Felid sex identification based on noninvasive genetic samples

We developed two tests for sex identification of felids using y‐chromosome deletions in the zinc‐finger and amelogenin regions. These tests provide positive results for both males and females, while reducing the need to co‐amplify microsatellites to test for DNA quality in hair and scat samples. Furthermore, the y‐chromosome deletions are absent in a wide‐range of prey species; thus, when these tests are used on scat samples, potential contamination caused by prey DNA incidentally extracted, is minimized.     

Immunogenicity of a non-class I MHC expressing murine tumor transfected with the influenza virus hemagglutinin or murine interleukin-2 genes

Summary The transfection of murine SP1 tumor cells with the hemagglutinin (HA) gene of influenza virus results, after fluorescent-activated cell sorting (FACS), in the selection of high-HA-expressing cell lines called H4A and H4B. Both lines fail to grow in syngeneic animals at doses that result in 100% tumor take of non-transfected tumor cells. Both grow in immunosuppressed mice. SP1 and H4A or H4B cells express few class I major histocompatibility complex (MHC) antigens but do express class II IA^k antigens. H4A or H4B cells engender a cytotoxic T lymphocyte (CTL) response but cannot protect against a challenge with SP1 cells. This CTL response is inhibited by anti-CD4 but not anti-CD8 antibodies. Using FACS, we were able to select a population (called H5AK5) with high class-I MHC antigen expression. Like H4A and H4B, H5AK5 cells fail to grow in syngeneic animals but do grow in immunosuppressed mice. However, unlike H4A or H4B, H5AK5 can induce protection against a challenge with 1 × 10⁵ SP1 cells. These studies indicate that the immunogenicity ofHA-transfected SP1 cells may correlate with the cell-surface expression of class II MHC antigens. However, HA-expressing SP1 cells seem able to induce a protective response against a parent SP1 cell challenge only if they also express class I MHC antigens. This view is supported by the observations that SP1 cells expressing murine interleukin-2 do not express class I MHC antigens, fail to grow in syngeneic animals, do grow in immunosuppressed mice but do not protect against a challenge with parental SP1 cells.This work was supported by The Clayton Fund, The Sid W. Richardson Foundation and PHS grants CA 39853 and 41525. Toshiyuki Itaya is a visiting scientist supported by the Smith Education Fund of the Department of Cell Biology. Troy Fiesinger is a summer research investigator sponsored by The University of Texas M. D. Anderson Cancer Center Summer Program for College Students     

Preparation and properties of the water-soluble chlorophyll-bovine serum albumin complexes

By mixing chlorophyll (Chl) a or b with a dense bovine serum albumin solution, the water-soluble Chl-bovine serum albumin complexes were prepared. These complexes, eluted near the void volume on a gel filtration, were separated well from unreacted bovine serum albumin, indicating an aggregation of such molecules in the complexes. Preparation of chlorophyllide (Chlide) a- or Chlide b-bovine serum albumin complex was unsuccessful, while the phytol-, and β-carotene-bovine serum albumin complexes could be obtained. Chls in the Chl-bovine serum albumin complexes had the following characteristics. (i) Main absorption peak of Chl a or b in the red region occurred at 675 nm or 652 nm, respectively. The Chl a-bovine serum albumin complex having absorption peak at 740 nm was also prepared. As compared with the stabilities of Chl a and b in Triton X-100. (ii) Both Chls in the bovine serum albumin-complexes were stable against oxidative stresses, such as photobleaching, Fenton reagent, peroxidase-H₂O₂ system. But (iii) they were easily hydrolyzed by chlorophyllase. These properties of Chls in the bovine serum albumin-complexes were similar to those of Chls in the isolated light-harvesting Chl a/b protein complex. A possible localization of Chls within the bovine serum albumin complexes was suggested that the porphyrin moiety of Chl was buried in bovine serum albumin; however, the hydrophilic edge of porphyrin ring, adjacent to the phytol group, occurred in the hydrophilic region of a bovine serum albumin molecule.     

Enzymatic methylation of DNA and poly(dG-dC) X poly(dG-dC) modified by 4-acetoxyaminoquinoline-1-oxide, the ultimate carcinogen of 4-nitroquinoline-1-oxide

Both the initial velocity and the overall methylation of Ac-4HAQO modified DNA by a calf brain DNA (cytosine-5-)-methyltransferase are increased as compared to native DNA. The affinity of the modified DNA for the enzyme decreases as a function of the extent of the modification. Heat-denatured, single-stranded DNA shows exactly the opposite results: the more it is modified, the less it is methylated. The poly(dG-dC) X poly(dG-dC) modified by 4NQO is as well methylated as the non-modified one. The carcinogen may induce a tertiary structure favouring the 'walking' of the enzyme along the DNA. The hypermethylation caused by this carcinogen could have a significance in gene activity and cellular differentiation.     

Molecular Diagnosis of Meloidogyne Species

Genetic variation within nuclear and mitochondrial DNA of Meloidogyne species and host races has been evaluated for the development of root-knot nematode molecular diagnostics. This review summarizes the distinctive features of several useful DNA-based assays for plant-parasitic nematodes, focusing upon the direct application of these procedures for Meloidogyne detection, identification, and systematics.     

The effect of glucose on the expression of extracellular protein genes by Staphylococcus aureus strain V8

The bacteria from overnight cultures (20 h) of S. aureus V8 and exp negative mutant K6812-1, grown, aerobically, in 3% (w/v) Tryptone Soya Broth, at 37 degrees C, were resuspended in fresh medium, in the case of the parent strain +/- 1% (w/v) glucose, without change in bacterial density. During a 6 h incubation period there was an approximate doubling of bacterial density, to the same level, in each case. However, exoprotein production by the mutant was only 20% that of the parent whilst the addition of glucose to the V8 strain resulted in a tenfold reduction in the exoprotein formed. SDS-polyacrylamide gel electrophoresis showed that the exoprotein patterns of both organisms after 6 h incubation were the same as those observed in the overnight cultures whilst the presence of 1% (w/v) extra glucose changed the pattern produced by the parent to one similar to that of the mutant. The results showed that conditions which lead to the rapid formation of glucose catabolites produced an effect consistent with the inhibition of the activity of the exp gene product.     

Cellular differentiation in relation to water vapour absorption in the rectal complex of the mealworm, Tenebrio molitor

Larvae of the mealworm beetle Tenebrio molitor, are able to absorb water vapour from subsaturated air, but adults cannot. This functional difference is paralleled by structural differences in the cryptonephridial rectal complex, the site of vapour absorption in the larva. Very distinctive differences occur in the rectal pad epithelium and these are reported in detail for the first time. The cells of the larval rectal pad are very closely apposed, forming a structural, and presumably functional, unit, whereas the cells of the adult rectal pad are more clearly separate. Intracellular organization also shows clear differences. These differences indicate that the rectal epithelium may play a more important role in vapour absorption than recently ascribed to it. Other, less striking, differences in the cryptonephric Malpighian tubules and perinephric membrane as previously recorded have largely been confirmed. Morphometric analysis suggests that diffusion alone could account for the observed absorption of water vapour across the larval system from rectal lumen to the lumen of the cryptonephric tubules, but this does not rule out the possibility that other transporting mechanisms are also involved. Radial diffusion and antero-posterior gradients may be facilitated by the predominently radial and circumferential arrangement of the rectal pad cells and the surrounding cryptonephric tubules. Reinvestigation of the isolating perinephric membrane and its insertion onto the rectal cuticle supports the conclusions that insertion occurs only posteriorly. The model incorporating anterior as well as posterior insertion does not apply. The membrane posteriorly encloses a single perirectal space between rectum and tubules and in this region no perinephric or peritubular space is found between inner and outer regions of the membrane. This is the region where maximal gradients occur across the system.     

Reaction center light harvesting B875 complexes from Rhodocyclus gelatinosus: characterization and identification of quinones

Reaction center-B875 pigment-protein complexes were purified from Rhodocyclus gelatinosus. The proteic components consist of 7–8 polypeptides among which some were identified by their apparent molecular weights: the light harvesting B875 polypeptides and of 8 and 6 kDa, reaction center L (23 kDa), M (28 kDa) and H (34 kDa), cytochrome c (43 kDa). Four c-type hemes were found per reaction center. Flash-induced absorbance changes showed the presence of both Q_A and Q_B in the complex. Charge recombination times were determined to be: 1.16±0.2 (n=30) for P⁺Q_AQ_B ^- and 7–10 ms for P⁺Q_A ^- in presence of herbicides. From quinone analysis on one hand and kinetics of charge recombination on the other hand, we proposed that in the reaction center of Rhodocyclus gelatinosus Q_A is menaquinone 8 and Q_B is ubiquinone 8.     

Analysis of woody vegetation of Corbett National Park,India

The heterogeneous vegetation mosaic of the South Turkana region of north Kenya is associated with diversity in the region's physical environment. The abundance and distribution of the dominant species are related to gradients in those abiotic factors that influence water availability, including precipitation, soil texture, and topographic relief. Research focused on three Acacia species that are a major component of the Turkana vegetation; A. tortilis, A. senegal, and A. reficiens. These species each exhibit a different response to variations in abiotic factors. Consequently, species abundance varies independently across the landscape, creating a continuum of intergrading populations. Community types can be identified within the mosaic of intergrading populations. Although community borders are not discrete due to continual change in species abundance, types are identifiable and are repeated in areas with similar environmental conditions. The landscape patterns are representative of Whittaker's (1953) climaxas-pattern, with communities created by individual patterns of populations responding to environmental gradients, creating a continuum of community change across the landscape.