Spatial and Temporal Relations between Fluvial and Allacustrine Yellowstone Cutthroat Trout, Oncorhynchus clarki bouvieri, Spawning in the Yellowstone River, Outlet Stream of Yellowstone Lake

Yellowstone cutthroat trout (YCT), Oncorhynchus clarki bouvieri, that spawn in the outlet of Yellowstone Lake show two potamodromous migration patterns, fluvial and allacustrine. The main purpose of this study was to determine whether those fluvial and allacustrine YCT represent reproductively isolated stocks. Redd surveys indicated spawning occurred during about 5 consecutive weeks between late May and mid-July 1993–1995. Lake fish (N=6), defined as radiotagged YCT that entered Yellowstone Lake after the spawning period (i.e. allacustrine pattern), were found in the river between the lake outlet (river kilometer [Rkm] 0) and Rkm 20.0 during spawning. Probable lake fish (N=28; tagged YCT that were last detected near the lake outlet) were found between Rkm 0 and Rkm 22.5 during spawning. River fish (N=4; tagged YCT that remained in the river when annual tracking concluded in fall, i.e. fluvial pattern) were found between Rkm 1.1 and Rkm 18.0 during spawning. Fidelity to spawning areas used between consecutive years was suggested by one of five lake fish and the single river fish for which data were available. Spatial overlap in spawning and a lack of temporal separation between the life-history types during spawning suggested that fluvial and allacustrine YCT were not reproductively isolated. Radiotagging, as well as visual observations made annually from boats during April and May, indicated fluvial YCT overwintered downstream from Rkm 14 and were few, probably on the order of 10% of all YCT that spawned in the Yellowstone River.     

Early Marine Migration Patterns of Wild Coastal Cutthroat Trout (Oncorhynchus clarki clarki), Steelhead Trout (Oncorhynchus mykiss), and Their Hybrids

Background

Hybridization between coastal cutthroat trout (Oncorhynchus clarki clarki) and steelhead or rainbow trout (Oncorhynchus mykiss) has been documented in several streams along the North American west coast. The two species occupy similar freshwater habitats but the anadromous forms differ greatly in the duration of marine residence and migration patterns at sea. Intermediate morphological, physiological, and performance traits have been reported for hybrids but little information has been published comparing the behavior of hybrids to the pure species.

Methodology/Principal Findings

This study used acoustic telemetry to record the movements of 52 cutthroat, 42 steelhead x cutthroat hybrids, and 89 steelhead smolts, all wild, that migrated from Big Beef Creek into Hood Canal (Puget Sound, Washington). Various spatial and temporal metrics were used to compare the behavior of the pure species to their hybrids. Median hybrid residence time, estuary time, and tortuosity values were intermediate compared to the pure species. The median total track distance was greater for hybrids than for either cutthroat or steelhead. At the end of each track, most steelhead (80%) were located near or north of the Hood Canal, as expected for this seaward migrating species, whereas most cutthroat (89%) were within 8 kilometers of the estuary. Most hybrids (70%) were detected leaving Hood Canal, though a substantial percentage (20%) remained near the Big Beef Creek estuary. More hybrids (7.5%) than pure cutthroat (4.5%) or steelhead (0.0%) were last detected in the southern reaches of Hood Canal.

Conclusions/Significance

Given the similarity in freshwater ecology between the species, differences in marine ecology may play an important role in maintaining species integrity in areas of sympatry.     

Expression Patterns of HvCKX Genes Indicate Their Role in Growth and Reproductive Development of Barley

Cytokinin oxidase/dehydrogenase proteins (CKX) are encoded by a multigene family of CKX genes with a varying number of members depending on species. For some of the genes, spectacular effects on grain production in selected cereals have been observed. Despite the fact that partial or full length sequences of most HvCKX genes in barley (Hordeum vulgare) have already been published, in most cases their specific biological functions have not been reported. Detailed expression patterns for five HvCKX genes in different organs/tissues of developing barley plants coupled with analysis of RNAi silent for two genes are presented to test the hypothesis that these expression profiles might indicate their function. Elevated expression for four of them – HvCKX1, HvCKX9, HvCKX4, and HvCKX11 – was found in developing kernels of wild-type plants compared to other tissues. HvCKX5 was mainly expressed in leaf tissue. Lower expression was noted for HvCKX1 in seedling roots and for HvCKX9 in leaves. The documented effect of RNAi silencing of HvCKX1 and a trend for HvCKX9 was higher plant productivity, and the trait was inherited through four generations. Higher plant yield was determined by higher numbers of seeds and spikes. Increased productivity was significantly greater in HvCKX1 silenced plants showing higher relative expression of HvCKX1 in developing kernels of wild-type plants compared to the expression of HvCKX9. Both HvCKX1 silenced T₁ seedlings of cv. Golden Promise and the newly transformed breeding line STH7308 showed greater root mass, but this trait was not inherited in the next generation. Similarly HvCKX9 silenced T₁ seedlings exhibited greater plant height without inheritance in the next generation. It is suggested that these effects were not inherited because of compensation by other genes co-ordinately regulating reproductive development. One line with untypically changed, inherited phenotype, which was selected from several dozen silenced lines showing stable and common phenotypes is presented.     

Divergence in Expression of Candidate Genes for the Smoltification Process Between Juvenile Resident Rainbow and Anadromous Steelhead Trout

Rainbow and steelhead trout (Oncorhynchus mykiss), among other salmonid fishes, exhibit tremendous life history diversity, foremost of which is variation in migratory propensity. While some individuals possess the ability to undertake an anadromous marine migration, others remain resident in freshwater throughout their life cycle. Those that will migrate undergo tremendous physiological, morphological, and behavioral transformations in a process called smoltification which transitions freshwater-adapted parr to marine-adapted smolts. While the behavior, ecology, and physiology of smoltification are well described, our understanding of the proximate genetic mechanisms that trigger the process are not well known. Quantitative genetic analyses have identified several genomic regions associated with smoltification and migration-related traits within this species. Here we investigate the divergence in gene expression of 18 functional and positional candidate genes for the smoltification process in the brain, gill, and liver tissues of migratory smolts, resident parr, and precocious mature male trout at the developmental stage of out-migration. Our analysis reveals several genes differentially expressed between life history classes and validates the candidate nature of several genes in the parr-smolt transformation including Clock1α, FSHβ, GR, GH2, GHR1, GHR2, NDK7, p53, SC6a7, Taldo1, THRα, THRβ, and Vdac2.     

Effect of Hyperthermia on Proteases and Growth Regulators in the Skeletal Muscle of Cultivated Rainbow Trout O. mykiss

Russian Journal of Bioorganic Chemistry - The expression of some structural and regulatory muscle protein genes as well as the activity of the main intracellular proteases (calpains, proteasomes)...     

Introgression between Two Cutthroat Trout Subspecies with Substantial Karyotypic, Nuclear and Mitochondrial Genomic Divergence

The authors used allozymes encoded by nuclear genes and restriction enzyme analysis of mitochondrial DNA (mtDNA) to study secondary contact between westslope (Salmo clarki lewisi) and Yellowstone cutthroat trout (Salmo clarki bouvieri) in Forest Lake, Montana. Eleven diagnostic allozyme loci identified this as a random-mating hybrid swarm. No parental, first-generation hybrid or backcross genotypes were detected in the sample (N = 33), and genotype distributions at all the variable loci conform to binomial expectations. There is little linkage disequilibrium between the diagnostic loci, indicating that the nuclear genomes of the two subspecies are largely randomly associated. The allozymes and mtDNA give identical estimates of the proportional genetic contribution of each subspecies. Thus, males and females from both subspecies have contributed equally to this hybrid swarm. Although these subspecies have accumulated substantial genetic divergence between their nuclear (Nei's D = 0.34) and mitochondrial (2% sequence divergence) genomes, this has not resulted in a genetic barrier to exchange between them.     

Stable Expression of a Foreign Gene, Delivered by Gene Gun, in the Muscle of Rainbow Trout Oncorhynchus mykiss

We report the efficient delivery of a foreign gene into muscle of rainbow trout Oncorhynchus mykiss with a gene gun. The foreign gene was a reporter gene, chloramphenicol acetyltransferase (CAT). Two CAT-containing plasmids were used: pCMV-CAT, which contains cytomegalovirus immediate early promoter, and pSV2-CAT, which contains the simian virus 40 early promoter. All plasmids were introduced by particle bombardment using a gene gun. During the 90-day sampling period following bombardment, CAT was strongly and stably expressed in the muscle of all the fish bombarded with pCMV-CAT and pSV2-CAT. No CAT expression was detected in the blood samples until 90 days after introduction, when it was found in only one fish from the pCMV-CAT group and one from the pSV2-CAT group. The stable and long-term expression of plasmid DNA in muscle makes muscle an attractive target tissue for the introduction of viral DNA for the purpose of DNA vaccination. Received June 5, 1999; accepted November 2, 1999.     

Quorum-Sensing Genes in Pseudomonas aeruginosa Biofilms: Their Role and Expression Patterns

Acylated homoserine lactone molecules are used by a number of gram-negative bacteria to regulate cell density-dependent gene expression by a mechanism known as quorum sensing (QS). In Pseudomonas aeruginosa, QS or cell-to-cell signaling controls expression of a number of virulence factors, as well as biofilm differentiation. In this study, we investigated the role played by the las and rhl QS systems during the early stages of static biofilm formation when cells are adhering to a surface and forming microcolonies. These studies revealed a marked difference in biofilm formation between the PAO1 parent and the QS mutants when glucose, but not citrate, was used as the sole carbon source. To further elucidate the contribution of lasI and rhlI to biofilm maturation, we utilized fusions to unstable green fluorescent protein in concert with confocal microscopy to perform real-time temporal and spatial studies of these genes in a flowing environment. During the course of 8-day biofilm development, lasI expression was found to progressively decrease over time. Conversely, rhlI expression remained steady throughout biofilm development but occurred in a lower percentage of cells. Spatial analysis revealed that lasI and rhlI were maximally expressed in cells located at the substratum and that expression decreased with increasing biofilm height. Because QS was shown previously to be involved in biofilm differentiation, these findings have important implications for the design of biofilm prevention and eradication strategies.     

Morphology and Growth of Lateral Line Organs of the Rainbow Trout (Oncorhynchus mykiss)

Abstract The morphology and growth of selected lateral line organs of the rainbow trout (Oncorhynchus mykiss) are described. Canal neuromasts of the infraorbital and operculo–mandibular canal of three different–sized trout have been examined by light microscopy. The number of neuromasts and pores, as well as their distribution, is constant in all sizes of fish. However, the area and estimated number of hair cells (HC) of the examined neuromasts increase with size and with a correlation coefficient (r²) of 0.90 and 0.87, respectively. It was found that area and estimated hair cell number of neuromasts increase 6-fold in fish from 10 to 30 cm total length (TL). Based on calculation of the hair cell number in small and large fish, a net addition of 1 and 6 HC per day is suggested for IO and OM neuromasts, respectively.     

Transfection with Different Connexin Genes Alters Growth and Differentiation of Human Choriocarcinoma Cells

To examine the role of cell–cell communication via gap junctions in controlling proliferation and differentiation we transfected the malignant trophoblast cell line Jeg-3, which exhibits extremely low cell–cell communication mediated by endogenously expressed connexin40, with connexin26, connexin40, and connexin43, respectively.In vitrogrowth of all cell clones transfected with connexin genes was significantly reduced compared to controls. This effect corresponded to a significant increase in total junctional conductance of all clones. Single-channel conductances for channels formed by the transfected connexins were in the range of the values published previously. Though total junctional conductance varied highly among clones and even within one clone, differentiation of the cells indicated by β-hCG secretion was most prominent in the clones that revealed the largest amount of well-coupled cell pairs. Connexin26 channels enable cells of one clone to reduce drastically growth rate and produce significantly higher secretion of β-hCG. Connexin43 had only moderate effects on the differentiation properties of Jeg-3 cells. These findings suggest that restoration of cell–cell communication plays a role in growth reduction and in differentiation of tumor cells and that different channel proteins might have different effects.     

Identification of a Gene Regulating the Tissue Expression of a Phosphoglucomutase Locus in Rainbow Trout

Nine percent of the rainbow trout (Salmo gairdneri) from a hatchery source have a greater than 100-fold increase in expression of a phosphoglucomutase (PGM) locus, Pgm1, in the liver but have normal expression of this locus in other tissues. The results of genetic crosses are consistent with a single regulatory gene with additive inheritance being responsible for the differences in the amount of PGM activity in the liver.—The allele responsible for the expression of Pgm1 in the liver is apparently a recent mutation. This is supported by its restricted distribution in rainbow trout and the absence of liver Pgm1 expression in closely related species. This genetic system is valuable for future analysis of the control of gene expression and in determining the relative evolutionary importance of genetic variation at structural and regulatory genes.     

虹鳟鱼(Salmo grairdneri Richard)基因文库的构建及生长激素基因的克隆和亚克隆

以噬菌体EMBL3作为载体,构建了虹鳟鱼的全基因文库,制备了包装蛋白效率达4.6×10~8Pfu/μgDNA.基因文库重组噬菌的量为8.2×10~5pfu/μgDNA.同时用含虹鳟鱼生长激素基因cDNA的pAF-51△S作为探针,从该文库中筛选出两个阳性噬斑,复筛获得90％以上的阳性斑。并从阳性克隆中回收虹鳟收生长激素基因片段为6kb,亚克隆到puc-18质粒中,进行了酶切分析。     

猪背最长肌中肌肉生长和脂肪沉积相关基因的差异表达和主成分分析

骨骼肌细胞和脂肪细胞在分化生长速度上相对竞争的平衡点是猪肉质和胴体性状的决定因素.利用Oligo功能分类芯片检测了瘦肉型的长白猪和脂肪型的太湖猪在初生、1、2、3、4和5月龄间背最长肌中肌肉生长和脂肪沉积相关基因的动态表达变化.差异表达分析结果显示,在初生至5月龄的品种间分别有15、16、11、13、18和20个基因的表达差异倍数大于2倍.品种内的方差分析表明,长白猪分别有18和22个基因,太湖猪分别有3和7个基因在月龄间的表达差异达极显著(Ｐ<0.01)和显著水平(Ｐ<0.05).主成分分析结果显示,先降后升是两品种内最具代表性的基因表达模式,且长白猪和太湖猪分别有7和6个基因的表达模式明显偏离其他基因,提示其可能受到了重要的调控. 此外,5个差异表达基因的荧光定量RT-PCR验证结果均与芯片结果呈正相关趋势.以上结果筛选出了对于猪肉质和胴体性状可能具有重要影响,值得深入研究的一些候选基因,为深入研究生长发育过程中参与肌纤维生长和脂肪酸合成关键基因的表达变化规律和互作调控机制提供了基础数据.     

Lens-Specific Expression of PDGF-A Alters Lens Growth and Development

The vertebrate lens provides anin vivomodel to study the molecular mechanisms by which growth factors influence development decisions. In this study, we have investigated the expression patterns of platelet-derived growth factor (PDGF) and PDGF receptors during murine eye development byin situhybridization. Postnatally, PDGF-A is highly expressed in the iris and ciliary body, the ocular tissues closest to the germinative zone of the lens, a region where most proliferation of lens epithelial cells occurs. PDGF-A is also present in the corneal endothelium anterior to the lens epithelium in embryonic and early postnatal eyes. PDGF-B is expressed in the iris and ciliary body as well as in the vascular cells which surround the lens during early eye development. In the lens, expression of PDGF-α receptor (PDGF-αR), a receptor that can bind both PDGF-A and PDGF-B, is restricted to the lens epithelium throughout life. The expression of PDGF-αR in the lens epithelial cells and PDGF (A- and B-chains) in the ocular tissues adjacent to the lens suggests that PDGF signaling may play a key role in regulating lens development. To further examine how PDGF affects lens developmentin vivo,we generated transgenic mice that express human PDGF-A in the lens under the control of the αA-crystallin promoter. The transgenic mice exhibit lenticular defects that result in cataracts. The percentage of surface epithelial cells in S-phase is increased in transgenic lenses compared to their nontransgenic littermates. Higher than normal levels of cyclin A and cyclin D2 expression were also detected in transgenic lens epithelium. These results together suggest that PDGF-A can induce a proliferative response in lens epithelial cells. The lens epithelial cells in the transgenic mice also exhibit characteristics of differentiating fiber cells. For example, the transgenic lens epithelial cells are slightly elongated, contain larger and less condensed nuclei, and express fiber-cell-specific β-crystallins. Our results suggest that PDGF-A normally acts as a proliferative factor for the lens epithelial cellsin vivo.Elevated levels of PDGF-A enhance proliferation, but also appear to induce some aspects of the fiber cell differentiation pathway.     

Divergent Evolutionary and Expression Patterns between Lineage Specific New Duplicate Genes and Their Parental Paralogs in Arabidopsis thaliana

Gene duplication is an important mechanism for the origination of functional novelties in organisms. We performed a comparative genome analysis to systematically estimate recent lineage specific gene duplication events in Arabidopsis thaliana and further investigate whether and how these new duplicate genes (NDGs) play a functional role in the evolution and adaption of A. thaliana. We accomplished this using syntenic relationship among four closely related species, A. thaliana, A. lyrata, Capsella rubella and Brassica rapa. We identified 100 NDGs, showing clear origination patterns, whose parental genes are located in syntenic regions and/or have clear orthologs in at least one of three outgroup species. All 100 NDGs were transcribed and under functional constraints, while 24% of the NDGs have differential expression patterns compared to their parental genes. We explored the underlying evolutionary forces of these paralogous pairs through conducting neutrality tests with sequence divergence and polymorphism data. Evolution of about 15% of NDGs appeared to be driven by natural selection. Moreover, we found that 3 NDGs not only altered their expression patterns when compared with parental genes, but also evolved under positive selection. We investigated the underlying mechanisms driving the differential expression of NDGs and their parents, and found a number of NDGs had different cis-elements and methylation patterns from their parental genes. Overall, we demonstrated that NDGs acquired divergent cis-elements and methylation patterns and may experience sub-functionalization or neo-functionalization influencing the evolution and adaption of A. thaliana.