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361.
Developing taste buds in the anterior mandibular floor of perihatching
chicks were studied by high voltage electron microscopic autoradiography in
order to identify proliferating gemmal cell types. Montaged profiles of 29
taste buds in five cases euthanized between embryonic day 21 and
posthatching day 2 were analyzed after a single [3H]thymidine injection
administered on embryonic day 16, 17 or 18. Results showed that dark cells
comprised 55% of identified (n = 900 cells) and 62% of labeled (n = 568
cells) gemmal cells as compared with light, intermediate, basal or
perigemmal bud cells. Dark cells had both a greater (P < 0.05) number of
labeled cells and a greater amount of label (grains/nucleus) than the other
four bud cell types, irrespective of injection day. The nuclear area
(micron 2) of dark cells was not significantly larger (P > 0.05) than
that of the other gemmal cell types and therefore cannot account for the
greater amount for label in the dark cells. Interestingly, only dark cells
showed a positive correlation (P < 0.003) between amount of label and
nuclear area. Results suggest that, during the perihatching period of
robust cell proliferation, dividing dark cells may give rise primarily, but
not exclusively, to dark cell progeny.
相似文献
362.
Expression cloning of a receptor for C5a anaphylatoxin on differentiated HL-60 cells 总被引:12,自引:0,他引:12
A cDNA clone encoding the human C5a anaphylatoxin receptor has been isolated by expression cloning from a CDM8 expression library prepared from mRNA of human myeloid HL-60 cells differentiated to the granulocyte phenotype with dibutyryladenosine cyclic monophosphate. The cDNA clone was able to transfer to COS-7 cells the capacity to specifically bind iodinated human recombinant C5a. The cDNA was 2.3 kb long, with an open reading frame encoding a 350-residue polypeptide. Cross-linking of iodinated C5a to the plasma membrane of transfected COS cells revealed a complex with an apparent molecular mass of 52-55 kDa, similar to that observed for the constitutively expressed receptor in differentiated HL-60 cells or human neutrophils. Although differentiated HL-60 cells display a single class of binding sites, with a dissociation constant of approximately 800-900 pM, the C5a-R cDNA, expressed in COS cells, generates both high-affinity (1.7 nM) and low-affinity (20-25 nM) receptors. Sequence comparison established that the degree of sequence identity between the C5a receptor and the N-formylpeptide receptor is 34%. 相似文献
363.
In the continuation of the concepts of E-Motion mis-sight and Temporo-Spatial Processing Disorders (TSPD) of multi-sensory stimuli, we carry on our developmental theory of autism. We first remind that TSPDs consist in difficulties and peculiarities perceiving and integrating online the temporal and spatial characteritics of the incoming sensory events in the visual, auditory and proprioceptive modalities. Via the clinical manifestations exhibited by a baby at risk for autism, some self reports of autistic adults, and several experimental results, we show how the TSPDs might be central for the main behavioral, imitative, sensory-motor and cognitive disorders of at least some autistic persons. Then we present a new concept, the Multi-system Brain Disconnectivity-Dissynchrony (MBD), which represents the various degrees of under- or over- functional connectivity and hypo- or hyper-synchronization between numerous brain regions, and show that MBD might consitute the neurophysiological basis of TSPDs. We finally present the therapeutical applications and clinical perspectives that emerge from our approach, in particular via slowing down the environmental visual and auditory signals. 相似文献
364.
S Tardif M A Sirard R Sullivan J L Bailey 《Molecular reproduction and development》1999,54(3):292-302
Our objectives were to incorporate ATP-gamma-(32)P into boar sperm to radiolabel endogenous phosphoproteins and compare phosphorylation patterns from sperm incubated in capacitating (CM) and non-capacitating conditions (NCM). Sperm were electroporated (1000 V/cm, 125 microF/cm, 65 Omega/cm, 0.3 msec) with ATP-gamma-(32)P which moderately decreased sperm viability (P < 0.01), but did not affect motility (P = 0.34) or the appearance of spontaneous acrosome reactions (P = 0.49). Sperm incubated in CM for 3 hr underwent capacitation, determined by the ability to undergo ionophore-induced acrosome reactions (P = 0.05). Furthermore, more sperm in CM than in NCM exhibited chlortetracycline (CTC) pattern B (capacitated) fluorescence (P = 0.01). SDS-PAGE, autoradiography and phosphoimagery of extracted, (32)P-labeled sperm proteins revealed a subset of phosphoproteins (Mr 28,000-60,000) from cells incubated in CM, whereas only two phosphorylated proteins were evident from sperm in NCM (44 and 57 kDa). The appearance of phosphoproteins increased concomitant with capacitation (P = 0.05). In NCM, the 44 kDa protein was unaffected by time (P > 0.05) and the 57 kDa phosphoprotein increased after capacitation (P = 0.05). Computer-assisted analysis revealed that the percentage of motile sperm in either medium decreased with time, and CM only transiently maintained motility over NCM (P >/= 0.02). ATP-gamma-(32)P can, therefore, be incorporated into porcine sperm to radiolabel endogenous phosphoproteins, and the different profiles from sperm incubated in NCM versus CM suggest that capacitation is mediated by signaling events involving protein phosphorylation. 相似文献
365.
Suzette D. Tardif Conrad B. Richter Robert L. Carson 《American journal of primatology》1984,6(4):377-380
The survival rate for offspring of mothers who either had or did not have previous experience rearing younger siblings was compared in two callitrichid species, Callithrix jacchus and Saguinus oedipus. Offspring of mothers with sibling-rearing experience had a higher survival percentage than offspring of inexperienced mothers in both species. While 50–60% of offspring of inexperienced C. jacchus mothers survived, no offspring of inexperienced S. oedipus mothers survived. The results suggest that sibling-rearing experience is necessary for adequate maternal behavior in S. oedipus, but not necessary to the development of maternal behavior in C. jacchus. Effects of previous sibling-rearing experience of S. oedipus fathers on offspring survival were also examined. Whether the father had rearing experience was not related to the survival of their offspring. 相似文献
366.
Identification of a gene, rgg, which regulates expression of glucosyltransferase and influences the Spp phenotype of Streptococcus gordonii Challis. 下载免费PDF全文
Streptococcus gordonii Challis was previously shown to give rise to phase variants expressing high (Spp+) or low (Spp-) levels of extracellular glucosyltransferase (GTF) activity. Here, shotgun cloning of an S. gordonii Spp+ chromosomal digest resulted in a chimeric plasmid (pAM5010) able to complement the Spp- phenotype. In addition, introduction of pAM5010 into an Spp+ strain resulted in a 10-fold increase in GTF expression. Deletion analysis of pAM5010 identified a 1.2-kb DNA segment which exhibited the same functional properties as pAM5010. Nucleotide sequence analysis of this region revealed a gene approximately 1 kb in size. The gene was designated rgg. Disruption of the chromosomal rgg gene open reading frame in an Spp+ strain resulted in strain DS512, which displayed an Spp(-)-like phenotype and had 3% of wild-type GTF activity. A plasmid containing the rgg gene was able to complement the DS512 phenotype and significantly increase GTF expression above wild-type levels. Sequence analysis and other data showed that the S. gordonii GTF determinant, designated gtfG, is located 66 bp downstream of the rgg gene. The sequence also revealed interesting inverted repeats which may play a role in the regulation of gtfG. We conclude that rgg positively regulates the expression of GTF and influences expression of the Spp phenotype. 相似文献
367.
Cory L. Nykiforuk Yin Shen Elizabeth W. Murray Joseph G. Boothe David Busseuil Eric Rhéaume Jean‐Claude Tardif Alexandra Reid Maurice M. Moloney 《Plant biotechnology journal》2011,9(2):250-263
Apolipoprotein AI Milano (ApoAIMilano) was expressed as a fusion protein in transgenic safflower seeds. High levels of expression corresponding to 7 g of ApoAIMilano per kilogram of seed have been identified in a line selected for commercialization. The ApoAIMilano fusion protein was extracted from seed using an oilbody‐based process and matured in vitro prior to final purification. This yielded a Des‐1,2‐ApoAIMilano product which was confirmed by biochemical characterization including immunoreactivity against ApoAI antibodies, isoelectric point, N‐terminal sequencing and electrospray mass spectrometry. Purified Des‐1,2‐ApoAIMilano readily associated with dimyristoylphosphatidylcholine in clearance assays comparable to Human ApoAI. Its biological activity was assessed by cholesterol efflux assays using Des‐1,2‐ApoAIMilano:1‐palmitoyl‐2‐oleoyl phosphatidylcholine complexes in vitro and in vivo. This study has established that high levels of biologically functional ApoAIMilano can be produced using a plant‐based expression system. 相似文献
368.
Michael L. Power Joselyn M. Artavia Suzette D. Tardif 《Obesity (Silver Spring, Md.)》2013,21(9):1891-1899
Objective : Increasing prevalence of childhood obesity and associated risks of adult type disease have led to worldwide concern. It remains unclear how genetic predisposition, environmental exposure to obesogenic food, and developmental programming interact to lead to overweight and obese children. The development of a nonhuman primate model of obesity, and particularly juvenile obesity, is an important step to elucidating the factors associated with obesity and evaluating intervention strategies. Design and Methods : Infant marmosets were followed from birth to 12 months of age. Feeding phenotypes were determined through the use of behavioral observation, solid food intake trials, and liquid feeding trials monitored via lickometer. Results : Marmosets found to be obese at 12 months of age (more than 14%body fat) start consuming solid food sooner and initiate more time off of care givers. These individuals developed stable feeding phenotypes that included being more efficient consumers during liquid intake trials, drinking more grams of diet per contact with the licksit. Conclusions : The weaning process appears to be particularly important in the development of feeding phenotypes and the development of juvenile obesity for the marmosets, and thus this is the time that should be focused upon for intervention testing in both nonhuman primates and children. 相似文献
369.
P P McCann C Tardif P S Mamont 《Biochemical and biophysical research communications》1977,75(4):948-954
Low concentrations of putrescine (10?5M) blocked ornithine decarboxylase (ODC) in rat hepatoma (HTC) cells in culture, but the lower homologue of putrescine, 1, 3 diaminopropane, had no effect on ornithine decarboxylase at 10?5M. Higher concentrations of both putrescine and 1, 3 diaminopropane induced approximately the same amount of soluble ODC antizyme type inhibitor. When concentrated dialyzed supernatants of cells grown in 10?5M putrescine were treated with 250 mM NaCl and chromatographed on a superfine Sephadex G-75 column, both ODC and inhibitor were recovered. Spermidine, spermine and cadaverine also induced the inhibitor suggesting a low specificity of induction by amines. 相似文献
370.
Julie Laplante Istvan Rajcan François J. Tardif 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(4):577-585
In weed species, resistance to herbicides inhibiting acetohydroxyacid synthase (AHAS) is often conferred by genetic mutations
at one of six codons in the AHAS gene. These mutations provide plants with various levels of resistance to different chemical classes of AHAS inhibitors.
Five green foxtail [Setaria viridis (L.) Beauv.] populations were reported in Ontario with potential resistance to the AHAS-inhibiting herbicide imazethapyr.
The objectives of this study were to confirm resistance, establish the resistance spectrum for each of the five populations,
and determine its genetic basis. Dose response curves were generated for whole plant growth and enzyme activity, and the AHAS gene was sequenced. Resistance was confirmed by determining the resistance factor to imazethapyr in the five resistant green
foxtail populations for whole plant dose response experiments (21- to 182-fold) and enzyme assays (15- to 260-fold). All five
imazethapyr-resistant populations showed cross-resistance to nicosulfuron and flucarbazone while only three populations had
cross-resistance to pyrithiobac. Sequence analyses revealed single base-pair mutations in the resistant populations of green
foxtail. These mutations were coded for Thr, Asn, or Ile substitution at Ser653. In addition, a new mutation was found in one population that coded for an Asp substitution at Gly654. There is an agreement between the spectra of resistance observed and the type of resistance known to be conferred by these
substitutions. Moreover, it indicates that, under similar selection pressure (imazethapyr), a variety of mutations can be
selected for different populations, making the resistance pattern difficult to predict from herbicide exposure history. 相似文献