The commercial harvest of ice-associated seals in the Sea of Okhotsk, 1972-1994.

Sealing log books from 75 out of 79 commercial harvest cruises carried out between 1972 and 1994 in the Sea of Okhotsk, Russia, were analyzed to describe spatial and temporal allocation of ice-associated seal harvest effort, species composition of catches, total harvest rates, and related parameters for species including ringed (Pusa hispida), ribbon (Histriophoca fasciata), bearded (Erignathus barbatus) and spotted (Phoca largha) seal. Variations in catch per unit effort were explored in relation to year, sea ice conditions, day of the year, and geographic location. In most years, the harvest was predominantly represented by ringed seals (mean = 0.43, range 0.25-0.67), followed by ribbon (mean = 0.31, range 0.15-0.43), spotted (mean = 0.19, range 0.11-0.35) and bearded seals (mean = 0.07, range 0.03-0.14). The struck-and-lost percentages were as high as 30-35% for ringed, bearded and spotted seals and 15-20% for ribbon seals. Catch per unit effort (number of seals/skiff*day) for ringed, ribbon, and spotted seals had a similar seasonal pattern with a distinct spike in catches for spotted seals in the first week of May, for ribbon seals in the last week of May, and for ringed seals in the second week of June. Catches of bearded seals showed a less pronounced temporal structure with a gradual increase toward the end of the harvest season in the majority of years. Spatial distribution of harvest effort followed closely with seal distribution obtained from aerial surveys. These data could be used as a source of information on seal herd location throughout the breeding and molting seasons and for more complex demographic or life-table models. We did not find any evidence of the decline of catch per unit effort over the study period. Timely introduction of state regulations and efficient harvest management apparently prevented severe depletion of ice-associated seal populations in the Sea of Okhotsk during the periods of their intense exploitation

GAM fit and 95% CI for mean observed catch per unit effort, 1972–1994.

<p>Note that the Y-axis scales vary with species.</p

Yersinia pestis Caf1 Protein: Effect of Sequence Polymorphism on Intrinsic Disorder Propensity, Serological Cross-Reactivity and Cross-Protectivity of Isoforms.

Yersinia pestis Caf1 is a multifunctional protein responsible for antiphagocytic activity and is a key protective antigen. It is generally conserved between globally distributed Y. pestis strains, but Y. pestis subsp. microtus biovar caucasica strains circulating within populations of common voles in Georgia and Armenia were reported to carry a single substitution of alanine to serine. We investigated polymorphism of the Caf1 sequences among other Y. pestis subsp. microtus strains, which have a limited virulence in guinea pigs and in humans. Sequencing of caf1 genes from 119 Y. pestis strains belonging to different biovars within subsp. microtus showed that the Caf1 proteins exist in three isoforms, the global type Caf1NT1 (Ala48 Phe117), type Caf1NT2 (Ser48 Phe117) found in Transcaucasian-highland and Pre-Araks natural plague foci #4-7, and a novel Caf1NT3 type (Ala48 Val117) endemic in Dagestan-highland natural plague focus #39. Both minor types are the progenies of the global isoform. In this report, Caf1 polymorphism was analyzed by comparing predicted intrinsic disorder propensities and potential protein-protein interactivities of the three Caf1 isoforms. The analysis revealed that these properties of Caf1 protein are minimally affected by its polymorphism. All protein isoforms could be equally detected by an immunochromatography test for plague at the lowest protein concentration tested (1.0 ng/mL), which is the detection limit. When compared to the classic Caf1NT1 isoform, the endemic Caf1NT2 or Caf1NT3 had lower immunoreactivity in ELISA and lower indices of self- and cross-protection. Despite a visible reduction in cross-protection between all Caf1 isoforms, our data suggest that polymorphism in the caf1 gene may not allow the carriers of Caf1NT2 or Caf1NT3 variants escaping from the Caf1NT1-mediated immunity to plague in the case of a low-dose flea-borne infection

Seal harvest locations in the Sea of Okhotsk in April-July, 1972–1994 combined.

<p>Sea ice extent [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0182725#pone.0182725.ref012" target="_blank">12</a>] is provided for illustrative purposes for the year of 1980 (high ice year).</p

Observed catch per unit effort for 1972–1994 combined (right Y-axis) plotted against ordinal day.

<p>The boxes show the number and range of 50% of observations in each group; bold horizontal lines in boxes indicate median number of seals caught, dots indicate outliers in the data. The left Y-axis is for the GAM smooths for each year and multi-year mean. Note that both Y-axis scales vary with species.</p

Vessel-based seal harvest totals based on sealing log books and official vessel and shore-based harvest rates according to Okhotskrybvod reports from 1972–1994 in the Sea of Okhotsk.

<p>Note that these data do not include seals harvested in the west coast of Kamchatka (under jurisdiction of Kamchatrybvod). Abundance estimates are based on available population aerial survey results.</p

Evaluating intrinsic disorder propensities of different Caf1 isoforms.

<p>(A) Disorder profiles obtained for the analyzed proteins by PONDR® VSL2 (Caf1_NT1 (dashed dark yellow line), Caf1_NT2 (solid gray line), and Caf1_NT3 (dotted dark red line)) and PONDR-FIT (Caf1_NT1 (dashed yellow line), Caf1_NT2 (solid black line), and Caf1_NT3 (dotted red line)). Disorder scores above 0.5 correspond to the residues/regions predicted to be intrinsically disordered. Colored shades around the corresponding PONDR-FIT curves represent distributions of errors in evaluation of disorder propensity. (B) Comparison of the disorder profiles obtained for Caf1 isoforms by PONDR VLXT (Caf1_NT1 (dashed dark yellow line), Caf1_NT2 (solid gray line), and Caf1_NT3 (dotted dark red line)) and their intrinsic disorder-based interactability (Caf1_NT1 (dashed yellow line), Caf1_NT2 (solid black line), and Caf1_NT3 (dotted red line)) predicted using the ANCHOR algorithm [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0162308#pone.0162308.ref051" target="_blank">51</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0162308#pone.0162308.ref052" target="_blank">52</a>]. To simplify comparison of disorder predisposition and presence of potential disorder-based binding sites, ANCHOR data are present in the (1 –ANCHOR score form). Therefore, in PONDR® VLXT profiles, regions with scores above 0.5 are predicted to be intrinsically disordered, whereas in the ANCHOR profiles, regions with probability below 0.5 are predicted as binding regions.</p

Caf1 isoform cross-reactivity.

<p>Mice were immunized with NT1 (blue bars), NT2 (red bars) or NT3 (green bars) and then bled on day 29 after first (I) or day 43 after second immunization (II) and sera samples were tested in ELISA against NT1, NT2 or NT3 isoforms. Data are means ±SEM.</p

Correlation between serum antibody titers and immunity indices.

<p>Capital case–isoforms used for immunization; lower case–genotypes of the strains used for challenge.</p

Survival of immunized mice in response to bacterial challenge.

<p>Groups of 8 BALB/c mice that were immunized with Caf1_NT1 (A, D), Caf1_NT2 (B, E), or Caf1_NT3 (C, F) isoforms were challenged with <i>Y</i>. <i>pestis</i> strains producing different Caf1 isoforms: Caf1_NT1 (circles); Caf1_NT2 (squares); or Caf1_NT3 (triangles)), at high (2000 LD₅₀, panels A-C), or low (200 LD₅₀, panels D-F) doses. Survival was monitored for 21 days after the infection. *<i>P</i><0.05; **<i>P</i><0.01 (Log-rank Mantel-Cox test). The results have been acquired with n = 8 BALB/c for each dose of subcutaneous infection.</p