FLP-mediated site-specific recombination in microinjected murine zygotes

The FLP recombinase of yeast catalyses site-specific recombination between repeated FLP recombinase target (FRT) elements in yeast and in heterologous system (Escherichia coli, Drosophila, mosquito and cultured mammalian cells). In this report, it is shown that transient FLP recombinase expression can recombine and activate an extrachromosomal silent reporter gene following coinjection into fertilized one-cell mouse eggs. Furthermore, it is demonstrated that introduction of a FLP-recombinase expression vector into transgenic one-cell fertilized mouse eggs induces a recombination event at a chromosomal FRT target locus. The resulting event occured at the one-cell stage and deleted a chromosomal tandem array of a FRT containinglacZ expression cassette down to one or two copies. These results demonstrate that the FLP recombinase can be utilized to manipulate the genome of transgenic animals and suggest that FLP recombinase-mediated plasmid-to-chromosome targeting is feasible in microinjected eggs.     

Establishment and characterization of a novel human myoepithelial cell line and matrix-producing xenograft from a parotid basal cell adenocarcinoma

Summary Myoepithelial cells exert important paracrine effects on epithelial morphogenesis and mitogenesis through direct cell-cell interactions and through synthesis of a basement membrane extracellular matrix. To study these effects further, this study established the first immortalized human myoepithelial cell line, HMS-1, and transplantable xenograft, HMS-X, from the rare parotid basal cell adenocarcinoma. The cell line exhibited a fully differentiated myoepithelial phenotype and the xenograft exhibited the rare property of accumulating an abundant extracellular matrix composed of both basement membrane and nonbasement membrane components with the latter predominating. With HMS-1 as a feeder layer, dramatic and specific induction of epithelial morphogenesis (sheroid formation) occurred with selected normal epithelial and primary carcinoma target cells. HMS-1 and HMS-X provide distinct advantages over the conventional murine matrices in existence. They will be invaluable in future studies of human tumor-myoepithelial and matrix interactions important for tumor cell growth, invasion, and metastasis.     

Synthesis of citrate from phosphoenolpyruvate and acetylcarnitine by mitochondria from rabbit, pigeon and rat liver: Implications for lipogenesis

Rabbit, pigeon and rat liver mitochondria convert exogenous phosphoenolpyruvate and acetylcarnitine to citrate at rates of 14, 74 and 8 nmol/15 min/mg protein. Citrate formation is dependent on exogenous HCO3, is increased consistently by exogenous nucleotides (GDP, IDP, GTP, ADP, ATP) and inhibited strongly by 3-mercaptopicolinate and 1,2,3-benzenetricar☐ylate. Citrate is not made from pyruvate alone or combined with acetylcarnitine. Pigeon and rat liver mitochondria make large amounts of citrate from exogenous succinate, suggesting the presence of an endogenous source of acetyl units or a means of converting oxalacetate to acetyl units. Citrate synthesis from succinate by pigeon and rabbit mitochondria is increased significantly by exogenous acetylcarnitine. Pigeon and rat liver contain 80 and 15 times, respectively, more ATP:citrate lyase activity than does rabbit liver. Data suggest that mitochondrial phosphoenolpyruvate car☐ykinasein vivo could convert glycolysis-derived phosphoenolpyruvate to oxalacetate that, with acetyl CoA, could form citrate for export to support cytosolic lipogenesis as an activator of acetyl CoA car☐ylase, a carbon source via ATP:citrate lyase and NADPH via NADP: malate dehydrogenase or NADP: isocitrate dehydrogenase.     

A controlled study of the effects of EEG biofeedback on cognition and behavior of children with attention deficit disorder and learning disabilities

Eighteen children with ADD/ADHD, some of whom were also LD, ranging in ages from 5 through 15 were randomly assigned to one of two conditions. The experimental condition consisted of 40 45-minute sessions of training in enhancing beta activity and suppressing theta activity, spaced over 6 months. The control condition, waiting list group, received no EEG biofeedback. No other psychological treatment or medication was administered to any subjects. All subjects were measured at pretreatment and at posttreatment on an IQ test and parent behavior rating scales for inattention, hyperactivity, and aggressive/defiant (oppositional) behaviors. At posttreatment the experimental group demonstrated a significant increase (mean of 9 points) on the K-Bit IQ Composite as compared to the control group (p<.05). The experimental group also significantly reduced inattentive behaviors as rated by parents (p<.05). The significant improvements in intellectual functioning and attentive behaviors might be explained as a result of the attentional enhancement affected by EEG biofeedback training. Further research utilizing improved data collection and analysis, more stringent control groups, and larger sample sizes are needed to support and replicate these findings.This research was supported by an equipment grant by Autogenics Systems. Portions of this paper were presented at the annual convention of the Association of Applied Psychophysiology and Biofeedback, March, 1993 in Los Angeles and at the annual meeting of the Biofeedback Society of California, November, 1992 in Monterey, California. The authors gratefully acknowledge Todd Fischer and Paul Clopton for their valuable assistance in statistical analysis for this article.     

Purification and characterisation of an intracellular carbonic anhydrase from the unicellular green alga Coccomyxa

An intracellular carbonic anhydrase (CA; EC 4.2.1.1) was purified and characterised from the unicellular green alga Coccomyxa sp. Initial studies showed that cultured Coccomyxa cells contain an intracellular CA activity around 100 times higher than that measured in high-CO₂-grown cells of Chlamydomonas reinhardtii CW 92. Purification of a protein extract containing the CA activity was carried out using ammonium-sulphate precipitation followed by anion-exchange chromatography. Proteins were then separated by native (non-dissociating) polyacrylamide gel electrophoresis, with each individual protein band excised and assayed for CA activity. Measurements revealed CA activity associated with two discrete protein bands with similar molecular masses of 80 +5 kDa. Dissociation by denaturing polyacrylamide gel electrophoresis showed that both proteins contained a single polypeptide of 26 kDa, suggesting that each 80-kDa native protein was a homogeneous trimer. Isoelectric focusing of the 80-kDa proteins also produced a single protein band at a pH of 6.5. Inhibition studies on the purified CA extract showed that 50% inhibition of CA activity was obtained using 1 M azetazolamide. Polyclonal antibodies against the 26-kDa CA were produced and shown to have a high specific binding to a single polypeptide in soluble protein extracts from Coccomyxa cells. The same antiserum, however, failed to cross-react with soluble proteins isolated from two different species of green algae, Chlamydomonas reinhardtii and Chlorella vulgaris. Correspondingly, antisera directed against pea chloroplastic CA, extracellular CA from C. reinhardtii and human CAII, showed no cross-hybridisation to the 26-kDa polypeptide in Coccomyxa. The 26-kDa protein was confirmed as being a CA by N-terminal sequencing of two internal polypeptide fragments and alignment of these sequences with that of previously identified CA proteins from several different species.Abbreviations CA carbonic anhydrase - CCM CO₂-concentrating mechanism - IEF isoelectric focusing - Rubisco ribulose-l,5-bisphosphate carboxylase/oxygenase We would like to thank Drs. Cecilia Forsman, Inga-Maj Johansson and Nalle Jonsson for their valuable advice concerning the isolation of CA. This work was supported by the Swedish Natural Research Council and Seth M. Kempes Memorial foundation.     

The yellow-cheeked gibbon (Hylobates gabriellae) in nam bai cat tien (southern vietnam) revisited

Data concerning the status, habitat, and vocalizations of yellow-cheeked crested gibbons (Hylobates gabriellae) were collected during a short field trip to the Nam Bai Cat Tien National Park (southern Vietnam). Nam Bai Cat Tien may be the southernmost locality where crested gibbons (i.e. theHylobates concolor group) still survive. Fewer songs were heard at Nam Bai Cat Tien National Park than at other crested gibbon sites visited by the author. At least two gibbon groups appear to have been greatly reduced in number since previous surveys in the park. There is some evidence that both the gibbon population and the gibbon habitat in Nam Bai Cat Tien are disturbed. The first case of a great call solo song in wild gibbons of theconcolor group is reported. Great calls ofH. gabriellae are described and documented with sonagrams for the first time. They differ from those previously described forH. leucogenys.     

Organization of the mitochondrial Cob 2 pseudogene in different lines of rice

In the fertile rice line IR 36 there are two copies of the apocytochrome b (cob) gene: a functional copy, cob 1, and a pseudogene, cob 2 (Kaleikau et al. 1992). In a survey of diverse rice lines, we found that cob 2 was absent in the wild abortive(WA)-type cytoplasmic male-sterile cytoplasm, but was present in the fertile lines. While cob 1 was conserved among all the lines, fertile and sterile, the cob 2 region was different in the fertile lines tested. The 5′ regions of most cob 2 loci were similar to cob 1 (about 4 kb of the flanking region and most of the coding region), but the 3′ region varied among different fertile lines. The point of divergence, the break-point, from the cob 1 sequence was conserved in all the cob 2 regions tested. In all the cob 2 regions, this break-point seems to be linked to the variable region of cob 2 through a conserved 192-bp segment, which is not a part of cob 1. It is proposed that the cob 2 regions could have been produced by recombination or insertion events involving cob 1 and the 192-bp segment which is present at different locations in the mitochondrial genomes of the various rice lines.     

Morphological responses by Bosmina longirostris and Eubosmina tubicen to changes in copepod predator populations during a whole-lake acidification experiment

Changes in zooplankton populations during the experimental acidilicationof Little Rock Lake provided an opportunity to examine specificmechanisms underlying the morphological responses of bosminidsto changing predation pressure. Two large copepods, Epischuralacustris and Mesocyclops edax, disappeared from the lake'sacidified basin in 1986 and 1989, respectively, while a smallercopepod predator, Tropocyclops extensus, increased during laterstages of acidification. The two bosminid species showed distinctlydifferent responses coinciding with the changes in copepod predation.Bosmina longirostris exhibited a significant decrease in mucrolength with the decline of M.edax and E.lacustris. Its meanbody and antennule length, however, did not change. We suggestthat the decoupling of B.longirostris mucro length and antennulelength may have been related to the persistence of the smallercopepod predator, T.extensus. Eubosmina tubicen showed no apparentresponse to declines in M.edax and E.lacustris abundance ineither mean mucro, antennule or body length. Allometric analysesindicated, however, that mucro length was related to size-dependentcopepod predation for both B.longirostris and E.tubicen.