Some characteristics of urea accumulation in the renal cortex tissue of rats and dogs

The urea concentration in the renal cortex ([RC]), liver ([L]) and skeletal muscle ([SM]) of non-diuretic Wistar rats was measured chemically and after an i.m. injection of 14C-urea and was compared with the plasma urea concentration ([P]). [L]/[P] and [SM]/[P] always equalled 1, irrespective of whether they were measured chemically or by means of radioactivity. [RC]/[P] was 2.81, again without any difference between chemical and radioactive measurement. The ratio of the chemically measured urea concentration in the renal cortex and plasma of mongrel dogs was 5.71, i.e. significantly higher than in rats (p less than 0.01). The intrarenal infusion of KCN, iodoacetate and ouabain did not alter it significantly (5.52, p greater than 0.05). Active transport, in whatever form, does not seem to be the cause of the high urea concentration in rat and dog renal cortex.     

Effect of Mercurascan on sodium transport in frog skin and bladder

The authors studied the effect of Mercurascan (MSC) (a hydroxy- mercury derivative of fluorescein) on electrical parameters, namely potential difference (P.D.) and short circuit current (S.C.C.) of frog skin and on the ability of frog bladder tissue to accumulate sodium ions in experiments in vitro. It was found that MSC, in 10(-4) mol/l concentration, reduced the S.C.C., after a brief initial increase, to 5% of the original value and that the P.D. fell steadily right from the outset. In 10(-5) mol/l concentration it raised the S.C.C. by 60% and the increase lasted several hours. The P.D. was unaffected. In 10(-7) and 10(-6) mol/l concentration MSC had no effect on the NA+ content of a nonpolarized frog bladder tissue preparation, but a 10(-5) nol/l concentration sharply reduced it. The effect of MSC on membrane Na+--K+ ATPase, i.e. on the energy metabolism of cellular tissue, is discussed with reference to these results.     

Immunocytochemical detection of the growth-associated protein B-50 by newly characterized monoclonal antibodies in human brain and muscle

The growth-associated protein B-50 also termed GAP-43, F1, pp46, P-57 and neuromodulin is a nervous tissuespecific protein kinase C (PKC) substrate that is considered to play a major role in neurite formation, regeneration, and neuroplasticity. We describe the isolation of seven mouse monoclonal antibodies (Mabs) directed against B-50. The Mabs are produced against the bovine B-50, selected by ELISA for cross-reactivity with its human counterpart, and evaluated on Western blots in comparison with the well-characterized affinity-purified rabbit polyclonal antibodies to rat-B-50. The Western blots show that the Mabs NM1, NM4, and NM6 recognize specifically the B-50 of bovine, human, and rat brain extract and the purified PKC phosphorylated and unphosphorylated rat B-50 isoforms. The Mabs NM2 and NM3 cross-react with bovine B-50 immunoreactive c-kinase substrate (BICKS), a protein sharing a 17 amino acid sequence homology with B-50. Two Mabs are useful for the detection of B-50 immunoreactivity in formalin-fixed human and rat brain tissues. In human specimen of the hippocampus, a characteristic neuropil distribution of B-50 is detected by the Mabs. In human muscle, Mabs reveal B-50 in nerve bundles and in axons at motor end plates. Thus, these Mabs are useful in investigating the function and localization of the B-50 protein.     

Detection of genetic variants affecting cattle behaviour and their impact on milk production: a genome‐wide association study

Behaviour traits of cattle have been reported to affect important production traits, such as meat quality and milk performance as well as reproduction and health. Genetic predisposition is, together with environmental stimuli, undoubtedly involved in the development of behaviour phenotypes. Underlying molecular mechanisms affecting behaviour in general and behaviour and productions traits in particular still have to be studied in detail. Therefore, we performed a genome‐wide association study in an F₂ Charolais × German Holstein cross‐breed population to identify genetic variants that affect behaviour‐related traits assessed in an open‐field and novel‐object test and analysed their putative impact on milk performance. Of 37 201 tested single nucleotide polymorphism (SNPs), four showed a genome‐wide and 37 a chromosome‐wide significant association with behaviour traits assessed in both tests. Nine of the SNPs that were associated with behaviour traits likewise showed a nominal significant association with milk performance traits. On chromosomes 14 and 29, six SNPs were identified to be associated with exploratory behaviour and inactivity during the novel‐object test as well as with milk yield traits. Least squares means for behaviour and milk performance traits for these SNPs revealed that genotypes associated with higher inactivity and less exploratory behaviour promote higher milk yields. Whether these results are due to molecular mechanisms simultaneously affecting behaviour and milk performance or due to a behaviour predisposition, which causes indirect effects on milk performance by influencing individual reactivity, needs further investigation.