Development of myoglobin concentration and acid buffering capacity in harp (<Emphasis Type="Italic">Pagophilus groenlandicus</Emphasis>) and hooded (<Emphasis Type="Italic">Cystophora cristata</Emphasis>) seals from birth to maturity

Pinnipeds rely on muscle oxygen stores to help support aerobic diving, therefore muscle maturation may influence the behavioral ecology of young pinnipeds. To investigate the pattern of muscle development, myoglobin concentration ([Mb]) and acid buffering ability (β) was measured in ten muscles from 23 harp and 40 hooded seals of various ages. Adult [Mb] ranged from 28–97 to 35–104 mg g tissue⁻¹ in harp and hooded seals, respectively, with values increasing from the cervical, non-swimming muscles to the main swimming muscles of the lumbar region. Neonatal and weaned pup muscles exhibited lower (~30% adult values) and less variable [Mb] across the body than adults. In contrast, adult β showed little regional variation (60–90 slykes), while high pup values (~75% adult values) indicate significant in utero development. These findings suggest that intra-uterine conditions are sufficiently hypoxic to stimulate prenatal β development, but that [Mb] development requires additional postnatal signal such as exercise, and/or growth factors. However, because of limited development in both β and [Mb] during the nursing period, pups are weaned with muscles with lower aerobic and anaerobic capacities than those of adults.     

A network-based approach to identify substrate classes of bacterial glycosyltransferases

Background

Bacterial interactions with the environment- and/or host largely depend on the bacterial glycome. The specificities of a bacterial glycome are largely determined by glycosyltransferases (GTs), the enzymes involved in transferring sugar moieties from an activated donor to a specific substrate. Of these GTs their coding regions, but mainly also their substrate specificity are still largely unannotated as most sequence-based annotation flows suffer from the lack of characterized sequence motifs that can aid in the prediction of the substrate specificity.

Results

In this work, we developed an analysis flow that uses sequence-based strategies to predict novel GTs, but also exploits a network-based approach to infer the putative substrate classes of these predicted GTs. Our analysis flow was benchmarked with the well-documented GT-repertoire of Campylobacter jejuni NCTC 11168 and applied to the probiotic model Lactobacillus rhamnosus GG to expand our insights in the glycosylation potential of this bacterium. In L. rhamnosus GG we could predict 48 GTs of which eight were not previously reported. For at least 20 of these GTs a substrate relation was inferred.

Conclusions

We confirmed through experimental validation our prediction of WelI acting upstream of WelE in the biosynthesis of exopolysaccharides. We further hypothesize to have identified in L. rhamnosus GG the yet undiscovered genes involved in the biosynthesis of glucose-rich glycans and novel GTs involved in the glycosylation of proteins. Interestingly, we also predict GTs with well-known functions in peptidoglycan synthesis to also play a role in protein glycosylation.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-349) contains supplementary material, which is available to authorized users.     

Mitochondrial haplotype diversity in the tortoise species <Emphasis Type="Italic">Testudo graeca</Emphasis> from North Africa and the Middle East

Background  

To help conservation programs of the endangered spur-thighed tortoise and to gain better insight into its systematics, genetic variation and evolution in the tortoise species Testudo graeca (Testudines: Testudinidae) was investigated by sequence analysis of a 394-nucleotide fragment of the mitochondrial 12S rRNA gene for 158 tortoise specimens belonging to the subspecies Testudo graeca graeca, Testudo graeca ibera, Testudo graeca terrestris, and a newly recognized subspecies Testudo graeca whitei. A 411-nucleotide fragment of the mitochondrial D-loop was additionally sequenced for a subset of 22 T. graeca, chosen because of their 12S gene haplotype and/or geographical origin.     

Gene expression in cortex and hippocampus during acute pneumococcal meningitis

Background  

Pneumococcal meningitis is associated with high mortality (~30%) and morbidity. Up to 50% of survivors are affected by neurological sequelae due to a wide spectrum of brain injury mainly affecting the cortex and hippocampus. Despite this significant disease burden, the genetic program that regulates the host response leading to brain damage as a consequence of bacterial meningitis is largely unknown.     

Diving behaviour of hooded seals (Cystophora cristata) in the Greenland and Norwegian Seas

Satellite-linked dive recorders were used to collect data on depths and durations of ∼120,000 dives by 16 hooded seals (Cystophora cristata). Following tagging after moult (four males, eight females) and breeding (four females) off east Greenland, seals dispersed widely in the northeast Atlantic during 172 ± 97 days (mean satellite-linked dive recorder lifetime ± SD). Meso/bathypelagic dives of 5- to 25-min duration to 100–600 m dominated (75%), but some very deep (≥1016 m) and long (>52 min) dives occurred. Diving in open ocean was continuous, with an estimated 90.7±0.8% (mean±SE) of time spent submerged. The proportion of time spent submerged was similar during night and day, but dives during the day were generally deeper and longer (P < 0.05) than during the night. Also, dives in winter were deeper and longer than in summer. Published data on the distribution of likely prey suggest that Greenland halibut (Reinhardtius hippoglossoides), redfish (Sebastes spp.), polar cod (Boreogadus saida), herring (Clupea harengus), squid (Gonatus fabricii) and blue whiting (Micromesistius poutassou) are important prey of hooded seals. Accepted: 22 January 1999     

Seasonal variations in basal metabolic rate, lower critical temperature and responses to temporary starvation in the arctic fox (Alopex lagopus) from Svalbard

Metabolic rates of four resting, post-absorptive male adult summer- and winter-adapted captive arctic foxes (Alopex lagopus) were recorded. Basal metabolic rates (BMR) varied seasonally with a 36% increase from winter to summer, while body mass was reduced by 17% in the same period. The lower critical temperature (T _1c) of the winter-adapted arctic fox was estimated to −7°C, whereas T _lc during summer was 5°C. The similarity of these values, which are much higher than hitherto assumed (e.g. Scholander et al. 1950b), is mainly due to a significantly (P<0.05) lower BMR in winter than in summer. Body core (stomach) temperature was stable, even at ambient temperatures as low as −45°C, but showed a significant (P<0.05) seasonal variation, being lower in winter (39.3±0.33°C) than in summer (39.8±0.16°C). The thermal conductivity of arctic fox fur was the same during both seasons, whereas the thermal conductance in winter was lower than in summer. This was reflected in an increase in fur thickness of 140% from summer to winter, and in a reduced metabolic response to ambient temperatures below T _lc in winter. Another four arctic foxes were exposed to three periods of forced starvation, each lasting 8 days during winter, when body mass is in decline. No significant reduction in mass specific BMR was observed during the exposure to starvation, and respiratory quotient was unchanged at 0.73±0.02 during the first 5 days, but dropped significantly (P<0.05) to 0.69±0.03 at day 7. Locomotor activity and body core (intraperitoneal) temperature was unaltered throughout the starvation period, but body mass was reduced by 18.5±2.1% during these periods. Upon re-feeding, locomotor activity was significantly (P<0.05) reduced for about 6 days. Energy intake was almost doubled, but stabilised at normal levels after 11 days. Body mass increased, but not to the level before the starvation episodes. Instead, body mass increased until it reached the reduced body mass of ad libitum fed control animals. This indicates that body mass in the arctic fox is regulated according to a seasonally changing set point.     

Validation of a device for accurate timing of feeding events in marine animals

Two acceleration data loggers, each measuring surging and heaving acceleration, were attached to the head and mandible of three captive hooded seals, Cystophora cristata, for detection of underwater feeding events. Three sizes of prey: Atlantic herring (large), capelin (medium), and half a capelin (small) were tested. A highpass frequency-filtering method at 3 Hz provided more distinct prey ingestion signals for both head and mandible acceleration. The surge-axis signals from head acceleration suggested that the seals ingested their prey not only by biting, but also by thrusting. Moreover, prey ingestion movements showed higher surging acceleration from mandible than from head (mean ± SD from head: 5.37 ± 4.45 m s⁻², from mandible: 8.43 ± 5.15 m s⁻², n = 153), indicating that the data from the head is not required for precise identification of feeding events. Thus, our mandible acceleration device provides a practical method for the timing of underwater feeding events in seals.     

Panting in reindeer (Rangifer tarandus)

Two winter-insulated Norwegian reindeer (Rangifer tarandus tarandus) were exposed to air temperatures of 10, 20, 30, and 38 degrees C while standing at rest in a climatic chamber. The direction of airflow through nose and mouth, and the total and the nasal minute volumes, respectively, were determined during both closed- and open-mouth panting. The animals alternated between closed- and open-mouth panting, but the proportion of open-mouth panting increased with increasing heat load. The shifts from closed- to open-mouth panting were abrupt and always associated with a rise in respiratory frequency and respiratory minute volume. During open-mouth panting, the direction of airflow was bidirectional in both nose and mouth, but only 2.4 +/- (SD) 1.1% of the air was routed through the nose. Estimates suggest that the potential for selective brain cooling is markedly reduced during open-mouth panting in reindeer as a consequence of this airflow pattern.     

Volume capacity and contraction control of the seal spleen

Cabanac, Arnaud, Lars P. Folkow, and Arnoldus Schytte Blix.Volume capacity and contraction control of the seal spleen. J. Appl. Physiol. 82(6):1989-1994, 1997.Volume changes in the spleens of hooded seals(Cystophora cristata) and harp seals(Phoca groenlandica) were measuredplethysmographically in vitro in response to epinephrine,norepinephrine, isoprenaline, phentolamine, and acetylcholine. Dilated spleens contracted forcefullywithin 1-3 min of -adrenoceptor activation with 1.0-5.0µg epinephrine/kg body mass, whereas stimulation of -adrenoceptorsand cholinergic receptors had little effect. The mass of dilated hoodedseal spleens corresponded to 2-4%(n = 7) of body mass, with volume (V;ml) relating to body mass (M; kg) as follows: V = 12.0M + 910 (r² = 0.96, n = 4). Thus the spleen of a 250-kghooded seal maximally expels 3.9 liters, or 13%, of its estimatedtotal blood volume. Average hematocrit in splenic venous outflow fromdilated spleens was 90 ± 3% (n = 3) in hooded seals and 85% (n = 2) inharp seals. From these data we have estimated that the aerobic divinglimit of a 250-kg hooded seal increases only 105 s, at the most, if complete emptying of the spleen occurs during diving, while the corresponding estimate for a 112-kg harp seal is 80 s.