Preliminary data on the variability of three microsatellite loci in Pacific <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> and Atlantic <Emphasis Type="Italic">G. morhua</Emphasis> cod (Gadidae)

Variability of microsatellite DNA loci Gmo3, Gmo34, and Gmo35 is studied in samples of Pacific cod Gadus macrocephalus and Atlantic cod G. morhua. The results show high values of identity of the samples within the North Pacific basin (0.9766–0.9924) and within the Northeast Atlantic basin (0.9580). Based on the pairwise assessment of genetic differentiation, the F _ST values are significantly different in all variants between the samples of Pacific and Atlantic cod (F _ST = 0.5235–0.6719, p < 0.001). Within the basins, the significant differences in the frequencies of main alleles are revealed in the loci Gmo3 and Gmo34 for the samples from the Pacific and Atlantic oceans, respectively.     

Mitochondrial DNA polymorphism of atlantic cod of the Barents and White seas

High level of intraspecific polymorphism of the mtDNA cytochrome b gene in the Atlantic cod Gadus morhua L. from the northeastern part of the species range (Barents and White seas) is detected. The absence of genetic differentiation between the samples from different areas of the Norwegian and Barents seas is shown, and the fact that these samples belong to the same population of Northeast Arctic cod is confirmed. Significant differences in the frequences of mitochondrial DNA haplotypes between the cod from the Barents and White seas, as well as from the northwestern part of the range, are found. The cod Gadus morhua kildinensis Derjugin, 1920 from Mogilnoye Lake and Gadus morhua marisalbi Derjugin, 1920 from the White Sea were revealed to have common haplotypes with the cod from the Barents Sea, confirming the recent origin of these forms from the Atlantic cod G. morhua.     

Specific features of spatial distribution of Pacific cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> in waters off the eastern coast of the northern Kuril Islands and the southern extremity of Kamchatka

Spatial distribution of Pacific cod Gadus macrocephalus inhabiting waters off the eastern coast of the northern Kuril Islands and the southern part of Kamchatka has been studied. It is shown that the redistributions of densities of the aggregation of cod during the year occur mainly within the area under consideration. The absence of considerable migrations of cod is related, in particular, to sufficient food availability of abundant hydrobionts: for small-sized groups of cod, the main food are juvenile wall-eyed pollack Theragra chalcogramma and, for medium-sized and large-sized groups, its adult individuals and also Atka mackerel Pleurogrammus monopterygius and squid Belonella borealis.     

Infestation of the Pacific cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> by the parasitic copepod <Emphasis Type="Italic">Haemobaphes diceraus</Emphasis> (Copepoda: Pennellidae) at the eastern coast of the northern Kuril Islands and Southeast Kamchatka

Material was collected in 1997–1999, 2002, and 2006 at the eastern coast of the northern Kuril Islands and at the southeastern extremity of Kamchatka. The prevalence of infection by the parasitic copepod Haemobaphes diceraus in the cod Gadus macrocephalus during the study period averaged 22.2%. The intensity of H. diceraus infection was up to 6 ind/fish, and it increased with decrease in the average and greatest body length of the cod. With increase in fish body length, the role of the fourth branchial arch as the attachment site of the parasite decreased and the importance of the second branchial arch increased. Pacific cod mainly become infected by H. diceraus at depths of 101–150 m. A sharp increase in the occurrence of chitinized remains of this parasite occurred in fish starting with the 41–45 cm size group. The death rate of infected cod up to 40 cm long was 14.3%.     

Temperature-dependent growth and behavior of juvenile Arctic cod (<Emphasis Type="Italic">Boreogadus saida</Emphasis>) and co-occurring North Pacific gadids

The thermal sensitivity of Arctic fish species is poorly understood, yet such data are a critical component of forecasting and understanding ecosystem impacts of climate change. In this study, we experimentally measured temperature-dependent growth and routine swim activity in the juvenile stage of two Arctic gadids (Arctic cod, Boreogadus saida and saffron cod, Eleginus gracilis) and two North Pacific gadids (walleye pollock, Gadus chalcogrammus and Pacific cod, Gadus macrocephalus) over a 6-week growth period across five temperatures (0, 5, 9, 16 and 20 °C). Arctic cod demonstrated a cold-water, stenothermic response in that there was relatively high growth at 0 °C (0.73 % day^?1), near-maximal growth at 5 °C (1.35 % day^?1) and negative impacts on activity, growth and survival at 16 °C. In contrast, saffron cod demonstrated a warmer-water, eurythermic response, and temperature had a positive effect on growth and condition beyond 16 °C. However, despite these distinct thermal responses, walleye pollock and Pacific cod grew 2–3 times faster than Arctic gadids across a relatively broad temperature range above 5 °C. These results, coupled with possible northward expansion by both Pacific cod and walleye pollock, suggest Arctic cod are highly vulnerable to continued climate change in the Arctic, especially in coastal areas of the Beaufort and Chukchi Seas where temperatures already exceed 14 °C in the summer growth period.     

Embryonic and early larval development of White Sea cod <Emphasis Type="Italic">Gadus morhua marisalbi</Emphasis> (Gadidae)

Embryonic and early larval development of White Sea cod Gadus morhua marisalbi are described. The study is conducted on live material obtained after spawning of fishes in the tanks and based on artificial insemination of eggs. Dynamics of contact and mobility properties of cells in vivo and in vitro (in cell culture) is assessed. Discrete chronological parameters of the morphogenetic movements are determined. Early ontogeny of the White Sea cod is very similar to that in G. morhua of the Northeast Atlantic. However, the former subspecies differs in larger egg diameter (on average, 1.50 mm), larger buoyancy (at a salinity up to 24.22‰), and a resistance to negative temperature (?1.8°C).     

Brief morphological characteristics of cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> (Gadidae) from coastal waters of the Komandor Islands

The results of the studies on morpho-biological characteristics of Pacific cod Gadus macrocephalus of Bering Island coastal waters (Komandor Islands) are presented. As assessed by several morphometric indices, the studied cod differs from the cod of the Bering Sea.     

New encounters in Arctic waters: a comparison of metabolism and performance of polar cod (<Emphasis Type="Italic">Boreogadus saida</Emphasis>) and Atlantic cod (<Emphasis Type="Italic">Gadus morhua</Emphasis>) under ocean acidification and warming

Oceans are experiencing increasing acidification in parallel to a distinct warming trend in consequence of ongoing climate change. Rising seawater temperatures are mediating a northward shift in distribution of Atlantic cod (Gadus morhua), into the habitat of polar cod (Boreogadus saida), that is associated with retreating cold water masses. This study investigates the competitive strength of the co-occurring gadoids under ocean acidification and warming (OAW) scenarios. Therefore, we incubated specimens of both species in individual tanks for 4 months, under different control and projected temperatures (polar cod: 0, 3, 6, 8 °C, Atlantic cod: 3, 8, 12, 16 °C) and PCO₂ conditions (390 and 1170 µatm) and monitored growth, feed consumption and standard metabolic rate. Our results revealed distinct temperature effects on both species. While hypercapnia by itself had no effect, combined drivers caused nonsignificant trends. The feed conversion efficiency of normocapnic polar cod was highest at 0 °C, while optimum growth performance was attained at 6 °C; the long-term upper thermal tolerance limit was reached at 8 °C. OAW caused only slight impairments in growth performance. Under normocapnic conditions, Atlantic cod consumed progressively increasing amounts of feed than individuals under hypercapnia despite maintaining similar growth rates during warming. The low feed conversion efficiency at 3 °C may relate to the lower thermal limit of Atlantic cod. In conclusion, Atlantic cod displayed increased performance in the warming Arctic such that the competitive strength of polar cod is expected to decrease under future OAW conditions.     

Occurrence of a gelatinous predator (<Emphasis Type="Italic">Cyanea capillata</Emphasis>) may affect the distribution of <Emphasis Type="Italic">Boreogadus saida</Emphasis>, a key Arctic prey fish species

Although the Arctic cod (Boreogadus saida) has a pan-Arctic distribution, little is known about its occurrence in near-shore waters where this species is the principal prey for seabirds, marine mammals and other fish. Published research describes the scyphomedusa Cyanea capillata as an Arctic cod predator, and this paper presents observations from long-term investigations using active hydroacoustics that suggest the Arctic cod avoided C. capillata in two small bays of Cornwallis Island (Canadian High Arctic archipelago). Distribution patterns in echograms suggested that features such as boundary layer fronts restricted jellyfish movements and Arctic cod were often abundant on the side of fronts where C. capillata were absent. Thus, habitat partitioning allowed Arctic cod to share habitat with its predator, albeit exceptions to this sharing occurred when jellyfish abundance was high and Arctic cod were displaced. Thus, if a warmer Arctic triggers an increase in C. capillata abundance, it is possible that small-scale aspects of Arctic cod distribution could be affected. This in turn could have significant ripple effects within the Arctic food web, an additional and previously unrecognized consequence of climate change.     

Population Structure of Pacific Cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> in the Southern Part of the Range Based on the Microsatellite Analyses

The population structure of Pacific cod Gadus macrocephalus in the southern part of the range and adjacent regions is studied on the basis of the results of microsatellite analyses. Collected data indicate heterogeneity of this species population within the studied area. According to the obtained F_ST values, Pacific cod from the waters of the Republic of Korea (Yellow Sea side) and northwestern part of the Sea of Okhotsk significantly differ from all other studied regions (Table 4). Significant differentiation was also revealed between samples from the waters of the Tatar Strait and all other regions except for South Kurils Pacific cod (both Sea of Okhotsk and Pacific Ocean sides). These two latter sample collections were similar to each other as well. A low level of differentiation was also shown for the Peter the Great Bay and the East Sea/Sea of Japan waters of the Republic of Korea.     

Genome-wide identification,systematic analysis and characterization of <Emphasis Type="Italic">SRO</Emphasis> family genes in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

SIMILAR TO RCD ONE (SRO) is a small plant-specific gene family, which play essential roles in plant growth and development as well as in abiotic stresses. However, the function of SROs in maize is still unknown. In our study, six putative SRO genes were isolated from the maize genome. A systematic analysis was performed to characterize the ZmSRO gene family. The ZmSRO gene family was divided into two groups according to the motif and intron/exon analysis. Phylogenetic analysis of them with other plants showed that the clades of SROs along with the divergence of monocot and dicot and ZmSROs were more closely with OsSROs. Many abiotic stress response and hormone-induced cis-regulatory elements were identified from the promoter region of ZmSROs. Furthermore, RNA-seq analysis indicated that SRO genes were widely expressed in different tissues and development stages in maize, and the expression divergence was also obviously observed. Analyses of expression in response to PEG6000 and NaCl treatment, in addition to exogenous application of ABA and GA hormones showed that the majority of the members display stress-induced expression patterns. Taken together, our results provide valuable reference for further functional analysis of the SRO gene family in maize, especially in abiotic stress responses.     

Population genetic analysis of Euro-Arctic polar cod <Emphasis Type="Italic">Boreogadus saida</Emphasis> suggests fjord and oceanic structuring

Polar cod, Boreogadus saida, is a key species in Arctic marine ecosystems; however, its genetic population structure is largely undescribed. The population genetic structure of 472 B. saida specimens among nine locations in the north-east Atlantic was revealed using 12 microsatellite loci. Pairwise F _ST comparisons showed significant population differentiation between B. saida sampled inside fjords in Svalbard and north-east Greenland, as compared to B. saida from the shelf. The observed genetic variation was not a function of isolation by distance, and it is speculated that B. saida populations inhabiting fjords may have become reproductively isolated from shelf-dwelling B. saida during the last post-glacial recolonization.     

Genetic associations between ADHD and dopaminergic genes (<Emphasis Type="Italic">DAT1</Emphasis> and <Emphasis Type="Italic">DRD4</Emphasis>) VNTRs in Korean children

It is well known that dopaminergic genes affect the development of attention deficit hyperactivity disorder (ADHD) in various populations. Many studies have shown that variable number tandem repeats (VNTRs) located within the 3′-untranslated region of DAT1 and in exon 3 of DRD4 are associated with ADHD development; however, these results were inconsistent. Therefore, we investigated the genetic association between two VNTRs and ADHD in Korean children. We determined the VNTRs using PCR. We examined genotype and allele frequency differences between the experimental and control groups, along with the odds ratios, using Chi square and exact tests. We observed a significant association between the children with ADHD and the control group in the 10R/10R genotype of DAT1 VNTRs (p?=?0.025). In addition, the 11R allele of DAT1 VNTRs showed a higher frequency in the control group than in the ADHD group (p?=?0.023). Also, the short repeat (without 11R) and long repeat alleles (including 11R) were associated with ADHD (p?<?0.05). The analysis of DRD4 VNTRs revealed that the 2R allele is associated with ADHD (p?=?0.025). A significant result was also observed in long and short repeats (p?<?0.05). Additionally, ADHD subtypes showed that the DRD4 VNTRs are associated with combined and hyperactive-impulsive subtype groups (p?<?0.05). Therefore, our results suggest that DAT1 VNTRs and DRD4 VNTRs play a role in the genetic etiology of ADHD in Korean children.     

Quantifying food web interactions in the North Pacific – a data-based approach

As part of its annual bottom-trawl survey program, the Alaska Fisheries Science Center (AFSC) has been collecting and analyzing the stomach contents of groundfish predators since 1981. Between 1981 and 2011, a total of 233,451 fish stomachs were collected and analyzed from the eastern Bering Sea, the Gulf of Alaska, and the Aleutian Islands large marine ecosystems; these data are now available online as AFSC’s Groundfish Trophic Interactions Database. Here, we discuss features of the survey and data to aid in the interpretation and use of this extensive dataset for the Alaska region. The primary fish sampled include walleye pollock (Gadus chalcogrammus), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and arrowtooth flounder (Atheresthes stomias), although 159 predator species have been included in the stomach content analysis. Prey length measurements are included for important commercial prey and can identify age or size classes of prey prior to their recruitment into fisheries and most other surveys. With these data, one can track time trends in growth, mortality, and prey composition as ecosystem indicators, and include food web interactions in fish stock assessments for ecosystem-based fisheries management.     

The effects of population density on the rate of growth,maturation, and productivity of the stock of the northeast Arctic cod <Emphasis Type="Italic">Gadus morhua morhua</Emphasis>

Multiterm dynamics of biomass, fishing mortality level, average weight of fish of various ages, and the rate of sexual maturation of cod Gadus morhua morhua of the northeastern Arctic population was considered. Hypotheses that explain a regular increase in the rate of cod growth and maturation were discussed. It was concluded that population density affects the rate of growth and the rate of sexual maturation of individuals.     

Genome-wide identification and expression analysis of sulphate transporter (<Emphasis Type="Italic">SULTR</Emphasis>) genes under sulfur deficiency in <Emphasis Type="Italic">Brachypodium distachyon</Emphasis>

Sulphur is an important mineral element for plant growth and development. It involves in a number of metabolic processes with crucial functions. This study has performed a genome-wide analysis of sulfate transporter (SULTR) genes in Brachypodium distachyon. Ten putative SULTR genes were identified in Brachypodium genome. BdSULTR genes included 6–17 exons encoding a protein of 647–693 residues with basic nature. BdSULTR proteins included both sulfate_transp (PF00916) and STAS (PF01740) domains. BdSULTRs were classified into 4 groups based on the phylogenetic distribution. Promoter regions of all BdSULTR genes, except for BdSULTR3;3 and 3;5 included the SURECOREATSULTR11 elements. A considerable structural overlap was identified between superimposed SULTR1;3 and 3;1 proteins, indicating that SULTR1 members may also involve in plant stress response/tolerance like SULTR3 members. Microarray and RNA-Seq analyses also revealed the differential expression of SULTR 1 and 3 genes under different biotic/abiotic stresses. Protein–protein interaction partners of BdSULTRs were mainly related with adenylyl-sulfate kinases, 5′-adenylylsulfate reductases, ATP sulfurylases, and acyl carrier proteins. Moreover, expression profiles of identified BdSULTR genes under S-deficiency were analyzed using RT-qPCR. It was revealed that BdSULTR1;1 and 3;1 are highly expressed in plant roots as ~tenfold and ~fivefold, respectively, while BdSULTR2 (~15-fold) and 3;1 (~twofold) are abundantly expressed in leaf tissues.     

Some issues related to reproduction of Pacific cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> in waters of the eastern coast of the northern Kuril Islands and the southern extremity of Kamchatka

The analysis of data collected in December 1996 and 1998 on the reproduction of cod Gadus macrocephalus in Pacific waters of the northern Kuril Islands and the southern part of Kamchatka was performed. It was shown that the individual absolute fecundity of the cod varies within 0.197–9.729 million eggs and the relative fecundity, in the range of 24-1386 eggs. The fecundity of 1000 mature females comprises 2179–2449 million eggs. The low individual fecundity of fish is related to pseudobranchial tumor growth. The main role in cod reproduction is played by females of two-three size groups characterized by the highest numbers of mature females. It is suggested that different fecundity within the range of Pacific cod is related to environmental conditions, in particular, water temperature in the spawning grounds during spawning rather than to the habitation latitude.