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PubMed1983

Effect of developmental stage of explants on further in-vitro development of hamster molars.

With morphometrical and biochemical methods the in-vitro development of 1-4-day-old 2nd maxillary molars was studied up to 10 days and compared with previously reported in-vivo development. Incorporation of [3H]-thymidine and increase in dry weight were used as biochemical parameters for cell proliferation and growth respectively specific alkaline phosphatase activity and uptake of 45Ca as the measure for mineralization. In explants of 2-4-day-old hamsters, formation of dentine and enamel matrix was consistent: both mineralized. These explants attained stages beyond enamel matrix formation, possibly the transitional stages of amelogenesis. The amounts of matrices produced appeared to be related to the final size the explants attained. Best in-vitro development histologically was in explants of 2 and 3-day-olds. Thus in-vitro development was qualitatively similar to in vivo.

Alkaline Phosphatase↗
PubMed1980

The dependency of proton extrusion in the light on the developmental stage of the photosynthetic apparatus in Rhodospirillum rubrum.

The rate of proton extrusion by whole cells of Rhodospirillum rubrum is constant on a bacteriochlorophyll basis only above cellular bacteriochlorophyll concentrations of about 10 nmol bacteriochlorophyll per mg cell protein. At specific bacteriochlorophyll cellular levels below this value, the rate of proton extrusion per bacteriochlorophyll increases. Correspondingly, membrane preparations isolated from these cells exhibit increases in the rate of proton uptake on a pigment basis. Concomitant with variations in the rates of proton extrusion by whole cells, light energy fluxes for saturating this process also vary. A fair proportionality between maximum rates of proton extrusion of whole cells and the bacteriochlorophyll cellular levels above 10 nmol per mg protein indicates that the degree of continuity of intracytoplasmic membranes and of the cytoplasmic membrane remains largely constant.

Bacteriochlorophylls↗
PubMed1974

Single-stranded regions in DNA isolated from different developmental stages of the sea urchin.

Long-term labeled sea urchin embryo (Strongylocentrotus purpuratus) DNAs were examined for size of recovered pieces, single-strandedness, and length of continuous double-stranded regions. Sizing on neutral sucrose gradients indicates that morula stage DNA sediments predominantly at 31 S, blastula stage DNA at 27 S, and gastrula stage DNA as a broad range of sizes of greater than 29 S. Treatment of [3H]thymidine-labeled DNA with Aspergillus oryzae S1 nuclease removes 19% of the 3H from morula stage DNA, 4% of the 3H from blastula stage DNA, and less than 0.1% of the 3H from gastrula stage DNA. Sedimentation of S1 nuclease treated [3H]DNAs on alkaline sucrose gradients indicates that in native morula stage DNA there is a nick or gap in one strand approximately every 9700 base pairs, in native blastula stage DNA about every 3300 base pairs, and very few nicks or gaps in native gastrula stage DNA.

Animals↗
PubMed1978

Quantitative analysis of RNA, glycogen and nucleotides from different developmental stages of Ascaris lumbricoides (var. suum).

Cold acid phenol extractions (Kirby, K.S. (1968) in Methods in Enzymology, Vol. XII B, pp. 87--99, Academic Press, New York) of homogenates from oocytes, zygotes and larval stages of Ascaris lumbricoides yield predominantly glycogen, some glycogen . phosphate complexes and guanine nucleotides, but only small amounts of RNA. Oocytes contain 10.0 pg of extractable 19 S and 26 S rRNA and 1.1 pg 4 S and 5 S RNA per cell. During the maturation of the oocyte to the zygote stage, the amount of 19 S and 26 S rRNA increases by 57%, and that of 4 S and 5 S RNA by 130%. Larval stages contain 62% more 19 S and 26 S rRNA, and 47% more 4 S and 5 S RNA than zygotes. The amount of the extractable glycogen decreases by about 80% and nucleotides by about 70% from oogenesis to the larval stage. The Kirby extract from homogenates of spermatids contains only traces of glycogen, glycogen . phosphate complexes and nucleotides, and 115 times less RNA per spermatid than oocytes. The nucleotide pool sizes of oocytes, zygotes and larval stages were determined; the pools consist of 71--88% guanine nucleotides. Spermatids contain only adenine nucleotides and an unidentified, nucleotide-like compound.

Animals↗
PubMed1990

Retinoic acid receptor in the chick limb buds in the early developmental stages.

Two retinoic acid-binding proteins, a high molecular weight one (90-100 kDa) (peak A) and CRABP (peak B), were obtained on gel filtration column chromatography of extracts of limb buds of chick embryos. The presence of a retinoic acid receptor (RAR) (45 kDa) and the absence of chick-CRABP type II (16.2 kDa) in the peak A fractions suggested that the 45 kDa RAR forms a homo- or hetero-dimeric structure (90-100 kDa) with other RARs or other nuclear proteins, but not with chick-CRABP type II, in the limb buds of chick embryos. We also demonstrated that there were no significant differences in the amount of RAR in the anterior, middle and posterior parts of limb buds (stages 23-25).

Animals↗
PubMed1983

Comparison of cytochrome P-450-dependent metabolism in different developmental stages of Drosophila melanogaster.

The activities of several drug metabolizing enzymes were compared in microsomes from larvae and adult Drosophila. The cytochrome P-450 content and the benzo[a]pyrene (BP) hydroxylation, p-nitroanisole demethylation and 3- and 4-hydroxylation of biphenyl were 4-20-fold higher in microsomes from adult flies, while 7-ethoxycoumarin deethylase activity and cytochrome c reductase activity were about the same in the two stages. 2-OH-biphenyl was formed in trace amounts by microsomes from adult flies but not to any detectable amount by microsomes from larvae. Pretreatment with phenobarbital (PB), Aroclor 1254 (PCB) or beta-naphthoflavone (BNF) increased the cytochrome P-450 content and the various cytochrome P-450-mediated reactions up to 7-fold in larvae. The effects of the pretreatments were weaker in adult flies, where the increase never was more than 3-fold, and many reactions were unaffected by the pretreatments. BNF was thus inefficient in enhancing all reactions, except a slight (1.3-fold) increase in the formation of 4-OH-biphenyl. Microsomes from both stages exhibited increases in specific protein bands with apparent molecular weights of 51 000-58 000 in the sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis following treatment with PB, PCB and BNF. Differences were observed between larvae and adults with respect both to the number of and the molecular weights of the increased protein bands.

Animals↗