A Proposed Heuristic for Communicating Heritability Estimates to the General Public, with Obesity as an Example

It is well established that many continuously distributed traits have a heritable component. However, it is often difficult to communicate to the general public the meaning of quantitative estimates of heritability. To address this problem, the present paper introduces a heuristic for communicating heritability to nonscientific audiences. This heuristic involves adopting an extremely simplified model of inheritance and artificially (and somewhat arbitrarily) defining a cutoffs of low environmental risk and affectation status. Using body weight and obesity as an example, we present a table which gives estimates of the proportion of obese persons who are genetically obese assuming varying levels of environmental risk for obesity and relative body weight scores for defining obesity. The resulting statistic may prove useful for lay audiences in understanding a heritability estimate.     

Synergistic effects of tumour necrosis factor-α and interferon-γ on feline haemopoietic progenitors

Pathogenic mechanisms that underlie feline leukaemia virus subgroup-C (FeLV-C) induced erythroid aplasia are unknown. FeLV-C infection is associated with higher serum levels of interferon- (IFN-) and tumour necrosis factor- (TNF-), which may act synergistically to cause haemopoietic suppression. In the present studies, the synergistic effects of TNF- and IFN- on feline bone marrow progenitors in vitro were evaluated. Bone marrow mononuclear cells from specific-pathogen-free cats were exposed to TNF- (100 and 200 pg/ml) and IFN- (100 or 200 units/ml), alone or in combination, for 2 h before plating for clonal assays of colony forming units. Our results show that TNF- and IFN- in combination caused marked suppression of feline colony forming units-erythroid (CFU-E), burst forming units-erythroid (BFU-E), and colony forming units-fibroblasts (CFU-F), whereas colony forming units-granulocyte/macrophage (CFU-GM) were minimally affected. The same concentrations of TNF- and IFN- alone had minimal effects on CFU-E, BFU-E and CFU-F. These results suggest that TNF- and IFN- may play a significant role in regulating haemopoiesis in cats and may be involved in the pathogenesis of erythroid aplasia in cats infected with feline leukaemia virus.     

Identification and quantitation of cortisol metabolites in rat liver homogenate and -slices

Summary Cortisol-1, 2-H³ was incubated with rat liver homogenate and/or rat liver slices in the presence of a NADPH-generating system. The following metabolites could be identified in adult male rats: -cortol, allo--cortol, 3-allo--cortol, 20-hydroxy-cortisol, 11, 17, 20, 21-tetrahydroxy-5-pregnan-3-one, 3-allotetrahydrocortisol, tetrahydrocortisol, trace amounts of allotetrahydrocortisol and two highly polar metabolites only partly identified. In female rats only tetrahydrocortisol, allotetrahydrocortisol and allodihydrocortisol could be detected in significant amounts.The radioactive metabolites mentioned above were localized and quantitated on paper chromatograms by a 4-radiochromatogram scanner. A nearly perfect correlation was found between these results so obtained and those given by liquid-scintillation counting of each metabolite after its elution from the paper.Part of this work was supported by grant n° 695 of the National Fonds voor Wetenschappelijk Geneeskundig Onderzoek.Stagiair of the Nationaal Fonds voor Wetenschappelijk Onderzoek.     

Primäre vollständige Degeneration des Spindelsystems bei „angeborener Gliederstarre“ Ein Beitrag zur Pathohistologie der Muskelspindeln

Zusammenfassung Bei systematischen Untersuchungen des Spindelsystems in einem Fall von angeborener Gliederstarre wurde in Ergänzung zu den bereits mitgeteilten Befunden am Bewegungsapparat (TIETZ und v. Brzezinski 1962) eine fortschreitende Degeneration der Muskelspindeln, beginnend mit eben feststellbaren Veränderungen an den intrafusalen Muskelfasern bzw. an den äquatorialen Kernhaufen im Bereich der sensiblen Nervenendigungen, bis zur völligen Desintegration der Spindeln festgestellt. Die Spindeldegeneration läuft der Degeneration der Arbeitsmuskulatur voraus und ist als primäre Veränderung anzusehen. Deshalb wird die angeborene Gliederstarre als primär neuropathisches Leiden angesehen. Die Spindeldegeneration und damit ihr Funktionsausfall soll zu einer funktionellen Lähmung der Arbeitsmuskulatur und sekundär zu deren Degeneration führen.

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Primary complete degeneration of the spindle system in congenital limb rigidity. A contribution to the pathohistology of the muscle spindle

Summary In systematic investigations of the spindle system in a case of congenital limb rigidity, a progressive degeneration of the muscle spindle was detected, ranging from barely perceptible changes in the intrafusal muscle fibers, or in the equatorial nuclear bags, to complete disintegration of the spindle. This serves as a supplement to the results on the muscle system already reported (Tietz and v.Brzezinski 1962). The spindle degeneration preceded the degeneration of the work-musculature and was regarded as the primary change. Therefore, thecongenital limb rigidity (angeborene Gliederstarre) was looked upon as a primary neuropathic disease. The spindle degeneration and the associated loss of function should lead to a functional paralysis of the work musculature, and secondarily to its degeneration.

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Herrn Prof. Dr.Hanns Schwarz, Direktor der Universitäts-Nervenklinik Greifswald, zum 65. Geburtstag gewidmet.     

Activation of atrial muscarinic K+ channels by low concentrations ofβγ subunits of rat brain G protein

Effects of G protein subunits from rat brain on cardiac K⁺ channel was examined in single atrial cells of guinea-pig, using patch clamp techniques. We found that 10 pM concentration of rat brain subunits preparation could activate the atrial muscarine receptor-gated K⁺ channel (I_K.ACh). Neither the detergent, CHAPS, used to suspend nor the boiled preparation activated I_K.ACh. Furthermore, preincubation of subunits preparation in Mg²⁺-free solution, which easily inactivated -GTP-S, did not affect -activation of I_K.ACh. We concluded, therefore, that subunits themselves can activate I_K.ACh.Supported by the grants from the Ministry of Education, Culture and Science of Japan and from the Calcium Signal Workshop on Cardiovascular Systems     

Lichtmikroskopische Untersuchungen über die Entwicklung vonTheileria annulata (Dschunkowsky und Luhs, 1904) inHyalomma anatolicum excavatum (Koch, 1844)

Summary Fully differentiated kinetes, average length 17.6m, appeared in the haemolymph of engorged nymphs usually 17 to 20 days after repletion. Kinetes were observed at first in the salivary glands on day 18 after repletion. The kinetes then transformed into fission bodies of about 10m in diameter, mainly in type III alveoli and less frequently in type II alveoli. The fission bodies grew up to a size of about 20m after several divisions of their nucleus. At this time the ticks moulted and no further development occurred until activation. Shortly before infestation the salivary glands began to proliferate, and rapid growth of the fission bodies was observed, especially in young ticks where development of infective particles (sporozoites) was concluded within two days. Development in feeding adult ticks apparently occurred in four major steps: (1) Division of primary fission bodies (sporonts) into numerous secondary fission bodies (primary sporoblasts), (2) division of secondary fission bodies into tertiary fission bodies (secondary sporoblasts), (3) production of particles (sporozoites) by tertiary fission bodies and release of particles into the saliva, and (4) degeneration of fission bodies and their host cell but further release of particles.The host cell was stimulated to giant growth, thus its diameter increased, on average, from 15 to 110 m. Heavy infections resulting from parasitaemias of >40% caused disease and mortality in the tick population. Development was much retarded by aging. In ticks starved for six months sporozoites did not develop before day five to seven of infestation. Sporozoites may not develop at all in six to nine month old female ticks during the infestation period. The significance of the described developmental stages ofT. annulata was discussed and a sexual generation postulated. The hypothetic development ofT. annulata in its tick vector was illustrated.

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Gefördert von der Deutschen Forschungsgemeinschaft (DFG)     

Improved transformation efficiency of Aspergillus niger using the homologous niaD gene for nitrate reductase

Summary Aspergillus niger transformation frequencies of up to 1,176 transformants per g DNA were achieved using the plasmid vector pSTA10 containing the A. niger nitrate reductase structural gene. Analysis of genomic endonuclease cleaved DNA from nitrate utilising transformants by DNA hybridisation, showed that most integration events are as a result of homologous recombination. The niaD transformation system was used successfully for the introduction of the unselected Escherichia coli fusion genes lacZ, encoding -galactosidase, and uidA, for -glucuronidase, as well as the Neurospora crassa tub-2 gene, for -tubulin. pSTA10 was also capable of transforming niaD mutants of other filamentous fungi such as A. nidulans, A. oryzae and Penicillium chrysogenum.     

Analysis of Cyclic Adenosine-3',5'-Monophosphate Levels in Structures of the “Informational” and “Motivational” Systems of the Rat Brain during Acquisition of a Conditioned Active Avoidance Reaction

Cyclic adenosine-3',5'-monophosphate (cAMP) levels in structures of the informational and motivational systems of the brain were measured during acquisition of a conditioned two-sided active avoidance reflex in rats. cAMP levels were measured in three groups of animals – intact animals, trained animals, and an active control group (given uncombined presentations of the conditioned (light) and unconditioned (electric shock) stimuli) – immediately after reproduction of the acquired reflex. Significant accumulation of cAMP levels in brain structures was seen in animals of the active control group in the hypothalamus and in trained animals in the left and right hippocampus and the right frontal cortex. Positive correlations were found between cAMP levels in symmetrical parts of the frontal cortex, amygdala, and hypothalamus in animals of all study groups. In addition, active control rats and trained rats showed interhemisphere and intrahemisphere correlations between cAMP levels in brain macrostructures, whose patterns were specific for each group. The pattern of correlations observed here is assessed from the point of view of the role of the informational and motivational structures in the organization of adaptive behavior.     

Neuron Activity in the Prefrontal Cortex of the Brain in Rats with Different Typological Characteristics in Conditions of Emotional Stimulation

Male Wistar rats were separated according to the emotional resonance method (groups of animals avoiding (altruists) and not avoiding (egotists) the pain cries of partner rats) and neuron activity in the prefrontal areas of the cortex was studied in the right and left hemispheres. Assessments were made of changes in the frequency of nerve cell spike activity (in relation to the baseline activity of neurons in sated animals) in rats subjected to one day of food deprivation and after electrical stimulation of emotionally positive (lateral hypothalamus) and negative (tegmentum of the midbrain) brain structures and after exposure to the pain cries of partner rats. The results of these experiments revealed a series of differences in the cell activities of the two groups of rats. In conditions of hunger, the discharge frequency in the altruists was higher than that in egotists. Cortical neuron responses to positive stimulation were greater than those to negative stimulation in rats of both groups. Intracerebral stimulation produced significantly greater increases in discharge frequency in neurons of both prefrontal areas of the cortex in altruists than in egotists. In both groups of rats, neurons in the right hemisphere responded to emotionally negative stimulation with significantly greater activation than cells in the left hemisphere, while activity in the left hemisphere was greater in conditions of emotionally positive stimulation. Altruists showed significantly greater neuron responses during exposure to pain cries from victim rats in both the right and left hemispheres. The responses of egotists to victim cries were not significantly different from baseline activity levels.     

Pyramidal tract of the cat: axon size and morphology

Summary The purpose of this work was to determine the number and morphology of pyramidal tract (PT) axons in the cat, using electron microscopy, modern methods of fixation, and computer-assisted morphometric analysis. Sections taken at the level of the medullary pyramids in three animals were fixed and magnified up to 10,000 x to produce photomicrographs. Morphological data were entered into computer files for analysis by tracing axon perimeters on micrographs mounted on a digitizer tablet. The number of axons per PT averaged 415,000, of which 88% were myelinated and 12% were unmyelinated. 90% of the myelinated axons fell in the diameter range 0.5–4.5 m. Axons larger than 9 m diameter accounted for 1% of the total; the largest were 20–23 m. Myelinated axon mean diameter was 1.98 m; because of the skewed distribution, with many small axons and a few very large axons, median diameter was 1.60 m. Size distribution was relatively uniform throughout the PT cross section, with all sizes represented in all regions. However, the more medial regions had a higher proportion of small fibers than the more lateral regions: mean medial diameter was 1.85 m while mean lateral diameter was 2.09 m. Myelin sheath thickness averaged 7.9% of fiber diameter for axons up to 11 m, but was constant at 0.9 m for larger fibers. Myelinated fibers were distorted from the circular shape in cross section, with a mean circularity index (or form factor) of 0.85, which implies that the fibers could swell about 15% without rupture of the cell membrane. Unmyelinated fibers averaged 0.18 m diameter (range 0.05–0.6 m); the largest unmyelinated axons were larger than the smallest myelinated axons. It is concluded that previous work greatly underestimated the number of axons in the cat pyramidal tract.