Coastal swimming patterns of white sharks (<Emphasis Type="Italic">Carcharodon carcharias</Emphasis>) at Mossel Bay,South Africa

Between June and December 2005, active and passive acoustic telemetry was used to examine fine scale movements of 13 white sharks (Carcharodon carcharias) (ten passive, three active) at Mossel Bay. A total of 24 active trackings (ranging from 2 h to 103 h in duration) were conducted. Patterns of rate of movement (ROM), swimming linearity (LI), swimming bearing, and instantaneous swimming speed (ISS) were assessed. A conversion quotient (Q) of 1.21 between ISS and ROM (10 min sample interval) was calculated suggesting ROM is a good indicator of white shark activity. The mean ROM for tracked sharks was 0.52 m·s⁻¹, with a greatest sustained ROM of 1.33 m·s⁻¹ (4.8 km·h⁻¹). Sharks displayed greatest LI and ROM during directional travels between the three persistent aggregation sites. The majority of the shark movement was, however, non-linear as the sharks repeat patrolled at the three aggregation sites. Two of these sites were not associated with pinniped presence, and sharks typically patrolled back and forth parallel to the shore line at a comparatively low ROM which suggested resting. The third aggregation site was adjacent to Seal Island, and despite low LI, sharks displayed a high ROM, indicating high activity levels. We propose that the high ROM is related to maximising search area when patrolling to hunt Cape fur seals (Arctocephalus p. pusillus).     

Isoforms of soybean seed oil body membrane protein 24 kDa oleosin are encoded by closely related cDNAs

We have characterized two cDNA clones for 24 kDa soybean oleosin, the seed oil body membrane protein. Differences in the predicted amino acid sequences of the two clones and the presence of a doublet on immunoblots indicate that 24 kDa oleosin exists in at least two isoforms in soybean. The predicted amino acid sequence also contains a unique carboxy terminal region that is dominated by a series of different tandem amino acid repeats.     

CCN3/CCN2 regulation and the fibrosis of diabetic renal disease

Prior work in the CCN field, including our own, suggested to us that there might be co-regulatory activity and function as part of the actions of this family of cysteine rich cytokines. CCN2 is now regarded as a major pro-fibrotic molecule acting both down-stream and independent of TGF-β1, and appears causal in the disease afflicting multiple organs. Since diabetic renal fibrosis is a common complication of diabetes, and a major cause of end stage renal disease (ESRD), we examined the possibility that CCN3 (NOV), might act as an endogenous negative regulator of CCN2 with the capacity to limit the overproduction of extracellular matrix (ECM), and thus prevent, or ameliorate fibrosis. We demonstrate, using an in vitro model of diabetic renal fibrosis, that both exogenous treatment with CCN3 and transfection with the over-expression of the CCN3 gene in mesangial cells markedly down-regulates CCN2 activity and blocks ECM over-accumulation stimulated by TGF-β1. Conversely, TGF-β1 treatment reduces endogenous CCN3 expression and increases CCN2 activity and matrix accumulation, indicating an important, novel yin/yang effect. Using the db/db mouse model of diabetic nephropathy, we confirm the expression of CCN3 in the kidney, with temporal localization that supports these in vitro findings. In summary, the results corroborate our hypothesis that one function of CCN3 is to regulate CCN2 activity and at the concentrations and conditions used down-regulates the effects of TGF-β1, acting to limit ECM turnover and fibrosis in vivo. The findings suggest opportunities for novel endogenous-based therapy either by the administration, or the upregulation of CCN3.     

Synthesis of N pi-methylhistamine and N alpha-methylhistamine by purified rabbit lung indolethylamine N-methyltransferase

N tau-Methylhistamine is a major inactive metabolite of histamine and is formed by histamine N-methyltransferase (EC 2.1.1.8). However, a controversy exists concerning the presence of other N-methylated histamines, such as N pi- and N alpha-methylhistamine in mammalian tissues. Indolethylamine N-methyltransferase is present in mammalian tissues with the rabbit lung containing the highest concentration, but the physiologic function of this enzyme remains unclear. Using rabbit lung as a tissue source, we purified indolethylamine N-methyltransferase 260-fold and separated it completely from histamine N-methyltransferase. Histamine was a substrate for purified indolethylamine N-methyltransferase and unlike histamine N-methyltransferase which exclusively formed N tau-methylhistamine, indolethylamine N-methyltransferase catalyzed the in vitro formation of both N pi-methylhistamine and N alpha-methylhistamine. In contrast to histamine N-methyltransferase, indolethylamine N-methyltransferase activity was not inhibited by either high histamine concentrations or by quinacrine. Thus, mammalian tissues contain an enzyme capable of forming N pi-methylhistamine and N alpha-methylhistamine. This supports the concept of the existence of these compounds and suggests they may serve a physiologic function in mammals.     

The involvement of cell wall expansion in the two modes of mycelium formation of Candida albicans

When budding cells of Candida albicans are starved for 20 min and then diluted into fresh nutrient medium at 37 degrees C, pH 6.7, they form mycelia by two alternative modes. For cells with small buds, the bud expands apically, resulting in a transiently tapered daughter cell. With continued growth, the daughter cell tapers into an elongated mycelium. For cells with large buds, the bud completes expansion in the budding form, the mother cell and then the daughter bud evaginate, and the evaginations grow as mycelia. The present study investigates whether the temporal and spatial changes in the zones of wall expansion during bud growth are involved in the two modes of mycelium formation. Data are presented which demonstrate that the transition circumference which determines the two modes of mycelium formation and the transition circumference at which the active apical expansion zone shuts down are both 7 micron. This exact correlation suggests that starved cells with buds with a circumference of less than 7 micron form mycelia in the tapering mode due to the reactivation of the still present apical expansion zone, and that starved cells with buds with a circumference greater than 7 micron complete bud growth by general expansion due to the absence of the apical expansion zone at the time of starvation.     

Awareness during electromyographic biofeedback: Of signal or process?

During relaxation training, awareness of trial-to-trial changes in frontalis-muscle tension levels was assessed with and without auditory electromyographic(EMG) biofeedback. Immediately after each 128-sec training trial, the subject was required to guess whether muscle tension indexed by EMG activity increased(“Up”) or decreased(“Down”) relative to the immediately preceding trial. The probability of correct guessing, P(c), improved as the absolute difference in EMG increased between trials only when biofeedback was presented. For subjects not receiving biofeedback, P(c) remained low even when the absolute difference between trials was large. Subjects in each condition employed a strategy to guess “Down” more often consistent with the expectation that they were being trained to relax. The “Down” set strategy was shown to be separable from the informational basis of P(c) provided by biofeedback. This procedure can be employed to evaluate central assumptions of biofeedback relating to posttraining awareness of changes in muscle tension and the relationship between awareness and control of muscle tension.