Dear All We are pleased to announce the recent publication of the following papers. The first article is open access, and a link is provided below to the journal web site where the article can be downloaded. A pdf copy of the second article will be provided upon request. We realize that the first paper is not directly related to marine mammals, but it may be of interest to those interested in the physiological ecology of these animals.
Fahlman, A. B.L. Bostrom, K.H. Dillon, D.R. Jones. 2011. The genetic component of the forced diving bradycardia response in mammals. Frontiers in Physiology. 2: 63 doi: 10.3389/fphys.2011.00063 We contrasted the forced diving bradycardia between two genetically similar (inbred) rat strains (Fischer and Buffalo), compared to that of outbred rats (Wistar). The animals were habituated to forced diving for 4 weeks. Each animal was then tested during one 40-sec dive on each of 3 days. The heart rate (fH) was measured before, during, and after each dive. Fischer and Buffalo exhibited marked difference in dive bradycardia (Fischer: 120.9 ± 14.0 beats • min-1 vs. Buffalo: 92.8 ± 12.8 beats • min-1, P < 0.05). Outbred rats showed an intermediate response (103.0 ± 30.9 beats • min-1) but their between-animal variability in mean dive fH and pre-diving resting fH were higher than the inbred strains (P < 0.05), which showed no difference (P > 0.05). The decreased variability in fH in inbred rats as compared with the outbred group indicates that reduced genetic variability minimizes variability of the diving bradycardia between individuals. Heritability within strains was assessed by the repeatability (R) index and was 0.93 ± 0.05 for the outbred, 0.84 ± 0.16 for Buffalo, and 0.80 ± 0.12 for Fischer rats for fH during diving. Our results suggest that a portion of the mammalian diving bradycardia may be a heritable trait. http://www.frontiersin.org/aquatic_physiology/10.3389/fphys.2011.00063/abstract Fahlman, A. S.H. Loring, M. Ferrigno, C. Moore, G. Early, M. Niemeyer, B. Lentell, F. Wenzel, R. Joy, M. 2011. Moore. Inflation and deflation pressure-volume loops in breath-hold diving marine mammals. In Press Journal to Experimental Biology. 214: 3822-3828. Excised lungs from eight marine mammal species [harp seal (Pagophilus groenlandicus), harbor seal (Phoca vitulina), gray seal (Halichoerus grypus), Atlantic white-sided dolphin (Lagenorhynchus acutus), common dolphin (Delphinus delphis), Rissoʼs dolphin (Grampus griseus), long-finned pilot whale (Globicephala melas) and harbor porpoise (Phocoena phocoena)] were used to determine the minimum air volume of the relaxed lung (MAV, N=15), the elastic properties (pressure–volume curves, N=24) of the respiratory system and the total lung capacity (TLC). Our data indicate that mass-specific TLC (sTLC, l kg–1) does not differ between species or groups (odontocete vs phocid) and agree with that estimated (TLCest) from body mass (Mb) by applying the equation: TLCest=0.135Mb0.92. Measured MAV was on average 7% of TLC, with a range from 0 to 16%. The pressure–volume curves were similar among species on inflation but diverged during deflation in phocids in comparison with odontocetes. These differences provide a structural basis for observed species differences in the depth at which lungs collapse and gas exchange ceases. If you have any questions, please do not hesitate to send me an e-mail. Sincerely, Andreas Department of Life Sciences Texas A&M University-Corpus Christi 6300 Ocean Drive, Unit 5892 Corpus Christi, TX 78412 Ph. +1-361-825-3489 Fax. +1-361-825-2025 e-mail: andreas.fahl...@tamucc.edu<mailto:andreas.fahl...@tamucc.edu>
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