi efflux and the arsenate sensitivity of several laboratory strains, including the popular strain C600. Glucose and other phosphotransferase system sugars inhibit Pi efflux by repressing glpT expression.

Rapid turnover of mannitol-1-phosphate in Escherichia coli

The phosphate moiety of D-mannitol-1-phosphate in Escherichia coli is subject to rapid turnover and is in close equilibrium with Pi and the phosphorus of fructose-1,6-bisphosphate. These three compounds account for the bulk of 32P label found in cells after several minutes of uptake of 32Pi and mannitol-1-phosphate represents some 30% of this label. Mannitol-1-phosphate occurs in E. coli grown on a variety of carbon sources, in the absence of D-mannitol, and is synthesized de novo even in mutants lacking mannitol-1-phosphate dehydrogenase. The mannitol moiety of mannitol-1-phosphate was not affected during the total chase of the P moiety, which exchanged with a half-life of about 30 s. These findings suggest that the rapid equilibration of the phosphorus is a function of an enzyme, possibly a component of the phosphotransferase system, capable of forming a complex that allows the exchange of the phosphate without the equilibration of the mannitol moiety with free mannitol.

Conversion of D-mannitol to D-ribose: a newly discovered pathway in Escherichia coli

A mutant (mtlD) strain of Escherichia coli unable to oxidize mannitol-1-phosphate to fructose-6-phosphate was used to study the fate of mannitol-1-phosphate. D-[1-14C]mannitol entered the cells via the phosphotransferase system and was phosphorylated equally at carbon 1 or 6. The label disappeared gradually from the mannitol-1-phosphate pool, and some 60% of the 14C was recovered in nucleic acids. Ribose was isolated from the purified RNA. The 14C label distribution in the isolated ribose precluded a simple hexose-to-pentose conversion by elimination of one terminal carbon from mannitol-1-phosphate. The 14C from mannitol-1-phosphate that did not enter macromolecules was found in CO2 and in some organic, non-phosphorylated compounds that were not identified. We suggest that the de novo synthesis of mannitol-1-phosphate in E. coli may be a reaction specifically dedicated to the biosynthesis of ribose.

Characterization of Barmah forest virus: an alphavirus with some unusual properties

Barmah Forest virus has been characterized in a number of ways including electron microscopy of infected cells; physical studies of the virion, its RNA, and associated proteins; N-terminal sequence analysis of the two envelope glycoproteins; studies of macromolecular species present in infected cells; and serological cross-reactions with alphaviruses and bunyaviruses. From these results Barmah Forest virus is clearly an alphavirus since the structure of the virion, the mode of replication, and the macromolecular species present in infected cells are typical of alphaviruses. The N-terminal regions of the two glycoproteins E1 and E2 show extensive sequence homology (approximately 50%) with those of other alphaviruses. Barmah Forest virus cross-reacts in hemagglutination inhibition tests, although not in complement fixation tests or infectivity neutralization tests, with other alphaviruses. In some of its properties Barmah Forest virus is unusual, however. It cross-reacts in complement fixation and hemagglutination inhibition tests with Umbre virus, a bunyavirus, which originally led it to be classified as a bunyavirus; the glycosylation pattern of E2 of Barmah Forest virus appears to differ from that of other alphaviruses; and the sedimentation coefficient of the virion appears to be slightly less than that of other alphaviruses.