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W H Klein

Publications and source records attributed to W H Klein.

At least 91 records · Page 5Linked to original sources
PubMed1978

Characteristics of individual repetitive sequence families in the sea urchin genome studied with cloned repeats.

Cloned repetitive sequences from the S. purpuratus genome a few hundred to approximately 1000 nucleotides long were used to investigate the characteristics of individual repetitive sequence families. They wer terminally labeled by the kinase procedure and reacted with sheared S. purpuratus DNA. Repetition frequencies were measured for 26 individual families and were found to vary from a few to several thousand copies per genome. Estimates of sequence divergence were made for 18 cloned repeat families by measuring thermal stability of the heteroduplexes formed between the genomic DNA and the cloned fragments, compared with that of the renatured cloned fragments. The difference was less than 4 degrees C for three of the 18 families, and less than 10 degress C for 13 of the 18 families. These 13 repetitive sequence families lack any detectable highly divergent sequence relatives, and the results reported are shown not to change when the renaturation criterion is lowered below 55 degrees C in 0.18 M Na+. Five of the 18 cloned families displayed greater sequence divergence. The average sequence divergence of the total short repetitive sequence fraction of S. purpuratus DNA was found to match closely the average of the divergences of the cloned repeat sequences.

Base Sequence↗
PubMed1976

Structural gene sets active in embryos and adult tissues of the sea urchin.

Structural gene sequences active in a variety of sea urchin adult and embryo tissues are compared. A single-copy 3H-DNA fraction, termed mDNA, was isolated, which contains sequences complementary to the messenger RNA present on gastrula stage polysomes. Gastrula message sequences are 50 fold concentrated in the mDNA compared to total single-copy DNA. mDNA reactions were carried out with excess mRNA from blastula, pluteus, exogastrula, adult ovary, tubefoot, intestine, and coelomocytes, and with excess total mature oocyte RNA. A single-copy 3H-DNA fraction totally devoid of gastrula message sequences, termed null mDNA, was also reacted with these RNAs. Large differences in the extent of both mDNA and null mDNA reaction with the various RNAs were observed, indicating that in each state of differention a distinct set of structural genes is active, generally characterized by several thousand specific sequences. The complexity of gastrula mRNA was shown in previous work to be about 17 X 10(6) nucleotides. In units of 10(6) nucleotides, the complexities of the RNA sequence reacting with mDNA and with null mDNA in each tissue are, respectively, as follows: intestine mRNA: 2.1 and 3.7; coelomocyte mRNA: 3.5 and less than or equal to 1.4; tubefoot mRNA: 2.7 and less than or equal to 0.4; ovary mRNA: 13 and 6.7; oocyte total RNA: 17 and 20; blastula mRNA: 12 and 15; pluteus mRNA: 14 and less than or equal to 0.6; exogastrula mRNA: 14 and less than or equal to 0.6. The total complexity of each mRNA polulation is the sum of these values, as verified for several cases by reactions with total single-copy DNA. A relatively small set of mRNAs, the complexity of which is about 2.1 X 10(6) nucleotides, appears to be shared by several of the tissues studied.

Animals↗
PubMed1975

Structural genes adjacent to interspersed repetitive DNA sequences.

The observation that repetitive and single copy sequences are interspersed in animal DNAs has suggested that repetitive sequences are adjacent to single copy structural gene sequences. To test this concept, single copy DNA sequences contiguous to interspersed repetitive sequences were prepared from sea urchin DNA by hydroxyapatite fractionation (repeat-contiguous DNA fraction). These single copy sequences included about one third of the total nonrepetitive sequence in the genome as determined by the amounts recovered during the hydroxyapatite fractionation and by reassociation kinetics. 3H-labeled mRNA from sea urchin gastrula was prepared by puromycin release from polysomes and used in DNA-driven hybridization reactions. The kinetics of mRNA hybridization reactions with excess whole DNA were carefully measured, and the rate of hybridization was found to be 3-5 times slower than the corresponding single copy DNA driver reassociation rate. The mRNA hybridized with excess repeat-contiguous DNA with similar kinetics relative to the driver DNA. At completion 80 percent of that mRNA hybridizable with whole DNA (approximately 65 percent) had reacted with the repeat-contiguous DNA fraction (50 percent). This result shows that 80-100 percent of the mRNA molecules present in sea urchin embryos are transcribed from single copy DNA sequences adjacent to interspersed repetitive sequences in the genome.

Animals↗
PubMed1974

Distribution of repetitive and nonrepetivite sequence transcripts in HeLa mRNA.

Polyadenylated messenger RNA extracted from HeLa cells was hybridized with a mass excess of HeLa DNA. The kinetics of the hybridization reaction demonstrated that most of the messenger RNA is transcribed from nonrepetitive DNA. The amount of messenger RNA hybridized to DNA was measured both with and without prior RNase treatment. Comparison of the results indicates that within the limits of detection, HeLa messenger RNA does not contain repetitive sequence elements covalently linked to nonrepetitive sequence transcripts. However, a small fraction of the HeLa messenger RNA preparation is transcribed entirely from repetitive DNA sequences. This fraction represents about 6% of the total polyadenylated messenger RNA preparation.

Adenosine↗
PubMed1971

Photomorphogenesis in Arabidopsis thaliana (L.) Heynh: Threshold Intensities and Blue-Far-red Synergism in Floral Induction.

Arabidopsis seeds were germinated on sterile mineral agar supplemented with 1% glucose and cultured under continuous light regimes. With 4-hour incandescent plus 20-hour monochromatic illumination in the region from 400 to 485 nanometers there was effective floral induction at an intensity of 100 microwatts per square centimeter. Exclusion of far red wave lengths from the 4-hour incandescent period sharply reduced the effectiveness of subsequent monochromatic blue light in promoting floral induction. Delayed floral induction occurred under continuous incandescent light lacking far red and was attributable to the blue wave lengths. Continuous 485 nanometer (100 microwatts per square centimeter) exposure without any white light treatment during the postgermination growth period was ineffective in floral induction and meristem development. Light at 730 nanometers under the same conditions was partially effective, whereas energy between 500 and 700 nanometers was completely ineffective. When continuous monochromatic light at a 3-fold higher energy level was administered, all photomorphogenic responses were accomplished with 485 nanometer light, including germination and 100% floral induction without any white light treatment at any time during the experiment. Almost equal quantum effectiveness was calculated when equivalent quantum flux densities in the region from 710 to 740 nanometers or at 485 nanometers were used. It is postulated that floral induction in Arabidopsis may be the result of a continuous excitation of a stable form of far red-absorbing phytochrome localized in or on a membrane, and that excitation can be either by direct absorption of energy by far red-absorbing phytochrome or by transfer from an accessory pigment.

Journal Article↗
PubMed1967

Spectrophotometric Measurements of Phytochrome in vivo and Their Correlation with Photomorphogenic Responses of Phaseolus.

Direct in vivo measurements of phytochrome have been made in Phaseolus vulgaris by 2-filter difference spectrophotometry (Ratiospect). All measurements were made at 730 versus 800 nm and it is assumed that the Delta (DeltaOD) is directly proportional to the PFR concentration of phytochrome present. Dose response curves were determined for both physiological and spectrophotometric responses for red induction and far-red photoinactivation. For induction, saturation occurs at 100 mj/cm(2) and for inactivation at 30 mj/cm(2). The rate of hook opening and the physiological response measured 20 hours after induction are both shown to be directly proportional to the initial amount of PFR present spectrophotometrically. The sensitivity of the tissue correlates well with the absolute amount of phytochrome present, the inner portion of the hook having the maximum concentration of 0.042 Delta (DeltaOD)/g fresh weight. If the total reversible phytochrome concentration is reduced by exposure to red light and allowing PFR to decay out of the system the remaining sensitivity of the tissue is shown to be directly correlated with the amount of PR remaining in the tissue. PFR disappears rapidly in the dark at 25 degrees , and is not detectable after 6 hours. There is no indication that PFR reverts in the system to PR. At 4 degrees , PFR does not disappear measurably up to 1 hour and is nearly totally reversible to PR.

Journal Article↗