Abstract
Objective
We estimated the difference in mortality between mature male and female Vendace
Coregonus albula
based on a large data set of catch samples from 25 locations in Finland. We then ...used this estimate and age distribution data from Lake Etelä‐Konnevesi to illustrate how the sex ratio (females per one male) might decrease as the average age of spawners increases during a several‐year‐long period of recruitment failure.
Methods
We estimated mortalities first from sex‐specific age–ln(catch) curves and second from the average age‐specific proportions of different sexes.
Result
The estimate of the additional mortality of males was around 0.2–0.4, depending on the method of estimation, and assumed true proportions in the population at age 1 (two growing seasons), when Vendace reaches sexual maturity. When using the additional mortality estimate and age distribution data from Lake Etelä‐Konnevesi, the hypothetical sex ratio in the most extreme year was even as skewed as four females per one male.
Conclusion
If the lack of males per female spawner during a population decline reduces the per capita recruitment success of females, this is a depensatory density‐dependent effect, the Allee effect. This phenomenon may partly explain the rapid population collapses and contribute to 2‐year cyclicity typical of the dynamics of Vendace populations.
Impact statement
In the short‐lived coregonid fish Vendace, the mortality of males is considerably higher than that of females. During a period of low recruitment, this leads to a strongly skewed sex ratio, with female dominance in the spawning stock. Population decline accelerates if the increase in female dominance during stock decline reduces reproduction success (Allee effect). In stock assessment, attention should be paid to the sex ratio of the spawning stock, not just the spawner biomass.
BioImageXD puts open-source computer science tools for three-dimensional visualization and analysis into the hands of all researchers, through a user-friendly graphical interface tuned to the needs ...of biologists. BioImageXD has no restrictive licenses or undisclosed algorithms and enables publication of precise, reproducible and modifiable workflows. It allows simple construction of processing pipelines and should enable biologists to perform challenging analyses of complex processes. We demonstrate its performance in a study of integrin clustering in response to selected inhibitors.
Daily food intake of adult burbot, Lota lota, fed on vendace, Coregonus albula, were estimated experimentally at four different water temperatures (2.4, 5.1, 10.8 and 23.4°C). Mean daily food intake ...(MDI; g d^sup -1^) and relative daily food intake (RDI; g g^sup -1^ d^sup -1^) increased with temperature from 2.4 to 10.8°C and decreased at 23.4°C. Temperatures of maximum daily food intake values were 13.6°C for MDI and 14.4°C for RDI. No correlation between food intake values and burbot weight was observed. RDI values were used to estimate annual food consumption of burbot population. Annual food consumption estimates were 9.7kg ha^sup -1^ and 24.3kg ha^sup -1^ when burbot biomass was 2.0 or 5.0kg ha^sup -1^, respectively.PUBLICATION ABSTRACT
To evaluate the consistency of mobile and vertical echosounding results from the 1980s to the 2000s, fish density (fish ha
−1
) and target strength (TS, dB) estimates of single (70 and 200 kHz) and ...split (38 and 120 kHz) beam echo sounders were compared under varying light conditions. Acoustic estimates were compared with trawling results. During daytime hauls, the catch per swept area (CSA) of vendace and smelt were high at 10–15 m depth and low at 15–30 m depth. Around sunset, vendace and to some degree also smelt were concentrated at some meters above the thermocline. Around midnight, the CSA showed that smelt occupied higher water layers than vendace. Under different light conditions, both single and split beam echo sounders were in good agreement regarding the general level of fish density. In dusk and darkness, density estimates from echosounding and trawling as well as the TS-distribution between the single and split beam sounders were more consistent than those in daylight. We conclude that in boreal lakes single and split beam echosoundings outline, in comparable light conditions, consistent time series from the 1980s up to the year 2010. Darkness gives the best condition for estimating fish density and acoustic fish size.
We tested experimentally how the eggs of coregonid fish from the same parents develop at different incubation temperatures under natural long and climate change induced short winter conditions. The ...experimental scenarios simulating the water temperature in the spawning areas were constructed using a meteorological model including the climate change scenarios and a thermodynamic water quality model. Northern latitude stocks of vendace (
Coregonus albula
) and European whitefish (
Coregonus lavaretus
) had high flexibility in the egg developmental rates: the physiologically distinct temperature-dependent regulation of the ontogenetic steps during incubation caused over 3 months long hatching-to-feeding window to adjust the hatching and start of external feeding in optimal conditions. Survival of embryos and larvae did not differ between scenarios and even in the shortest winter scenario, the survival and growth rate of embryos and larvae was high. An among-family effect on the hatching time of the offspring was also observed. Our results showed that spring warming of the water already under the ice is the key cue to synchronize the hatching of coregonids close to the ice break-up period.
Viruses may persist on solid surfaces for long periods, which may contribute to indirect transmission. Thus, it is imperative to develop functionalized surfaces that will lower the infectious viral ...load in everyday life. Here, we have tested a plastic surface functionalized with tall oil rosin against the seasonal human coronavirus OC43 as well as severe acute respiratory syndrome coronavirus 2. All tested non-functionalized plastic surfaces showed virus persistence up to 48 h. In contrast, the functionalized plastic showed good antiviral action already within 15 min of contact and excellent efficacy after 30 min over 90% humidity. Excellent antiviral effects were also observed at lower humidities of 20% and 40%. Despite the hydrophilic nature of the functionalized plastic, viruses did not adhere strongly to it. According to helium ion microscopy, viruses appeared flatter on the rosin-functionalized surface, but after flushing away from the rosin-functionalized surface, they showed no apparent structural changes when imaged by transmission electron microscopy of cryogenic or negatively stained specimens or by atomic force microscopy. Flushed viruses were able to bind to their host cell surface and enter endosomes, suggesting that the fusion with the endosomal membrane was halted. The eluted rosin from the functionalized surface demonstrated its ability to inactivate viruses, indicating that the antiviral efficacy relied on the active leaching of the antiviral substances, which acted on the viruses coming into contact. The rosin-functionalized plastic thus serves as a promising candidate as an antiviral surface for enveloped viruses.IMPORTANCEDuring seasonal and viral outbreaks, the implementation of antiviral plastics can serve as a proactive strategy to limit the spread of viruses from contaminated surfaces, complementing existing hygiene practices. In this study, we show the efficacy of a rosin-functionalized plastic surface that kills the viral infectivity of human coronaviruses within 15 min of contact time, irrespective of the humidity levels. In contrast, non-functionalized plastic surfaces retain viral infectivity for an extended period of up to 48 h. The transient attachment on the surface or the leached active components do not cause major structural changes in the virus or prevent receptor binding; instead, they effectively block viral infection at the endosomal stage.
Aims/hypothesis
The Coxsackie and adenovirus receptor (CAR) is a transmembrane cell-adhesion protein that serves as an entry receptor for enteroviruses and may be essential for their ability to ...infect cells. Since enteroviral infection of beta cells has been implicated as a factor that could contribute to the development of type 1 diabetes, it is often assumed that CAR is displayed on the surface of human beta cells. However, CAR exists as multiple isoforms and it is not known whether all isoforms subserve similar physiological functions. In the present study, we have determined the profile of CAR isoforms present in human beta cells and monitored the subcellular localisation of the principal isoform within the cells.
Methods
Formalin-fixed, paraffin-embedded pancreatic sections from non-diabetic individuals and those with type 1 diabetes were studied. Immunohistochemistry, confocal immunofluorescence, electron microscopy and western blotting with isoform-specific antisera were employed to examine the expression and cellular localisation of the five known CAR isoforms. Isoform-specific qRT-PCR and RNA sequencing (RNAseq) were performed on RNA extracted from isolated human islets.
Results
An isoform of CAR with a terminal SIV motif and a unique PDZ-binding domain was expressed at high levels in human beta cells at the protein level. A second isoform, CAR-TVV, was also present. Both forms were readily detected by qRT-PCR and RNAseq analysis in isolated human islets. Immunocytochemical studies indicated that CAR-SIV was the principal isoform in islets and was localised mainly within the cytoplasm of beta cells, rather than at the plasma membrane. Within the cells it displayed a punctate pattern of immunolabelling, consistent with its retention within a specific membrane-bound compartment. Co-immunofluorescence analysis revealed significant co-localisation of CAR-SIV with zinc transporter protein 8 (ZnT8), prohormone convertase 1/3 (PC1/3) and insulin, but not proinsulin. This suggests that CAR-SIV may be resident mainly in the membranes of insulin secretory granules. Immunogold labelling and electron microscopic analysis confirmed that CAR-SIV was localised to dense-core (insulin) secretory granules in human islets, whereas no immunolabelling of the protein was detected on the secretory granules of adjacent exocrine cells. Importantly, CAR-SIV was also found to co-localise with protein interacting with C-kinase 1 (PICK1), a protein recently demonstrated to play a role in insulin granule maturation and trafficking.
Conclusions/interpretation
The SIV isoform of CAR is abundant in human beta cells and is localised mainly to insulin secretory granules, implying that it may be involved in granule trafficking and maturation. We propose that this subcellular localisation of CAR-SIV contributes to the unique sensitivity of human beta cells to enteroviral infection.
As a consequence of a local disagreement between commercial fishermen and local fishing-right owners, we estimated the size of a vendace (Coregonus albula) stock in a southern boreal lake in Finland ...in March 2000. We applied a mobile under-ice echo-survey and catch sampling from winter seining. The sounder with a tape recorder was placed in a shuttle and towed under ice from hole to hole with a rope. The mean fish density was 4270 fish ha–1. Vendace biomass was estimated to be ca. 36 tonnes. Commercial fishing started on a restricted scale after the completion of the assessment. The vendace yield was ca. 6 tonnes in the area during the remainder of the winter-seining season. The total winter seining catch amounted to ca. 40% of the initial vendace stock size in January 2000.
We analysed the spatial scale of synchrony in the inter-annual variation of vendace population indices from time-series of 21 Finnish lake basins. We detected significant positive correlation between ...lakes in the variation of abundance of young-of-the-year recruits, residuals of a density dependence model for recruitment, newly hatched larvae and spawning stocks. The spatial scale of correlation was typically 100—300 km and anisotropic, being shorter along the north—south vector of distance than along the east—west vector. The outcomes did not change when the data were restricted to rule out cases with a possibility of dispersal between populations. The scale and anisotropy structure of synchrony in mean temperature during the four week period after the local ice break date closely resembled that of the vendace population indices. Regionally correlated exogenous factors synchronise the recruitment variation either directly or perhaps also through environmentally induced synchrony in predator stocks. The effective scale of correlation for these factors, especially along the north—south axis, can be short if a large proportion of the prerecruit mortality occurs during a short period and the timing of this period at different latitudes varies by weeks due to differences in time of ice break and vendace hatching.
Eurasian perch (
Perca fluviatilis
) were sampled in April, from May to June and at the end of August to test whether the current season (i.e. feeding conditions) affects the fishes’ stomach size ...(i.e. volume and weight). A wide range of size data were analysed to reveal the relationship between fish size (length and weight) and stomach size. No significant differences in length-specific stomach volume or stomach weight were found in fish sampled at different times of the year. However, there were differences between seasons in the size of the stomach in relation to body weight, as length-specific body weight changes during the year because of the development of gametes and changes in nutritional status. Both stomach volume and weight grew obeying the power function up to about 20 cm in total length of perch. Yet, the growth was faster than that predicted by the cube law in relation to fish length, i.e. allometric. In larger fish, stomach growth decreased in relation to growth in length, and the relative weight of the stomach even decreased in the largest size class. These dynamics match well with the typical pattern of growth and ontogenic shift in diet from small invertebrates to fish. A non-proportional power function relationship was found between stomach weight and stomach volume.
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