Gender identification of shovelnose sturgeon using ultrasonic and endoscopic imagery and the application of the method to the pallid sturgeon

Monthly sampling of shovelnose sturgeon Scaphirhynchus platorynchus , a biological surrogate for the endangered pallid sturgeon Scaphirhynchus albus , was conducted to develop a multi‐seasonal profile of reproductive stages. Data collected included histological characteristics of gonads from wild caught fish and laboratory and field ultrasonic and endoscopic images. These data were used to compare effectiveness of ultrasonic and endoscopic techniques at identifying gender of adult shovelnose sturgeon at different reproductive stages. The least invasive method ( i.e . ultrasound) was least effective while the most invasive ( i.e . endoscope through an abdominal incision) was the most effective at identifying shovelnose sturgeon gender. In most cases, success rate for identifying males was greater than females, with success at identifying both genders greater in more advanced reproductive stages. Concomitantly, for most months average reproductive stage was more advanced for males than females. April and May were the months with the most advanced reproductive stage, and were the months when ultrasound was most effective. Methods were also applied in the Upper Missouri River to validate their use on pallid sturgeon Scaphirhynchus albus . Ultrasound was successful at identifying pallid sturgeon gender, however, endoscopic examination through the urogenital duct was only successful at identifying pallid sturgeon gender when the urogenital duct was not opaque.     

圈养东北虎血液生理参数的测定

东北虎(Panthera tigris altaica)是一种淑临灭绝的食肉动物,现已被列入IUCN濒危物种红色名录(Goodrich et al.,2015)。东北虎主要分布于俄罗斯远东地区、中国东北地区和朝鲜的北部(Kitchener et al.,2017)。根据中俄边境地区的野生东北虎数量调查统计,该地区生存着成年老虎39只和幼虎22只(Matiukhina et al., 2016)。     

Motility and fertility of cryopreserved semen in Persian sturgeon,Acipenser persicus,stored for 30–60 min after thawing

We investigated the effect of storage times of frozen–thawed Persian sturgeon (Acipenser persicus) semen on the duration of sperm motility, percentage of motile sperm, and fertilization and hatching rates of fresh sperm and sperm stored for 0, 30, and 60 min at 4 °C post-thawing. Frozen thawed semen analyzed immediately after thawing had similar quality characteristics as fresh semen. For cryopreserved semen stored for 30 min after thawing the characteristics did not differ to fresh semen and cryopreserved semen. For cryopreserved semen stored for 60 min a significant decline in the parameters was observed. Fertilization and hatching rates were not affected by storage times of maximally 30 min of storage.     

吉林珲春自然保护区东北虎及其猎物资源调查

中国的野生东北虎(Panthera tigris altaica)数量已降到了极低的状态,及时开展有关东北虎及其猎物资源野外调查,对了解东北虎生存现状和制定保护策略都具有重大意义.吉林珲春东北虎国家级自然保护区是我国现存东北虎活动最频繁的地区之一,为了解该保护区的东北虎及其猎物资源状况,2009～2010年冬季,采用样...     

Genome-wide analysis of the Chinese sturgeon sox gene family: identification,characterisation and expression profiles of different tissues

The sox family is assumed to be responsible for a number of developmental systems. Genome sequencing technology makes it possible to scan sox genes and conduct characteristic analyses of different species. In fish, full characterisation of sox genes at the genome-wide level has been reported for pufferfish Takifugu rubripes, medaka Oryzias latipes, tilapia Oreochromis niloticus and channel catfish Ictalurus punctatus. However, no systematic investigation of the sox family in sturgeons (Acipenseridae) has been reported to date. This study conducted genome-wide identification of the sox genes in the Chinese sturgeon Acipenser sinensis and profiled their tissue distribution between male and female individuals. In total, 19 sox genes were identified, including soxb1, b2, c, d, e, f and h, in the Chinese sturgeon. Genomic structure analysis indicated relatively conserved exon–intron structures in each sox group and phylogenetic analysis supported the previous classification of the sox family. Most of the sox genes showed a tissue-specific expression pattern, indicating the possible involvement of Chinese sturgeon sox genes at different developmental processes such as cardiac and gonadal development. This study provides a comprehensive resource of Chinese sturgeon sox genes and enables a better understanding of the evolution and function of the sox family.     

Improved genetic identification of acipenseriform embryos with application to the endangered pallid sturgeon Scaphirhynchus albus

We produced pallid sturgeon Scaphirhynchus albus embryos at five pre-hatch developmental stages and isolated and quantified genomic DNA from four of the stages using four commercial DNA isolation kits. Genomic DNA prepared using the kit that produced the largest yields and concentrations were used for microsatellite DNA analyses of 10–20 embryos at each of the five developmental stages. We attempted to genotype the hatchery-produced embryos at 19 microsatellite loci and confirmed reliable genotyping by comparing the microsatellite genotypes to those of known parents. Embryos at stages 5 and 8 did not produce reliable genotyping while those at stages 14, 24 and 33 did. We used the same DNA isolation method on 262 wild-caught acipenseriform embryos collected from the lower Yellowstone River. A total of 200 of the wild embryos were successfully identified to stages 8 to 34 and the rest could not be staged. Using a combination of single nucleotide polymorphism and microsatellite markers, 249 of the wild-caught embryos were genetically identified as paddlefish Polyodon spathula, five were identified as shovelnose sturgeon Scaphirhynchus platorynchus and eight failed to amplify. None were identified as pallid sturgeon. This study demonstrates that early-stage wild-spawned acipenseriform embryos can be genetically identified less than 24 h post-spawn. This methodology will be useful for recovery efforts for endangered pallid sturgeon and can be applied to other acipenseriform species.     

First observations of intersex development in paddlefish Polyodon spathula

This study reports the first cases of intersex (abnormal development of both male and female reproductive tissues in a gonad) paddlefish Polyodon spathula, an Acipenseriform species of large rivers in the central U.S. and in aquaculture worldwide. Despite a large, multi-decadal data set in Oklahoma, Montana, and North Dakota, intersex development was not observed until 2019, when two individuals were harvested from the Grand Lake/Neosho River stock in Oklahoma. This suggests that intersex development in mid-water, zooplanktivorous paddlefish is rarer than in bottom-dwelling sturgeons for which intersex development is regularly observed. Although contaminants are implicated in causing intersex development in other Acipenseriformes, more investigation is needed.     

Genetic monitoring of progeny derived from natural spawning of Acipenser ruthenus Linnaeus, 1758 and Acipenser stellatus Pallas, 1771 as well as their hybrids in the Lower Volga river during the period 2017 to 2019

The state of natural spawning of sturgeons in the Lower Volga River was investigated through genetic monitoring of juveniles (larvae, fingerlings, subadults) captured at seven traditionally used monitoring locations. Sampling was performed during the period 2017–2019. In total, 460 individuals were caught and genotyped using a set of six microsatellite loci (Afug41, Afug51, Afug135, An20, AoxD161, AoxD165) and mtDNA control region sequencing. The observed species-specific microsatellite alleles revealed the presence of juvenile sturgeons originating from natural spawning also included some hybrids between Acipenser stellatus and A. ruthenus. Thus, the majority of sterlet breeding takes place in natural spawning grounds but also sterlet hybridizes with a small number of stellate sturgeons. Juveniles of other sturgeon species were not identified, and it is concluded that natural spawning activities of Russian sturgeon, beluga and ship sturgeon were insignificant or even absent in the Lower Volga during the observation period.     

Characterization of Pallid Sturgeon (Scaphirhynchus albus) Spawning Habitat in the Lower Missouri River

Acipenseriformes (sturgeons and paddlefish) globally have declined throughout their range due to river fragmentation, habitat loss, overfishing, and degradation of water quality. In North America, pallid sturgeon (Scaphirhynchus albus) populations have experienced poor to no recruitment, or substantial levels of hybridization with the closely related shovelnose sturgeon (S. platorynchus). The Lower Missouri River is the only portion of the species’ range where successful reproduction and recruitment of genetically pure pallid sturgeon have been documented. This paper documents spawning habitat and behavior on the Lower Missouri River, which comprises over 1,300 km of unfragmented river habitat. The objective of this study was to determine spawning locations and describe habitat characteristics and environmental conditions (depth, water velocity, substrate, discharge, temperature, and turbidity) on the Lower Missouri River. We measured habitat characteristics for spawning events of ten telemetry-tagged female pallid sturgeon from 2008–2013 that occurred in discrete reaches distributed over hundreds of kilometers. These results show pallid sturgeon select deep and fast areas in or near the navigation channel along outside revetted banks for spawning. These habitats are deeper and faster than nearby river habitats within the surrounding river reach. Spawning patches have a mean depth of 6.6 m and a mean depth-averaged water-column velocity of 1.4 m per second. Substrates in spawning patches consist of coarse bank revetment, gravel, sand, and bedrock. Results indicate habitat used by pallid sturgeon for spawning is more common and widespread in the present-day channelized Lower Missouri River relative to the sparse and disperse coarse substrates available prior to channelization. Understanding the spawning habitats currently utilized on the Lower Missouri River and if they are functioning properly is important for improving habitat remediation measures aimed at increasing reproductive success. Recovery efforts for pallid sturgeon on the Missouri River, if successful, can provide guidance to sturgeon recovery on other river systems; particularly large, regulated, and channelized rivers.     

Twenty-one novel tri- and tetranucleotide microsatellite loci for the Amur tiger (Panthera tigris altaica)

Amur tiger is the largest subspecies of tiger in the world and his conservation has also received much attention. In this study, we isolated and characterized twenty-one tri- and tetranucleotide microsatellite markers from this species. The number of alleles for each locus ranged from two to nine in a group of 60 individuals and the observed and expected heterozygosities were 0.333–0.917 and 0.302–0.822, respectively. The overall discrimination power and exclusion probabilities in parentage and paternity testing for these markers were 1.00, 0.9947 and 0.9999, respectively, indicating high-resolution power of microsatellite markers.