Ventilation and metabolism among rat strains

Strohl, Kingman P., Agnes J. Thomas, Pamela St. Jean, EvelynH. Schlenker, Richard J. Koletsky, and Nicholas J. Schork. Ventilation and metabolism among rat strains. J. Appl. Physiol. 82(1): 317-323, 1997.We examinedventilation and metabolism in four rat strains with variation in traitsfor body weight and/or blood pressure regulation.Sprague-Dawley [SD; 8 males (M), 8 females (F)], BrownNorway (BN; 10 M, 11 F), and Zucker (Z; 11 M, 12 F) rats were comparedwith Koletsky (K; 11 M, 11 F) rats. With the use of noninvasiveplethysmography, frequency, tidal volume, minute ventilation(E),O₂ consumption, andCO₂ production were derived atrest during normoxia (room air) and during the 5th minute of exposureto each of the following: hyperoxia (100% O₂), hypoxia (10%O₂-balanceN₂), and hypercapnia (7%CO₂-balance O₂). Statistical methods probedfor strain and sex effects, with covariant analysis by body weight,length, and body mass. During resting breathing, strain effects werefound with respect to both frequency (BN, Z > K, SD) and tidal volume(SD > BN, Z) but not to E. Sexinfluenced frequency (F > M) alone. Z rats had higher values forO₂ consumption,CO₂ production, and respiratoryquotient than the other three strains, with no independent effect bysex. During hyperoxia, frequency was greater in BN and Z than in SD orK rats; SD rats had a larger tidal volume than BN or Z rats; Z rats hada greater E than K rats; and M had alarger tidal volume than F. Strain differences persisted duringhypercapnia, with Z rats exhibiting the highest frequency andE values. During hypoxic exposure,strain effects were found to influenceE (SD > K, Z), frequency (BN > K), and tidal volume (SD > BN, K, Z). Body mass was only amodest predictor of E during normoxia, of both E and tidal volume withhypoxia, hypercapnia, or hyperoxia, and of frequency duringhypercapnia. We conclude that strain of rats, more than their body massor sex, has major and different influences on metabolism, the patternand level of ventilation during air breathing, and ventilation duringacute exposure to hypercapnia or hypoxia.

     

Phosphatidylcholine could be the source of 1,2-DAG which activates protein kinase C in EGF-stimulated colon carcinoma cells (HT29)

In our previous study (A. Balogh et al, Cell. Signalling 5 (6), 795-802, 1993.), we have shown that epidermal growth factor (EGF) increased protein kinase C (PKC) activities in colon carcinoma cell line (HT29), possibly through the increased 1,2-diacylglycerol (1,2-DAG) production via phosphatidylcholine (PC). Here we investigate the effect of the well-known PKC activator 12-O-tetradecanoyl-2 phorbol-13-acetate (TPA), on the levels of ³²P incorporation into EGF induced phosphatidylinositols (PI, PI4P, PI4, 5P₂) and different phospholipids (PC, PA, PS) as well as on induced tyrosine kinase activity. TPA significantly decreased the effects of EGF and it had the biggest inhibitory effect on EGF induced PC level. These data support our contention that PC plays an important role in the activation of PKC via 1,2-DAG production in the EGF stimulated pathway.     

Identification by in vitro complementation of regions required for cell-invasive activity of Bordetella pertussis adenylate cyclase toxin

The adenylate cyclase toxin (CyaA) of Bordetella pertussis is a 1706-residue protein composed of an amino-terminal adenylate cyclase (AC) domain linked to a 1300-residue channel-forming RTX ( r epeats in t o x in) haemolysin. The toxin delivers its AC domain into a variety of eukaryotic cells and impairs cellular functions by catalysing unregulated synthesis of cAMP from intracellular ATP. We have examined toxin activities of a set of deletion derivatives of CyaA. The results indicate that CyaA does not have a dedicated target cell-binding domain and that structural integrity and co-operation of all domains, as well as the post-translational fatty acylation mediated by an accessory protein CyaC, are all essential for target cell association and toxin activity of CyaA. When tested individually, all toxin derivatives were inactive and impaired in the tight association with the target cell surface. However, pairs of constructs with non-overlapping deletions complemented each other in vitro and exhibited a partially restored cytotoxic activity. This suggests that at least a part of the active toxin may act in the form of dimers or higher oligomers. The complementation analysis revealed that the last 217 residues of CyaA, containing the unprocessed secretion signal, form an autonomous domain essential for toxin activity, and that the region from residue 624 to 780 may be directly involved in delivery of the AC toxin into cells.     

Incorporation of the gene for a cell-cell channel protein into transformed cells leads to normalization of growth

Summary Incorporation of the gene for connexin 43, a cell-cell channel protein of gap junction, into the genome of communication-deficient transformed mouse 10T1/2 cells restored junctional communication and inhibited growth. Growth was slowed, saturation density reduced and focus formation suppressed, and these effects were contingent on overexpression of the exogenous gene and the consequent enhancement of communication. In coculture with normal cells the growth of the connexin overexpressors was completely arrested, as these cells established strong communication with the normal ones. Thus, in culture by themselves or in coculture, the connexin overexpressor cells grew like normal cells. These results demonstrate that the cell-cell channel is instrumental in growth control; they are the expected behavior if the channel transmits cytoplasmic growth-regulatory signals.     

Characterization ofκ-casein and keratin domains in fibrinogen

Summary Following the observation of a close sequence homology between the N-terminal moiety of the -chain of fibrinogen with large parts of-casein, the occurrence of a keratin domain in the middle section of the Achain is suggested.     

Correction to: Integrative transcriptomics reveals genotypic impact on sugar beet storability

Plant Molecular Biology - In the above mentioned publication, part of Fig. 6B was distorted (extra diagonal lines appeared). The original article has been corrected and the proper version...     

Design of a New Peptide Substrate Probe of the Putative Biomarker Legumain with Potential Application in Prostate Cancer Diagnosis Ex Vivo

International Journal of Peptide Research and Therapeutics - The lysosomal endoprotease legumain (asparaginyl endoprotease) has been proposed as a putative biomarker in prostate tumours, in which...