Showing papers by "Michigan State University published in 1974"
TL;DR: Evidence suggests that differential invertebrate colonization of leaf packs is a function of microbial colonization and conditioning, and significant differences between fall and winter processing and between the two sites are not.
Abstract: Summary
Detritus processing by a small woodland stream is analysed by following the loss of weight of 10 g, single species accumulations of riparian leaves. The daily loss rates are expressed as exponential coefficients after the data are fitted by least squares. Comparisons are made between two sites on a small hardwater trout stream during two seasons. Leaf processing rates form a continuum from a low of 0.5%/day to a high of 2.0%/day. Differences between species of leaf are observed, but significant differences between fall and winter processing and between the two sites are not.
The response of the invertebrate community to differences in leaf species is investigated using controlled, artificial streams where significant differences in the effect of the invertebrates are related to the ability ofthe leaf to be processed. Evidence suggests that differential invertebrate colonization of leaf packs is a function of microbial colonization and conditioning. The data are used to develop a general scheme of leaf pack processing.
1,272 citations
TL;DR: The poly(A) tract found in eukaryotic mRNA was used to study methylation in mRNA obtained from Novikoff hepatoma cells, demonstrating a unique distribution of methylated nucleosides in mRNA.
Abstract: The poly(A) tract found in eukaryotic mRNA was used to study methylation in mRNA obtained from Novikoff hepatoma cells. Methyl labeling of RNA was achieved with L-[methyl-3H]methionine under conditions that suppress radioactive incorporation into the purine ring. RNA that contains a poly(A) segment was obtained from polysomal RNA by chromatography on oligo(dT)-cellulose. Sucrose density gradient centrifugation of this RNA revealed a pattern expected for mRNA. The composition of the methyl-labeled nucleosides in the RNA was analyzed after complete enzymatic degradation to nucleosides. By use of DEAE-cellulose (borate) chromatography, which separates 2′-O-methylnucleosides from normal and base-methylated nucleosides, about 50% of the radioactivity was recovered in the 2′-O-methylnucleoside fraction and 50% in the base-methylnucleoside fraction. High-speed liquid chromatography (Aminex A-5) of the 2′-O-methylnucleoside fraction produced four peaks coincident with the four 2′-O-methylnucleoside standards. Analysis of the base-methylnucleoside fraction revealed a unique pattern. While ribosomal RNA and tRNA possessed complex base-methylnucleoside patterns, the distribution in mRNA was quite simple, consisting predominantly of N6-methyladenosine. These results demonstrate a unique distribution of methylated nucleosides in mRNA. By analogy to ribosomal RNA synthesis, the presence of methylnucleosides in mRNA may reflect a cellular mechanism for the selective processing of certain mRNA sequences.
1,229 citations
TL;DR: It is suggested that paraquat toxicity may be mediated through the transfer of a single electron from reduced paraqu at to oxygen and thus form superoxide ion.
532 citations
TL;DR: The photosynthetic assimilates in leaves of Perilla crispa attached to the plant were labeled by treating the leaves with (14)CO(2), and it was concluded that the radioactive products in the solution are actually exuded by the phloem.
Abstract: The photosynthetic assimilates in leaves of Perilla crispa attached to the plant were labeled by treating the leaves with 14 CO 2 . When subsequently detached, these leaves exuded a negligible amount of radioactivity from the cut petiole into water. Ethylenediaminetetraacetate (EDTA), citric acid, and ethyleneglycol-bis (β-aminoethyl ether) N , N ′-tetraacetate greatly increased exudation of labeled assimilates into a solution bathing the petioles. The optimal concentration of EDTA was 20 mm, and maximal exudation took place between 2 and 4 hours after excision. Up to 22% of the radioactivity fixed in the leaf was exuded into an EDTA solution as compared to an export of 38% from attached leaves. The amount of radioactivity in the exudate was much reduced at low temperature. Presence of EDTA was required in the collecting solution for only 1 to 2 hours; upon transfer to water, exudation continued as in continuous presence of EDTA. Ca 2+ completely inhibited the effect of EDTA. Anatomical studies indicated that callose formation on the sieve plates near the cut surface of the petioles was less in leaves on EDTA than on water. More than 95% of the radioactivity exuded by detached leaves was present in the sugars verbascose, stachyose, raffinose, and sucrose, which are translocated in the phloem of Perilla. Labeled glucose, fructose, and galactinol were detected in the leaf blade and petiole, but not in exudates. The addition of EDTA to a solution bathing the petiole of detached leaves of Chenopodium rubrum and Pharbitis nil also increased the exudation of labeled assimilates. In these two species, label appeared only in a compound that cochromatographed with sucrose. It is concluded that the radioactive products in the solution are actually exuded by the phloem. Possibly EDTA chelates Ca 2+ that otherwise participates in the reactions that seal cut phloem.
434 citations
TL;DR: In this paper, a tensor integral equation for the electric field inside the body was derived and solved numerically for various biological models, and a theoretical method was developed to determine the electromagnetic field induced inside heterogeneous biological bodies of irregular shapes.
Abstract: A theoretical method has been developed to determine the electromagnetic field induced inside heterogeneous biological bodies of irregular shapes. A tensor integral equation for the electric field inside the body was derived and solved numerically for various biological models.
406 citations
TL;DR: In this article, the authors test the view that organization structure and process are related to organizational climate which in turn is related to organization performance and employee job satisfaction, and find that several organizational process variables (but no structural variables) were significantly related to the climate of the organization as perceived by scientists.
270 citations
246 citations
TL;DR: Investigation of cucumber accessions from 41 nations found incorporation of an allelopathic character into a crop cultivar could provide the plant with a means of gaining a competitive advantage over certain weeds.
Abstract: Cucumber (Cucumis sativus L.) accessions from 41 nations were grown with two indicator species in a search for superior competitors. Of the plant introductions tested, one inhibited indicator plant growth by 87 percent and 25 inhibited growth by 50 percent or more. The toxicity of leachates from pots containing inhibitory cucumbers to indicator plants germinated in separate containers suggested allelopathy. Incorporation of an allelopathic character into a crop cultivar could provide the plant with a means of gaining a competitive advantage over certain weeds.
240 citations
TL;DR: It is concluded that the GA(3)-dependent increase in phosphorylcholine glyceride transferase activity (which occurs within the first 4 hours ofGA(3) treatment) does not require RNA synthesis or protein synthesis.
Abstract: Cell-free extracts from gibberellic acid-treated barley (Hordeum vulgare L. cv. Himalaya) aleurone layers show phosphorylcholine glyceride transferase activity greater than that from control layers. The increase in activity is not prevented by a mixture of amino acid analogs nor by cordycepin under conditions in which it is demonstrated that the analogs and the cordycepin are entering the cells in effective concentrations. We conclude therefore that the GA3-dependent increase in phosphorylcholine glyceride transferase activity (which occurs within the first 4 hours of GA3 treatment) does not require RNA synthesis or protein synthesis.
232 citations
TL;DR: In this paper, a study of the relationship between partisan preference and social integration in natural work groups in several automobile plants was conducted, showing that the number of work group friends increases from the Democratic to the Republican end of a standard party identification scale.
Abstract: This is a study of the relationship between partisan preference and social integration in natural work groups in several automobile plants. The basic finding is that the number of work group friends increases from the Democratic to the Republican end of a standard party identification scale. Since the political context of the study sample is heavily Democratic, attention is focused on the fact that Republicans in this environment are political deviants. It is suggested that friendship integration is a function of perceived deviance in that deviating from group norms leads to social insecurity, cognitive dissonance, and a need for opinion evaluation, all of which motivate affiliative behavior. Several hypotheses are deduced from this proposition. The first is that Republicans have less political contact in nonwork contexts, but more in the work group, than Democrats do. Second, the relationship between partisanship and friendship integration should be greater for members of social groups in which the pro-Democratic norm is stronger than for those in which this norm is weaker. Third, strength of identification with the norm-bearing group ought to be positively related to friendship integration among deviants, since identification would make the group's norms more salient and increase the deviant's discomfort. Fourth, political deviants should tend to choose each other as friends to a greater extent than political conformers do. Finally, since friendship alliances apparently serve a protective function for political deviants, it is hypothesized that among deviants (but not among conformers), friendship integration should be related to political participation. All the hypotheses are supported. The results are interpreted in terms of the critical function of social support for political deviants in pluralist societies. Since pressures for conformity are strong, it is important to understand the ways in which minorities deal with them. Friendships in work groups, ostensibly nonpolitical, therefore have important political functions.
208 citations
TL;DR: When tested for masculine sexual behavior 7, 10 and 13 days after the start of steroid treatment, animals receiving testosterone applications in the POA exhibited significantly more mounts, intromissions and ejaculations than the animals receivingosterone in the PHA or cholesterol in the preoptic area.
Abstract: Intracerebral applications of cholesterol, testosterone or estradiol were evaluated as to their ability to induce masculine sexual behavior in long-term castrated male rats. Thirty castrated male rats that had exhibited no ejaculatory response in three consecutive weekly tests were bilaterally implanted with stainless steel cannulae in the preoptic area (POA) (20 animals) or in the posterior hypothalamic area (PHA) (10 animals). The animals implanted with cannulae in the PHA and 10 animals implanted in the POA received applications of testosterone (15 µg/cannula every 3 days) for 12 days. The 10 remaining animals with cannulae placed in the POA received cholesterol applications (15 µg/cannula every 3 days) for 12 days. When tested for masculine sexual behavior 7, 10 and 13 days after the start of steroid treatment, animals receiving testosterone applications in the POA exhibited significantly more mounts, intromissions and ejaculations than the animals receiving testosterone in the PHA or cholesterol in t...
TL;DR: A problem of current concern to the behavioral scientist is race and sex group discrimination in employment hiring as mentioned in this paper, and a number of articles have appeared that discuss methodological considerations releva-...
Abstract: A problem of current concern to the behavioral scientist is race and sex group discrimination in employment hiring. Numerous articles have appeared that discuss methodological considerations releva...
TL;DR: It is demonstrated that the antibody binds preferentially to the liver microsomes isolated from phenobarbital-pretreated rats, in which the 45,000-dalton hemoprotein has been shown to be induced.
TL;DR: In this paper, the authors examine from a theoretical standpoint the process of rural-urban migration in Africa and its role in economic development with a view toward proposing a research agenda to address key policy issues.
Abstract: It is the aim of this paper to examine from a theoretical standpoint the process of rural-urban migration in Africa and its role in economic development with a view toward proposing a research agenda to address key policy issues. We do this in three stages. First the large body of theoretical and empirical knowledge of the rural-urban migration process in Africa is briefly reviewed emphasising those characteristics which are most important in Africa and the deficiencies in our present understanding of rural-urban migration. Second this knowledge is synthesized into a theoretical framework for analyzing rural-urban migration with emphasis on economic variables. This framework is then used to explore some of the policy implications of present-day rural-urban migration for economic development in Africa. Finally priority areas for future migration research are discussed with particular reference to improve theory improved methodology and the integration of migration research and policy analysis. (excerpt)
TL;DR: In comparison to controls, copper‐deficient suckling rats showed an appreciable decrease in body growth, a slight decrease in whole brain and cerebellar growth, and a highly significant decrease in myelination based on the activity of Cerebellar 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase—a myelin enriched protein.
Abstract: — In comparison to controls, copper-deficient suckling rats showed an appreciable decrease in body growth, a slight decrease in whole brain and cerebellar growth, and a highly significant decrease in myelination based on the activity of cerebellar 2′,3′-cyclic nucleotide 3′-phosphohydrolase—a myelin enriched protein. Specific effects of a fivefold reduction in the copper content of brain were seen in a drastic decrease in cerebellar cytochrome c oxidase and smaller but significant drops in cerebellar super-oxide dismutase and brain norepinephrine concn. These observations are discussed with respect to the neuropathology and biochemistry of Menkes’ steely-hair disease, a sex-linked recessive disorder in humans characterized by copper deficiency.
TL;DR: The limiting sizes of molecules that can permeate the intact cell wall and protoplast membrane of Saccharomyces cerevisiae were determined from the inflection points in a triphasic pattern of passive equilibrium uptake values obtained with a series of inert probing molecules varying in molecular size.
Abstract: The limiting sizes of molecules that can permeate the intact cell wall and protoplast membrane of Saccharomyces cerevisiae were determined from the inflection points in a triphasic pattern of passive equilibrium uptake values obtained with a series of inert probing molecules varying in molecular size. In the phase identified with the yeast protoplast, the uptake-exclusion threshold corresponded to a monodisperse ethylene glycol of molecular weight = 110 and Einstein-Stokes hydrodynamic radius (rES) = 0.42 nm. In the cell wall phase, the threshold corresponded to a polydisperse polyethylene glycol of number-average molecular weight (¯Mn) = 620 and average radius (rES) = 0.81 nm. The third phase corresponded to complete exclusion of larger molecules. The assessment of cell wall porosity was confirmed by use of a second method involving analytical gel chromatographic analyses of the molecular weight distribution for a single polydisperse polyglycol before and after uptake by the cells, which indicated a quasi-monodisperse threshold for the cell wall of Mn = 760 and rES = 0.89 nm. The results were reconciled with two situations in which much larger protein molecules previously have been reported able to penetrate the yeast cell wall.
TL;DR: In this paper, a study was conducted to further elucidate the functional properties of whey protein with respect to foaming and emulsifying capacities and observe the effect of enzymatic hydrolysis on these properties.
Abstract: A study was undertaken to further elucidate the functional properties of whey protein with respect to foaming and emulsifying capacities and to observe the effect of enzymatic hydrolysis on these properties. Emulsion capacity decreased as proteolysis continued suggesting there is an optimum mean molecular size of the proteins involved which is lower than that of casein. Heat treatment of the reconstituted protein concentrate was necessary for foam stability; specific volume and foam stability increased directly with temperature of heating. Re effect of pH on whippability, data indicate that the greater the net charge the greater the tendency to foam. A limited amount of hydrolysis appears desirable to increase foaming but greatly decreases foam stability.
TL;DR: In this paper, the relationship between influence methods of project managers and their project performance was investigated and it was found that influence methods emphasizing work challenge and expertise are more effective than others.
Abstract: The relationships between influence methods of project managers and their project performance are investigated. Findings indicate that influence methods emphasizing work challenge and expertise are...
TL;DR: GnRH induced LH release and ovulation and these cows continued to cycle to Day 65 postpartum when the study was terminated and GnRH did not shorten the interval to first estrus.
Abstract: Ovulation estrous and endocrine response after the administration of gonadotropin-releasing hormone (GnRH) were studied in 20 lactating cows. The cows received either a (100 GnRH mcg) SUBCUTANEOUS implant or saline on Day 14 postpartum. Serum luteinizing hormone (LH) increased (p less than .05) from 1.9 ng/ml at GnRH administration to 5.7 13.8 and 15 at 1 2 and 4 hours and decreased to 4.7 ng/ml at 6 hours. All cows who received GnRH ovulated on Day 15. The interval to the first postpartum ovulation was shorter (14.4 days; p less than .05) for GnRH-treated cows than for 8 of 10 controls (23.6 days). Estrogens and progesterone were not acutely affected by GnRH. GnRH did not shorten the interval to first estrus. GnRH induced LH release and ovulation and these cows continued to cycle to Day 65 postpartum when the study was terminated.
01 Jan 1974
TL;DR: Testosterone not only sustains male sexual behavior in castrated male rats and induces male sexual responses in the female but also increases female responses, and estrogen facilitates sexual receptivity in both males and females.
Abstract: Testosterone not only sustains male sexual behavior in castrated male rats and induces male sexual responses in the female but also increases female responses (Whalen and Hardy, 1970; Pfaff, 1970). Similarly, estrogen facilitates sexual receptivity in both males and females and increases male sexual behavior in the gonadectomized rat (Pfaff, 1970).
TL;DR: Group N streptococci possess enzymes for the metabolism of d-Galactose through both the d-galactose 1-phosphate pathway (Leloir pathway) and thed-tagatose 6-ph phosphate pathway.
Abstract: Group N streptococci possess enzymes for the metabolism of d-galactose through both the d-galactose 1-phosphate pathway (Leloir pathway) and the d-tagatose 6-phosphate pathway.
TL;DR: In this paper, the effect of diet on the activity of enzymes involved in fatty acid and cholesterol synthesis is discussed. But, the authors do not consider the effects of dietary manipulations on liver and adipose tissue.
Abstract: Publisher Summary This chapter discusses the effect of diet on activity of enzymes involved in fatty acid and cholesterol synthesis. Adipose tissue is the major organ contributing to de novo fatty acid synthesis in the nonlactating pig and ruminant, while the liver is more important in birds and man. In rats and mice, both organs contribute significantly to de novo fatty acid synthesis. In species such as the rat, where both liver and adipose tissue contribute to de novo fatty acid synthesis, dietary manipulations generally affect both tissues in a similar fashion; however, there are exceptions. The quantity of hepatic fatty acid synthetase can regulate the rate of fatty acid synthesis in rats fed high-carbohydrate diets. Unlike enzymes involved in fatty acid synthesis, a change in β -Hydroxy- β -methylglutaryl-CoA reductase activity precedes changes in hepatic acetate conversion to cholesterol. Allosteric control of enzyme activity plays a major role in the rapid regulation of metabolic flux. Adaptive changes in enzyme content reflect sustained changes in metabolic flux and such adaptations are involved in the longer term regulation of metabolism.
TL;DR: 1 l -myo-inositol 1-phosphatase from rat mammary tissue appears to exist in a native tetrameric form of 210,000 as determined by gel filtration which, upon heating at 70 °C for 15 min, is converted into a stable monomer of approximately 52,000.
TL;DR: A behavioral mechanism is involved in this reproductive delay in siblings experimentally paired before puberty, since prepubertal familiarity also delays reproduction in nonsibling pairs, which may act to reduce inbreeding depression and regulate population growth.
Abstract: Sibling mating in prairie deer mice (Peromyscus maniculatus bairdi) results in poor reproductive performance. Siblings experimentally paired before puberty exhibit delayed reproduction when adult. A behavioral mechanism is involved in this reproductive delay, since prepubertal familiarity also delays reproduction in nonsibling pairs. Such a reproductive delay may act to reduce inbreeding depression and regulate population growth.
TL;DR: Application of an isotope-dilution method to seedlings of Avena sativa and Zea mays indicates the upper limit of free indole-3-acetic acid in Avena to be about 16 mug per kg and in Zea, about 24 mug.
Abstract: An isotope-dilution method has been developed for the assay of free indole-3-acetic acid and ester indole-3-acetic acid as measured by indole-3-acetic acid liberated by mild alkaline hydrolysis Application of this method to seedlings of Avena sativa and Zea mays indicates the upper limit of free indole-3-acetic acid in Avena to be about 16 μg per kg and in Zea, about 24 μg The amount of 1 n alkali-labile indole-3-acetic acid in Zea is about 330 μg per kg and there is very little 1 n alkali-labile IAA in Avena A chemical characterization of the indole-3-acetic acid of Avena and a confirmation of the chemical characterization of the indole-3-acetic acid of Zea is presented