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Until recently, the Kara Sea was a stable ecosystem unaffected by alien species invasions. However, at the beginning of the twenty-first century, the snow crab (Chionoecetes opilio) was detected. Studies conducted between 2013 and 2022 in Blagopoluchiya Bay (Novaya Zemlya Archipelago, Kara Sea) provided an opportunity to observe the establishment of a population of this species and its influence on benthic communities. Various sampling methods, such as trawl and grab surveys, as well as video observations, were used to study two main seabed habitats, one in the deep inner basin and the other at the sill at the bay's exit. The study revealed significant changes in benthic ecosystems, including declines in integral benthic characteristics such as abundance, biomass, diversity, and shifts in dominant species. The response of megabenthos and macrobenthos varied between habitats, but in general, there was a sharp decline in the abundance of large bivalves and brittle stars. The observed changes were not related to environmental variability but most likely to the abundance and size structure of the snow crab. The taxonomic and size structure of the benthos changed as crab individuals increased in size, and the changes were faster and more pronounced in the area with higher crab abundance. These findings raise concerns about the potential long-term effects of the snow crab invasion on the Kara Sea ecosystem, including reduced biodiversity and changes in food webs. [ABSTRACT FROM AUTHOR]

The snow/pink crab (Chionoecetes opilio) and Northern shrimp (Pandalus borealis) are widely distributed in the North Atlantic Ocean. During processing/consumption, about 80% of the harvest is discarded as processing waste, which is a rich source of protein, chitin, minerals, and carotenoids. This study, for the first time, investigated the proximate composition and individual amino acids, minerals, and carotenoids from different body parts (carapace, shoulder, claw, tip, and leg) of snow crabs and shrimp shells. Shrimp proteins were found to be abundant and well-balanced in their amino acid composition. Compared to shrimp shells, a lower content of amino acids was found in the snow crab, depending on the part of the shell used. Moreover, crab shells, mainly crab claws, contained a higher (p < 0.05) level of chitin compared to shrimp shells. Seven micro-elements (Mn, Fe, Cu, Zn, As, Ba, and Ce) and six macro-elements (Ca, Na, K, Mg, P, and Sr) were identified using inductively coupled plasma-mass spectrometry (ICP-MS). Among them, calcium and iron were higher in crab carapaces (p < 0.05), followed by shrimp shells and other crab shell segments. Additionally, shrimp and crab carapaces contained a significant level of carotenoids, and these were mainly composed of astaxanthin and its mono- and diesters, along with zeaxanthin, astacene, canthaxanthin, and lutein. Thus, this investigation provides detailed information to allow upcycling of shellfish waste and addresses the knowledge gap concerning the availability of various nutrients in different crab sections and shrimp shells. [ABSTRACT FROM AUTHOR]

The snow/pink crab (Chionoecetes opilio) and Northern shrimp (Pandalus borealis) are widely distributed in the North Atlantic Ocean. During processing/consumption, about 80% of the harvest is discarded as processing waste, which is a rich source of protein, chitin, minerals, and carotenoids. This study, for the first time, investigated the proximate composition and individual amino acids, minerals, and carotenoids from different body parts (carapace, shoulder, claw, tip, and leg) of snow crabs and shrimp shells. Shrimp proteins were found to be abundant and well-balanced in their amino acid composition. Compared to shrimp shells, a lower content of amino acids was found in the snow crab, depending on the part of the shell used. Moreover, crab shells, mainly crab claws, contained a higher (p < 0.05) level of chitin compared to shrimp shells. Seven micro-elements (Mn, Fe, Cu, Zn, As, Ba, and Ce) and six macro-elements (Ca, Na, K, Mg, P, and Sr) were identified using inductively coupled plasma-mass spectrometry (ICP-MS). Among them, calcium and iron were higher in crab carapaces (p < 0.05), followed by shrimp shells and other crab shell segments. Additionally, shrimp and crab carapaces contained a significant level of carotenoids, and these were mainly composed of astaxanthin and its mono- and diesters, along with zeaxanthin, astacene, canthaxanthin, and lutein. Thus, this investigation provides detailed information to allow upcycling of shellfish waste and addresses the knowledge gap concerning the availability of various nutrients in different crab sections and shrimp shells.

We report the complete mitochondrial genome of a hybrid snow crab between a female Chionoecetes opilio and male C. japonicus. The circular genome was 16,065 bp in length, and consisted of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. The composition and arrangement of its complete mitochondrial genome were very similar to that reported for the maternal species, C. opilio. The close genetic relationship is reflected in the phylogenetic tree and supports maternal inheritance patterns.

The quantity of snow crabs (Chionoecetes opilio) harvested in Korea is subject to seasonal restrictions; therefore, snow crabs are imported from Russia. Metabolites in snow crabs from two geographic origins were compared. The metabolites were subjected to metabolomic analysis to prevent fraudulent sales of marine products from a particular country. Capillary electrophoresis time-of-flight mass spectrometry was used. Seventy-seven target metabolites were identified using a mass spectral library. Through orthogonal partial least squares discriminant analysis, the top 25 biomarker candidates were evaluated based on p -values and fold changes. A total of 246 peaks (187 and 59 in the cation and anion modes, respectively) were identified. Among the biomarker candidates, 2-oxovaleric acid, asymmetric dimethylarginine, hypotaurine, and allo-threonine were selected as final biomarkers to unequivocally determine the geographic origin. Overall, metabolic analyses allowed us to differentiate snow crabs from different geographic origins. This method could also be extended of other marine products. [Display omitted] • Metabolomics revealed distinct characteristics of Korean and Russian snow crabs. • 2-Oxoisovaleric acid best explained differences in snow crabs between two regions. [ABSTRACT FROM AUTHOR]

The snow crab (Chionoecetes opilio) fishery has great economic importance for Nova Scotia, contributing $263 million to fisheries and more than one-fifth of Canadian snow crab revenues in 2021. Being a stenothermic species, snow crabs can only live within a narrow range of temperatures between −1 to 6 °C. The Scotian Shelf holds the southernmost populations of snow crab in the Atlantic and snow crab catch-per-unit-area (CPUA) in the Scotian Shelf. Trawl survey data from Ocean, because these cold-temperature requirements are a limiting factor for its distribution. This study investigates the relationship between bottom ocean temperature Fisheries and Oceans Canada from 2012 to 2021 were used. Through nonlinear modelling, CPUA (mt/km2) was regressed with respect to bottom ocean temperature along Northwest Atlantic Fisheries Organization divisions N-ENS, CFA 23, CFA 24, and CFA. The temperature-vs-CPUA relationship was unimodal for all studied years. The best-fit models explained a limited amount of variation, but CPUA consistently decreased to zero towards the highest recorded temperatures. Due to the ongoing global warming, bottom ocean temperatures across the Scotian Shelf will likely continue to increase, which thus might harm the Scotian Shelf snow crab fishery. In conclusion, this study underscores the potential impact of global warming on the economically significant snow crab fishery in the Scotian Shelf. The findings serve as a critical alert to the possible consequences of rising ocean temperatures, thereby contributing to our understanding and preparation for the future of marine ecosystems and industries. • Data were used from snow crab trawl surveys conducted along the Scotian Shelf off Nova Scotia, Canada, from 2012 to 2021. • Attributes of location, timestamp, bottom ocean temperature, snow crab biomass, and trawled surface area were considered. • Catch Per Unit Area (CPUA) in mt/km2 was regressed with respect to temperature. • CPUA decreased towards high temperatures in the Scotian Shelf for all studied years. [ABSTRACT FROM AUTHOR]

Macro- and meiobenthos of the Blagopoluchiya Bay (Novaya Zemlya, Kara Sea) have undergone significant changes in their quantitative distribution from 2013 to 2020. During this period, meiobenthos abundance has increased greatly, whereas macrobenthos abundance has decreased. Mean meiobenthos density has tripled (from 702 to 2293 ind./10 cm2), while mean macrobenthos density decreased by more than a half (from 1530 to 645 ind./m2). The observed growth of meiobenthos density was mainly due to an increase in the abundance of free-living nematodes. We suggest that the invasion of snow crab Chionoecetes opilio is one of the most important drivers of changes in benthos distribution. Following the crab invasion, there was a reduction of macrobenthic density and biomass and a compensatory increase in those in meiobenthos in the Blagopoluchiya Bay. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of Chionoecetes opilio is a 16,067 bp long, circular molecule which contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). Its gene contents and organization are generally similar to other majoid mitogenomes. However, the mitogenome shows unique characteristics; long terminal amino acids, loss or addition of 3 PCGs, a 1216 bp long putative D-loop region, and peculiar secondary structures of 5 tRNAs. The concatenated amino acid sequences of 13 PCGs were used to analyze the phylogenetic tree, which well supported the monophyly of brachyuran clades of Majoidea, Heterotremata, Thoracotremata, and Eubrachyura.

Expanding human activities alongside climate change, the introduction of invasive species and water contamination pose multiple threats to the unique marine ecosystems of the Pechora Sea in the Russian Arctic. Baseline data on biodiversity and responses to environmental change are urgently needed. Benthic decapod crustaceans are globally distributed and play an important role in fisheries, yet their roles in food webs are less understood. In this study, we used an integrated approach combining stomach content analysis and stable isotope analyses (δ13C and δ15N) to examine the trophic niches of three decapod species in the Pechora Sea including the invasive snow crab Chionoecetes opilio and two species of native decapods, the spider crab Hyas araneus and the hermit crab Pagurus pubescens. Stomach contents of 75 decapods were analysed (C. opilion = 23; H. araneusn = 9; P. pubescensn = 43), and 20 categories of prey items were identified with the most frequently occurring prey items being bivalve molluscs (Ciliatocardium ciliatum, Ennucula tenuis, Macoma calcarea), polychaetes, crustaceans and plant debris. Bayesian ellipse analyses of stable isotope signatures (n = 40) revealed that C. opilio displays an overlapping trophic niche with the two native decapods, providing direct evidence that the invader likely competes for food resources with both H. araneus and P. pubescens. As such, the presence of this invasive species could hold important consequences for trophic interactions, benthic ecosystem functioning and biodiversity. Microplastics were also found to be a likely stressor on this ecosystem, as 28% of all stomachs contained digested microplastics among other items. Long-term studies of benthic ecosystem structure and functioning are now needed to more fully understand the extent to which this new competitor may alter the future biodiversity of the Pechora Sea alongside the additional stressor of digested plastics. [ABSTRACT FROM AUTHOR]

This study investigated the behaviour and commercial catchability of snow crab (Chionoecetes opilio) in response to different low-powered LED lights under laboratory and field conditions. We created a novel choice-experiment in a laboratory setting in which we investigated the behaviour of snow crab in response to coloured LED lights. The results showed that snow crab movement was dependent on light colour, with animals choosing to move toward blue and white lights, away from purple lights, and no detectable effect for green and red lights. We then conducted two field experiments to investigate the effect of the same LED lights on the catch rates of commercial traps during the 2016 snow crab fishery on the east coast of Newfoundland and Labrador. Results from the first field experiment showed that adding white and purple LED lights into baited traps significantly improved Catch Per Unit Effort (CPUE) by 77% and 47% respectively. Results from the second field experiment showed that unbaited traps equipped with only LED lights (no bait), could also catch snow crab in comparable amounts to traditional baited traps, with soak time and depth explaining some of the variation in CPUE. Taken together, these experiments suggest that fishing enterprises can improve their catching performance and profitability by adding LED lights to their traps, or by using LED lights as a bait replacement.

The snow crab (Chionoecetes opilio) is one of the most important commercial crabs in the world; it is heavily exploited in Atlantic Canada, Alaska, the Sea of Japan and the Barents Sea. Catches in the Barents Sea north of Norway have increased dramatically in the last decade. Most of the world's catch is processed, frozen and exported overseas. However, recently there has been considerable interest in exporting live snow crab, particularly in Norway. The stress of capture and live transport can result in significant mortalities. In order to establish a live export industry for snow crab, the welfare of the animal must be monitored throughout all the steps of the live transport process. In this study the reactions of snow crabs exposed to increasing periods of air exposure were measured in terms of reflex indicators, incidence of mortality, blood lactate levels and blood protein and haemocyanin. Although this is not a specific live holding or live transport process the aim was to test the suitability of reflex indicators to reflect vitality (stress) and not just to predict mortality. This would be compared with traditional blood biochemistry techniques for measuring crustacean stress. The study demonstrated that the reflex index score (RIS) is suitable to assess the vitality of snow crab. Longer air exposure periods render higher mortality rates and less vital individuals. The authors believe using vitality reflex indicators would be a suitable way of measuring crab welfare during the live holding and transport process. [ABSTRACT FROM AUTHOR]

In this study, the effects of feeding (F) and starvation (S) on survival, injury, and weight of captive male snow crab were examined. The experiment was carried out with three replicates of each treatment. Each replicate had 11 individually tagged crabs (average weight of 650 g ± 37 SE) per tank (replicate) in a total of six circular tanks (500 L), with stocking densities of 14 kg/m. The experiment ran for 100 days and the animals were exposed to ambient seawater temperatures ranging from 4.4ºC to 5.4ºC during the trial period. There were no significant differences in wet weight between the groups at the start or at the end of the experiment. However, the hepatopancreas index (HI) significantly decreased in both groups from 6.1% at the start to, respectively, 4.6% (F) and 3.2% (S) at day 100. The S group had a significantly lower HI than the F group. Only one animal died during the experiment (day 100, F). The frequencies of injuries were similar in all groups. The results show that adult male snow crab can be stored for minimum 100 days (with or without feeding) with relatively low risk of physical injury, or mortality due to social interactions. [ABSTRACT FROM AUTHOR]

• We developed a high-resolution spatiotemporal state-space model for the snow crab (Chionoecetes opilio) population in the Eastern Bering Sea (EBS). • The model was used to refine the representation of spatial processes in integrated population models, facilitate understanding of the drivers of spatiotemporal population dynamics, and provide new insights for management advice. • The model implicitly accounts for seasonal movement between the time of the survey and that of fishery to estimate fine-scale spatial population dynamic and fishing impacts, including potential environmental drivers. • We quantify spatiotemporal variation in exploitable abundance, fishing mortality, recruitment, and mature and immature abundance. • The model estimated declines in exploitable abundance and in fishing mortality with variable spatial distributions, and sporadic recruitment, spatially concentrated in the northeast EBS. Considering spatial processes in population dynamics models can be difficult because of data limitations and computational costs. We adapted a high-resolution spatiotemporal assessment framework to better address fine-scale spatial heterogeneities based on theories of fish population dynamics and spatiotemporal statistics. Specifically, we developed a size-based state-space model for the snow crab (Chionoecetes opilio) population in the Eastern Bering Sea (EBS) to refine the representation of spatial processes in integrated population models, facilitate understanding of the drivers of spatiotemporal population dynamics, and provide new insights for management advice. The model fits to spatial survey and fishery-dependent catch data. It implicitly accounts for seasonal movement between the time of the survey and that of fishery to estimate fine-scale spatial population dynamic and fishing impacts, including potential environmental drivers. We quantify, for the first time, spatiotemporal variation in exploitable abundance, fishing mortality, recruitment, and mature and immature abundance. The model estimated declines in exploitable abundance and in fishing mortality with variable spatial distributions, and sporadic recruitment, spatially concentrated in the northeast EBS. Few spatial assessments have been used as the basis for management advice and we consider this study as a step towards the integration of spatial dynamics in stock assessment. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of Chionoecetes opilio is a 16,067 bp long, circular molecule which contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). Its gene contents and organization are generally similar to other majoid mitogenomes. However, the mitogenome shows unique characteristics; long terminal amino acids, loss or addition of 3 PCGs, a 1216 bp long putative D-loop region, and peculiar secondary structures of 5 tRNAs. The concatenated amino acid sequences of 13 PCGs were used to analyze the phylogenetic tree, which well supported the monophyly of brachyuran clades of Majoidea, Heterotremata, Thoracotremata, and Eubrachyura. [ABSTRACT FROM AUTHOR]

Milky hemolymph syndrome (MHS) has been observed in both reared and wild populations of the snow crab Chionoecetes opilio from the Sea of Japan. The virus presumably associated with MHS and detected with electron microscopy was designated ' Chionoecetes opilio bacilliform virus' ( CoBV), but little is known about its infectivity or pathogenicity in the snow crab. In this study, we performed an infectivity experiment in which snow crabs were injected with a viral inoculum prepared from MHS-affected crabs and then maintained at 2 °C or 2-8 °C. Cumulative mortality increased more rapidly at 2 °C than at 2-8 °C, reaching approximately 80% in both groups at the termination of the experiment. This result demonstrates the temperature-dependent pathogenicity of CoBV in the snow crab. CoBV-infected crabs displayed the clinical and histopathological signs of MHS. Mortality tended to increase as the viral load in the hemolymph increased at both 2 °C and 2-8 °C. The viral load in the hemolymph was significantly higher in dead crabs than in surviving crabs and was also elevated in various other organs. We conclude that CoBV is the causative agent of MHS and that severely affected crabs develop viremia that leads to death. [ABSTRACT FROM AUTHOR]

A nonlinear thermodynamic Sharpe-Schoolfield-Ikemoto (SSI) model has been applied to temperature-dependent development of some arthropods and other ectotherms. The most important parameter estimated by the SSI model is the intrinsic optimum temperature (Φ), which is the temperature at which the probability of an enzyme being in its active state is maximal. It has been also suggested that Φ authentically represents the optimal ambient temperature for fitness in ectotherms. We applied the SSI model to larvae of four aquatic decapod crustacean species distributed in cold, temperate, and tropical waters for understanding thermal adaptation in decapods. As a result, TΦ's estimates for the larvae corresponded to the optimum temperatures for larval survival/growth. The estimates also changed in accordance with the geographical distribution of the stages, species, and populations studied, i.e., 6.91-9.06 °C for cold-water species and 19.68-27.00 °C for temperate and tropical species. It would be useful to examine the relationship between changes in geographical distribution with temperature Φ and population size for a better understanding of population fluctuations under global climate change. Additionally, stable aquaculture production could be enhanced if the temperature conditions of each life history stage were controlled at Φ. [ABSTRACT FROM AUTHOR]

In this study the effects of different stocking densities on survival, injury and weight of captive male snow crab were examined. The first experiment (I) was carried out in square plastic tanks (700 L) with stocking densities of 100 (L), 150 (M) and 200 kg m−3 (H) for 30 days. In a second experiment (II) snow crabs were kept at a stocking density of 50 kg m−3 and were either fed (F) or not fed (S) for the same period of 35 days. The last experiment (III), was carried out with stocking densities of 25 kg m−3 for 21 days with two groups, one with inactivated claw and one without rubber bands, with three replicates per treatment. In the first experiment mortality (H = 27, M = 26 and L = 36%) and occurrence of injuries (H = 27, M = 20 and L = 16%) were high in all groups. The weight loss during the experimental period was; H = 15.3, M = 10.9 and L = 15.5 g, and was not significant different between the groups. In experiment II the mortality (F = 13% and S = 14%) and injuries were lower (F = 12% and S = 17%). The average weight increased in the fed treatment and decreased in the starved treatments. In the last experiment there was no mortality in any of the groups and the levels of injury were low (5% and 7%). The results show that adult male snow crab cannot be stored at densities equal to or higher than 25 kg m−3 for 3 weeks without risk of mortality. [ABSTRACT FROM AUTHOR]

Growth and moulting of wild-born immature snow crabs (Chionoecetes opilio (Fabricius, 1788)) were investigated by laboratory culture experiments. Crabs with 16.2-42.9 mm carapace width caught from the Sea of Japan were cultured at a temperature of their natural habitat (approximately 1°C). The growth indices (size increments at moulting in mm and in % of premoult carapace width) and intermoult period were significantly affected by premoult carapace width, but sex did not affect these variables. Furthermore, we demonstrated that premoult carapace width and days after moulting significantly affected moulting probability and we developed a moulting probability model based on these variables. From this model, the number of days of intermoult periods when moults occurred in 50% of crabs of instars VI, VII and VIII was estimated at 234, 284 and 346 days, respectively. [ABSTRACT FROM AUTHOR]

The food consumption pattern in megalopae of the snow crab Chionoecetes opilio (Fabricius, 1788) was investigated in the laboratory. Ten megalopae were individually cultured and given an excess of Artemia nauplii each day. All megalopae moulted into first-instar crabs 28-34 days after metamorphosis. The mean total number and total weight of Artemia consumed during the megalopal stage were 1920 individuals and 5.2 mg, respectively. Hence, the food requirement of snow crab megalopae was estimated as ~190% of the dry body weight of the first-instar crab. Initially, the number of Artemia consumed was nearly constant or decreased only slightly but, later, Artemia consumption decreased with development days. Two-segmented regressions provided good fits to the relationship between the number of days after metamorphosis and the cumulative number of Artemia consumed by individual megalopae. The mean value of the time after metamorphosis of the breakpoint in the rate of food consumption was estimated as 69% of the stage duration, which corresponds to the intermediate of late premoult. Crab sizes (carapace width, wet and dry body weight) were not significantly dependent on the number of Artemia consumed during the entire megalopal period although a positive correlation between these variables was observed. These results provide useful information on the appropriate feeding schedule and management practice for culturing snow crab megalopae and contribute to the understanding of megalopal growth efficiency to the first-instar crab in their natural habitat. [ABSTRACT FROM AUTHOR]

Fish and invertebrates that are unintentionally captured during commercial fishing operations and then released back into the ocean suffer mortality at unknown rates, introducing uncertainty into the fishery management process. Attempts have been made to quantify discard mortality rates using reflex action mortality predictors or RAMP which use the presence or absence of a suite of reflexes to predict discard mortality. This method was applied to snow crab, Chionoecetes opilio, during the 2010-2012 fisheries in the Bering Sea. Discard mortality in the fishery is currently assumed to be 50% in stock assessment models, but that rate is not based on empirical data and is widely recognized to be in need of refinement. Over 19 000 crab were evaluated using the RAMP method. The estimated discard mortality rate was 4.5% (s.d. = 0.812), significantly below the rate used in stock assessment models. Predicted discard mortality rates from the 2010 to 2012 study were strongly correlated with the air temperature at the St Paul Island airport in the Pribilof Islands. Using this relationship, the discard mortality rate from 1991 to 2011 was estimated at 4.8% (s.d. = 1.08). [ABSTRACT FROM AUTHOR]

The snow crab population in the eastern Bering Sea is panmictic, but it is spatially structured by inferred ontogenetic migrations, and fishing pressure is often spatially restricted by sea ice. This spatial structure is ignored when stock assessments are conducted, yet it is unclear if this omission influences management outcomes. We describe a process for evaluating the influence of spatial structure on the performance of stock assessments. This involves developing a spatial model which includes spatially explicit trends in recruitment, fishing mortality and rates of movement. The model is over-parameterized but provides good fits to the data for snow crab. It was used to simulate data sets to test the ability of a non-spatially structured (aggregate) assessment method in terms of estimating trends in abundance and fishing pressure in the presence of spatial structure. The aggregate assessment method performed well if survey selectivity was well known, but was unable to reliably represent the dynamics of the population without data on survey selectivity. Additional data on movement from tagging studies or winter surveys would be useful to improve the understanding of the influence of spatial structure on snow crab in the eastern Bering Sea. [ABSTRACT FROM AUTHOR]

Hematodinium is a parasitic dinoflagellate of numerous crustacean species, including the economically important Atlantic snow crab, Chionoecetes opilio. The parasite was cultured in vitro in modified Nephrops medium at 0°C and a partial characterization of the life stages was accomplished using light and transmission electron microscopy (TEM). In haemolymph from heavily infected snow crabs two life stages were detected; amoeboid trophonts and sporonts. During in vitro cultivation, several Hematodinium sp. life stages were observed: trophonts, clump colonies, sporonts, arachnoid sporonts, sporoblasts and dinospores. Cultures initiated with sporonts progressed to motile dinospores; however, those initiated with amoeboid trophonts proliferated, but did not progress or formed schizont-like stages which were senescent artefacts. Plasmodial stages were associated with both trophonts and sporonts and could be differentiated by the presence of trichocysts on TEM. Macrodinospores were observed but not microdinospores; likely due to the low number of Hematodinium sp. cultures that progressed to the dinospore stage. No early life stages including motile filamentous trophonts or gorgonlocks were observed as previously noted in Hematodinium spp. from other crustacean hosts. All Hematodinium sp. life stages contained autofluorescent, membrane-bound electron dense granules that appeared to degranulate or be expelled from the cell during in vitro cultivation. [ABSTRACT FROM PUBLISHER]