AN OCEAN-BASIN-WIDE MARK-RECAPTURE STUDY OF THE NORTH ATLANTIC HUMPBACK WHALE (MEGAPTERA NOVAEANGLIAE)

Although much is known about the humpback whale, Megaptera novaeangliae, regional studies have been unable to answer several questions that are central to the conservation and management of this endangered species. To resolve uncertainties about population size, as well as the spatial and genetic structure of the humpback whale population in the North Atlantic, we conducted a two-year ocean-basin-wide photographic and biopsy study in 1992-1993. Photographic and skin-biopsy sampling was conducted of animals in feeding and breeding areas throughout most of the range of this species in the North Atlantic, from the West Indies breeding grounds through all known feeding areas as far north as arctic Norway. A standardized sampling protocol was designed to maximize sample sizes while attempting to ensure equal probability of sampling, so that estimates of abundance would be as accurate and as precise as possible. During 666 d at sea aboard 28 vessels, 4,207 tail fluke photographs and 2,326 skin biopsies were collected. Molecular analyses of all biopsies included determination of sex, genotype using six microsatellite loci, and mitochondrial control region sequence. The photographs and microsatellite loci were used to identify 2,998 and 2,015 individual whales, respectively. Previously published results from this study have addressed spatial distribution, migration, and genetic relationships. Here, we present new estimates of total abundance in this ocean using photographic data, as well as overall and sex-specific estimates using biopsy data. We identify several potential sampling biases using only breeding-area samples and report a consistent mark-recapture estimate of oceanwide abundance derived from photographic identification, using both breeding and feeding-area data, of 10,600 (95% confidence interval 9,300-12,100). We also report a comparable, but less precise, biopsy-based estimate of 10,400 (95% confidence interval of 8,000-13,600). These estimates are significantly larger and more precise than estimates made for the 1980s, potentially reflecting population growth. In contrast, significantly lower and less consistent estimates were obtained using between-feeding-area or between-breeding-area sampling. Reasons for the lower estimates using the results of sampling in the same areas in subsequent years are discussed. Overall, the results of this ocean-basin-wide study demonstrate that an oceanwide approach to population assessment of baleen whales is practicable and results in a more comprehensive understanding of population abundance and biology than can be gained from smaller-scale efforts.     

Genetic Loci Associated with Alzheimer’s Disease and Cerebrospinal Fluid Biomarkers in a Finnish Case-Control Cohort

Objectives

To understand the relation between risk genes for Alzheimer’s disease (AD) and their influence on biomarkers for AD, we examined the association of AD in the Finnish cohort with single nucleotide polymorphisms (SNPs) from top AlzGene loci, genome-wide association studies (GWAS), and candidate gene studies; and tested the correlation between these SNPs and AD markers Aβ_1–42, total tau (t-tau), and phosphorylated tau (p-tau) in cerebrospinal fluid (CSF).

Methods

We tested 25 SNPs for genetic association with clinical AD in our cohort comprised of 890 AD patients and 701-age matched healthy controls using logistic regression. For the correlational study with biomarkers, we tested 36 SNPs in a subset of 222 AD patients with available CSF using mixed models. Statistical analyses were adjusted for age, gender and APOE status. False discovery rate for multiple testing was applied. All participants were from academic hospital and research institutions in Finland.

Results

APOE-ε4, CLU rs11136000, and MS4A4A rs2304933 correlated with significantly decreased Aβ_1–42 (corrected p<0.05). At an uncorrected p<0.05, PPP3R1 rs1868402 and MAPT rs2435211 were related with increased t-tau; while SORL1 rs73595277 and MAPT rs16940758, with increased p-tau. Only TOMM40 rs2075650 showed association with clinical AD after adjusting for APOE-ε4 (p = 0.007), but not after multiple test correction (p>0.05).

Conclusions

We provide evidence that APOE-ε4, CLU and MS4A4A, which have been identified in GWAS to be associated with AD, also significantly reduced CSF Aβ_1–42 in AD. None of the other AlzGene and GWAS loci showed significant effects on CSF tau. The effects of other SNPs on CSF biomarkers and clinical AD diagnosis did not reach statistical significance. Our findings suggest that APOE-ε4, CLU and MS4A4A influence both AD risk and CSF Aβ_1–42.     

Intracolonial genetic diversity increases chemical signaling by waggle-dancing honey bees, Apis mellifera

Extreme polyandry is a derived mating strategy that is uncommon in the Hymenoptera, but occurs in ecologically dominant taxa such as honey bees, leaf-cutter ants, and army ants. Honey bee queens that mate with many males confer a selective advantage to their colonies in part by generating genetically diverse foraging workforces that are more active than those of colonies with singly mated queens. These foragers produce more waggle-dance signals, each circuit of which attracts larger audiences of dance followers. We investigated the role that dancer-produced volatiles (“waggle-dance compounds”) play in facilitating signal exchange when mating frequency, and thus patriline number, differs. We found a 6- to 200-fold increase in quantities of three of four waggle-dance compounds in the airspace of multiple-patriline versus single-patriline colonies. Possible worker-level mechanisms underlying this difference were investigated by sampling compounds from dancers over similar intervals at the start of dances. The best-supported explanation was the presence of greater quantities of compounds on the abdomens of foragers as dance length increased rather than differences in quantities sampled between colony types or among patrilines. Workers who danced more frequently attracted more followers to the initial circuits of their first dance, but following response was not linked to quantities of compounds on dancers. While honey bee colonies with multiple patrilines have greater quantities of dancer-produced volatiles in them, high concentrations of these chemicals probably do not attract more dance followers to specific dancers. Thus, the role that these compounds may play in enhancing colony productivity requires clarification.     

Dynamin-Catalyzed Membrane Fission Requires Coordinated GTP Hydrolysis

Dynamin is the most-studied membrane fission machinery and has served as a paradigm for studies of other fission GTPases; however, several critical questions regarding its function remain unresolved. In particular, because most dynamin GTPase domain mutants studied to date equally impair both basal and assembly-stimulated GTPase activities, it has been difficult to distinguish their respective roles in clathrin-mediated endocytosis (CME) or in dynamin catalyzed membrane fission. Here we compared a new dynamin mutant, Q40E, which is selectively impaired in assembly-stimulated GTPase activity with S45N, a GTP-binding mutant equally defective in both basal and assembly-stimulated GTPase activities. Both mutants potently inhibit CME and effectively recruit other endocytic accessory proteins to stalled coated pits. However, the Q40E mutant blocks at a later step than S45N, providing additional evidence that GTP binding and/or basal GTPase activities of dynamin are required throughout clathrin coated pit maturation. Importantly, using in vitro assays for assembly-stimulated GTPase activity and membrane fission, we find that the latter is much more potently inhibited by both dominant-negative mutants than the former. These studies establish that efficient fission from supported bilayers with excess membrane reservoir (SUPER) templates requires coordinated GTP hydrolysis across two rungs of an assembled dynamin collar.     

Backbone NMR assignment of the internal interaction site of ALP

Earlier reports have shown that ALP has an internal interaction site. We were able to stablize the structure of this unfolded part to a great extent by aspartic acid, which allowed the backbone assignment. No secondary structure of the polypeptide was observed.     

Human epidermal growth factor: renal production and absence from plasma

Among the unsettled questions in the physiology of human epidermal growth factor (EGF) are (1) does EGF circulate in the blood and (2) what is the source of the abundant urinary immunoreactive EGF (irEGF). Therefore, we monitored the concentration of irEGF by an ultrasensitive assay in blood plasma from 5 healthy subjects every 20 min overnight carefully avoiding activation of platelets. Detectable levels (0.8-3.7 pM) were observed in only one of the subjects, in 5 of 29 samples. In random day-time plasma samples from 18 healthy adults, EGF was undetectable (less than 0.8 pM) in 13 subjects, and in 5 subjects EGF levels ranged from 2.2 to 4.9 pM. Furthermore, in 5 patients with a tumor in a functioning kidney we measured urinary relative irEGF concentration (nmol/mmol creatinine) before and after unilateral nephrectomy. The concentration fell by approximately 50%. Our findings are consistent with (1) blood irEGF residing exclusively in platelets, and (2) urinary irEGF originating from the kidneys.     

DNA content as a prognostic marker of oral lichen planus with a risk of cancer development

OBJECTIVE: To assess the presence of aneuploidy in oral lichen planus (OLP) and its usefulness as a prognostic marker. STUDY DESIGN: Eighty-one formalin-fixed, paraffin-embedded biopsy samples taken from atrophic-erosive OLP from 70 patients were studied. Approximately 150 random nuclei in basal and/or parabasal epithelia were analyzed with static cytometry. RESULTS: Aneuploidy was detected in 41% of samples. OLPs with ulcerations or location in the tongue had significantly higher values, respectively, for the 2.5c exceeding rate (ER) (p<0.001 and 0.001) and proliferation index (PI) (p = 0.012 and 0.013) than did lesions without ulcerations or at other locations. 2.5c ER was significantly higher in dysplastic OLP lesions (p < 0.001), and the significant value (p = 0.001)for 2.5c ER discriminating DNA aneuploidy was 15.3%. In multivariate analysis only the G2/M ER (G2/MER) was a significant independent predictor of developing cancer in OLP (OR 2.349, 95% CI 1.39-3.97, p = 0.001). CONCLUSION: Ulcerated atrophic-erosive OLPs of the tongue and with dysplasia are at increased risk of cancer development. 2.5c ER, PI and G2/MER might be useful in prognosticating the increased risk of malignancy in OLP.     

Surface porous fibre-reinforced composite bulk bone substitute

The aim of this study was to describe and evaluate the significance of a porous surface with bioactive glass granules (S53P4) covering an artificial bulk material based on polymethylmetacrylate (PMMA) and fibre-reinforced composite (FRC) technology. Effort was focused particularly on characters of the porous surface and biomechanical properties of the material in vitro, and test in vivo the implant in reconstruction in an experimental long bone segment defect model. The defect, 10 mm in length, created in the shaft of rabbit tibia, was reconstructed by the implant and fixed by intramedullary K-wires. The implant was incorporated within 4 weeks by new bone growth from the host bone covering particularly its posterior surface and cortex/implant junctions with bridging trabecular bone. Later, at 8 weeks, new bone was found also at the cortex/implant interface and in the medullary canal of the implant. Histometric measurements revealed direct bone/implant surface contact in 34% at the interface. Bioactive glass granules in the porous surface evoked the most direct contact with bone. The implants manufactured from PMMA only served as a control group, and showed significantly lower osteoconductive properties. Biomechanical measurements in vitro of fibre-reinforced PMMA specimens revealed values for bending strength and the flexural modulus to match them to human bone. This artificial bulk bone material based on PMMA/FRC technology seems to have proposing properties to be used as a bone substitute on load-bearing conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Honey Bee Workers That Are Pollen Stressed as Larvae Become Poor Foragers and Waggle Dancers as Adults

The negative effects on adult behavior of juvenile undernourishment are well documented in vertebrates, but relatively poorly understood in invertebrates. We examined the effects of larval nutritional stress on the foraging and recruitment behavior of an economically important model invertebrate, the honey bee (Apis mellifera). Pollen, which supplies essential nutrients to developing workers, can become limited in colonies because of seasonal dearths, loss of foraging habitat, or intensive management. However, the functional consequences of being reared by pollen-stressed nestmates remain unclear, despite growing concern that poor nutrition interacts with other stressors to exacerbate colony decline. We manipulated nurse bees’ access to pollen and then assessed differences in weight, longevity, foraging activity, and waggle-dance behavior of the workers that they reared (who were co-fostered as adults). Pollen stress during larval development had far-reaching physical and behavioral effects on adult workers. Workers reared in pollen-stressed colonies were lighter and shorter lived than nestmates reared with adequate access to pollen. Proportionally fewer stressed workers were observed foraging and those who did forage started foraging sooner, foraged for fewer days, and were more likely to die after only a single day of foraging. Pollen-stressed workers were also less likely to waggle dance than their unstressed counterparts and, if they danced, the information they conveyed about the location of food was less precise. These performance deficits may escalate if long-term pollen limitation prevents stressed foragers from providing sufficiently for developing workers. Furthermore, the effects of brief pollen shortages reported here mirror the effects of other environmental stressors that limit worker access to nutrients, suggesting the likelihood of their synergistic interaction. Honey bees often experience the level of stress that we created, thus our findings underscore the importance of adequate nutrition for supporting worker performance and their potential contribution to colony productivity and quality pollination services.     

Thermal biology of flight in a butterfly: genotype,flight metabolism,and environmental conditions

Knowledge of the effects of thermal conditions on animal movement and dispersal is necessary for a mechanistic understanding of the consequences of climate change and habitat fragmentation. In particular, the flight of ectothermic insects such as small butterflies is greatly influenced by ambient temperature. Here, variation in body temperature during flight is investigated in an ecological model species, the Glanville fritillary butterfly (Melitaea cinxia). Attention is paid on the effects of flight metabolism, genotypes at candidate loci, and environmental conditions. Measurements were made under a natural range of conditions using infrared thermal imaging. Heating of flight muscles by flight metabolism has been presumed to be negligible in small butterflies. However, the results demonstrate that Glanville fritillary males with high flight metabolic rate maintain elevated body temperature better during flight than males with a low rate of flight metabolism. This effect is likely to have a significant influence on the dispersal performance and fitness of butterflies and demonstrates the possible importance of intraspecific physiological variation on dispersal in other similar ectothermic insects. The results also suggest that individuals having an advantage in low ambient temperatures can be susceptible to overheating at high temperatures. Further, tolerance of high temperatures may be important for flight performance, as indicated by an association of heat‐shock protein (Hsp70) genotype with flight metabolic rate and body temperature at takeoff. The dynamics of body temperature at flight and factors affecting it also differed significantly between female and male butterflies, indicating that thermal dynamics are governed by different mechanisms in the two sexes. This study contributes to knowledge about factors affecting intraspecific variation in dispersal‐related thermal performance in butterflies and other insects. Such information is needed for predictive models of the evolution of dispersal in the face of habitat fragmentation and climate change.