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R P Erickson

Publications and source records attributed to R P Erickson.

At least 19 recordsLinked to original sources
PubMed1979

Enzyme changes associated with mitoichondrial malic enzyme deficiency in mice.

A genetically determined absence of mitochondrial malic enzyme (EC 1.1.1.40) in c3H/c6H mice is accompanied by a four-fold increase in liver glucose-6-phosphate dehydrogenase and a two-fold increase for 6-phosphogluconate dehydrogenase activity. Smaller increases in the activity of serine dehydratase and glutamic oxaloacetic transaminase are observed while the level of glutamic pyruvate transaminase activity is reduced in the liver of deficient mice. Unexpectedly, the level of activity of total malic enzyme in the livers of mitochondrial malic enzyme-deficient mice is increased approximately 50% compared to littermate controls. No similar increase in soluble malic enzyme activity is observed in heart of kidney tissue of mutant mice and the levels of total malic enzyme in these tissues are in accord with expected levels of activity in mitochondrial malic enzyme-deficient mice. The divergence in levels of enzyme activity between mutant and wild-type mice begins at 19--21 days of age. Immunoinactivation experiments with monospecific antisera to the soluble malic enzyme and glucose-6-phosphate dehydrogenase demonstrate that the activity increases represent increases in the amount of enzyme protein. The alterations are not consistent with a single hormonal response.

Aging↗
PubMed1979

Beat frequency is bimodally distributed in spermatozoa from T/t12 mice.

Flagellar beat frequencies of spermatozoa from mice of varying genotype were studied using highspeed cinemicrography. Beat frequency was variable but unimodal in two inbred lines, their F1, and an outbred line. In contrast, beat frequency in spermatozoa from T-complex, balanced lethal stocks (T/t6 and T/t12) tended not to vary between individual males of each genotype up to four hours after collection. The two-hour distribution of beat frequency for T/t12 was, moreover, bimodal, suggesting the possible existence of two subpopulations of spermatozoa.

Alleles↗
PubMed1979

Immunological studies of the sperm-specific phosphoglycerate kinase-2 of mice.

Antiserum was prepared to 500-fold purified PGK-2A from mouse testes. Depsite the apparent high purity of the immunizing antigen, double diffusion analyses showed two precipitin lines, one of which can be shown to correspond to PGK-2. An immunoabsorbent column of liver homogenate coupled to cyanogen bromid-activated Sepharose was used to remove the contaminating antibody. Both immuno-inactivation and double diffusion analyses demonstrated that the PGK-2 antigen appeared in testes between days 30 and 34 of postnatal development. The antisera prepared against highly purified PGK-2A did not disclose any immunological differences between PGK-2A, PGK-2B, and PGK-2C either by double diffusion analyses or quantitative immunoprecipitation. Antisera to PGK-2 did not inhibit in vitro fertilization of zona-free hamsters ova by mouse spermatozoa.

Animals↗
PubMed1979

H-2 and non-H-2 determined strain variation in palatal shelf and tongue adenosine 3':5' cyclic monophosphate: a possible role in the etiology of steroid-induced cleft palate.

The concentration of cAMP was measured in palatal shelves and tongues of 14.5-day old foetuses, 14.5-day old foetuses from steroid treated mothers, and 15.5-day old foetuses from four inbred lines of mice which represent the four possible combinations of two H-2 alleles and two residual genetic backgrounds. The incidence of spontaneous and steroid-induced cleft palate in these four strains was also determined. Analyses of variance of the cAMP data reveal that both the H-2 region and residual genetic background determine cAMP concentrations in both tissues and on both days of development. Similar analyses of cAMP concentrations after steroid treatments of the mother indicate that the interaction between H-2 and residual genetic background is significantly different in the injected than in the uninjected mice in both palatal shelves and tongues. The incidence of steroid-induced cleft palate parallels the palatal shelf concentration of cAMP before steroid treatment of the mother with one exception. These data suggest that a portion of the H-2 controlled component of susceptibility to steroid-induced cleft palate is mediated through alterations in the metabolism of cAMP.

Animals↗
PubMed1979

Concept of neuron types in gustation in the rat.

1. In taste neurophysiology, from Pfaffmann's (49, 50) pioneering work until the present, the possibility of types of neurons corresponding in some sense with the "primary" taste qualities of Henning (33) has been entertained: recently types of gustatory neurons in peripheral nerves have been established according to which of the four classical stimuli is the "best stimulus." However, considerable variation occurs in the response profiles within neurons classified as belonging to the same type. The purpose of this research is to determine, using mathematical techniques where appropriate, if the within-type variation is spurious or, instead, indicates the absence of a typology of taste neurons. The data used were counts of the spike discharges of 50 individual taste neurons in the nucleus of the solitary tract of the rat, evoked by 32 diverse chemical stimuli. 2. Using as input the matrix of Pearson r correlation coefficients calculated for the responses of all pairings of neurons to all stimuli, multidimensional scaling analysis revealed a two-dimensional space in which no clear groupings of neurons occurred. 3. In a hierarchical cluster analysis of the neuron response profile similarities, no evidence of grouping was found, suggesting a more-or-less continuous variation among neurons. 4. When the organization of the 32 stimuli utilized was studied by the same techniques, no clear evidence for stimulus types was found, although the possibility of two stimulus types--"sweet" and "nonsweet"--was raised. 5. Construction of a joint neuron-stimulus space supported a spatial model of taste neuron-stimulus interaction, while analysis of the number and pattern of high correlations among neurons--even after allowance for attenuation due to measurement error--failed to support the notion of types of taste neurons with identical response profiles. 6. Aspects of the logical role of types of neurons in gustatory coding were discussed, and the results and methods of the present investigation were related to classification schemes for neurons in general. Suggestions for a formal taxonomy of neurons were given. 7. It should be emphasized that the present study and conclusions are of second-order, CNS neurons, whereas the studies advocating the presence of neurons types were of peripheral neurons. Taken together, the implication to be drawn from these studies is that if neural types do exist in peripheral taste nerves, the typology is lost at the first synapse and is thus unavailable to the CNS for coding purposes, at least in the rat.

Animals↗
PubMed1978

Glycosaminoglycan accumulation with partial deficiency of beta-glucuronidase in the C3H strain of mice.

Young (60--80 days) mice of the low beta-glucuronidase strain, C3H/HeJ, showed no differences in hepatic levels of glycosaminoglycans (GAGs) when compared to the randombred, "normal" Swiss-Webster mice of the same age. However, by 12 months of age hepatic GAG is nearly twice as high in C3H/HeJ mice as in Swiss-Webster mice. Studies of beta-glucuronidase, beta-galactosidase, and N-acetyl-beta-glucosaminidase in four tissues of the two types of mice at the two ages revealed that glucuronidase was the only enzyme with lower activity in the C3H/HeJ strain.

Aging↗
PubMed1978

t-Alleles and the possibility of post-meiotic gene expression during mammalian spermatogenesis.

Although there is strong evidence for post-meiotic RNA synthesis during spermatogenesis, definitive proof of haploid gene transcription is lacking. Segregation distortion in t-allele-bearing males provides evidence for post-meiotic gene expression since delayed mating experiments argue strongly that there are similar numbers of qualitatively different spermatozoa in ejaculates of males carrying moderately distorting t-alleles. Such post-meiotic transcription may not be infrequent but the intercellular bridges connecting spermatids would usually maintain gametic equivalence.

Alleles↗
PubMed1977

A new variant mucolipidosis: biochemical investigations on two siblings.

Biochemical studies are presented on two siblings with some features of Mucolipidosis III, but with distinctive clinical findings. Levels of beta-galatosidase, alpha-mannosidase, beta-glucuronidase, N-acetyl-beta-glucosaminidase and alpha-fucosidase found in serum from these patients ranged from 10 to 10 times higher than normal. The ratio of heat stable to heat labile serum isoenzymes of N-acetyl-beta-glucosaminidase is considerably greater than normal. An extremely low activity of beta-galactosidase was found in fibroblasts cultured from one patient. Levels of the remaining enzymes were in the low normal range. Similarly, beta-galactosidase levels were low in heart, kidney, liver, spleen and lung of one patient who died during the course of the study. Activities of the remaining enzymes were close to normal. No excessive excretion of mucopolysaccharide was noted, however, changes in distribution of several fractions were found. Mucopolysaccharide labeled with radioactive sulfate was degraded by cultured fibroblasts at a normal rate. In addition to clinical differences, the biochemical studies further demonstrate the uniqueness of these patients.

Acetylglucosaminidase↗
PubMed1977

Odorant responses in taste neurons of the rat NTS.

In the experiment reported in this paper, 22 of 35 neurons in the gustatory NTS were found to respond to odorant as well as taste stimuli. This odorant response was apparently mediated by the ethmoid nerve and at least one other odorant-responsive system, possibly other nasal trigeminal afferents. These gustatory neurons responded to odorants, as they did to taste stimuli, in a manner consistent with an encoding of stimulus quality information. Thus at least some of the neurons of the gustatory NTS carry information concerning several of the senses involved in ingestion.

Acetone↗