Prolonged low-salt immersion effectively controls Flavobacterium columnare infection in Murray cod Maccullochella peelii peelii.

A disease outbreak occurred in Murray cod Maccullochella peelii peelii in a recirculating aquaculture farm in Tianjin city, China, in 2019. Strain MRX-2019 was isolated and considered to be the etiological pathogen; it was identified as Flavobacterium columnare based on a 16S rDNA gene sequence analysis and physiological and biochemical tests. The effect of salinity on the growth of MRX-2019 was investigated in vitro. Salinity >4‰ (i.e. 6‰) inhibited MRX-2019 growth, whereas 8 and 10‰ salinity killed it. The effect of 4‰ salinity on F. columnare was not significant (p > 0.05). When MRX-2019-infected Murray cod were treated with 4, 6, or 8‰ salinity, the mortality rate was reduced by 8.9, 67.76, or 75.56%, respectively, compared with that of the control. However, the mortality rate increased by 7.77% at 10‰ salinity. In this study, we found that maintaining the fish in freshwater with 6-8‰ salinity effectively reduced the mortality of these fish when infected with F. columnare. The findings provide an environmentally friendly control strategy for columnaris disease in Murray cod.

Evaluation of Several Satellite-Based Soil Moisture Products in the Continental US.

Satellite-based soil moisture products are suitable for large-scale regional monitoring due to the accessibility. Five soil moisture products including SMAP, ESA CCI, and AMSR2 (ascending, descending, and average) were selected in the continental United States (US) from 2016 to 2021. To evaluate the performance of the products and assess their applicability, ISMN (International Soil Moisture Network) data were used as the in situ measurement. PBIAS (Percentage of BIAS), R (Pearson correlation coefficient), RMSE (Root Mean Square Error), ubRMSE (unbiased RMSE), MAE (Mean Absolute Error), and MBE (Mean Bias Error) were selected for evaluation. The performance of five products over six observation networks and various land cover types was compared, and the differences were analyzed at monthly, seasonal, and annual scales. The results show that SMAP had the smallest deviation with the ISMN data because PBIAS was around -0.13, and MBE was around -0.02 m3/m3. ESA CCI performed the best in almost all aspects; its R reached around 0.7, and RMSE was only around 0.07 m3/m3 at the three time scales. The performance of the AMSR2 products varied greatly across the time scales, and increasing errors and deviations showed from 2016 to 2020. The PBO_H2O and USCRN networks could reflect soil moisture characteristics in the continental US, while iRON performed poorly. The evaluation of the networks was closely related to spatial distributions. All products performed better over grasslands and shrublands with R, which was greater than 0.52, and ubRMSE was around 0.1 m3/m3, while products performed worse over forests, where PBIAS was less than -0.62, and RMSE was greater than 0.2 m3/m3, except for ESA CCI. From the boxplot, SMAP was close to the ISMN data with differences less than 0.004 m3/m3 between the median and lower quartiles.

First report of a disease caused by Bacillus cereus in cultured loach Paramisgurnus dabryanus.

Bacillus cereus is commonly considered a bacterium pathogenic to mammals, but several studies have suggested that it also induces diseases in fish. In 2017 and 2018, 2 strains of B. cereus, NQ-2017-17 and NQ-2018-8, were isolated from diseased large-scale loach Paramisgurnus dabryanus in Tianjin, China, and were considered to be the pathogens responsible for the disease. These stains were identified as B. cereus based on the results of 16S rDNA gene sequence analysis, Vitek biochemical tests, physiological and biochemical tests, and B. cereus group species-specific PCR. Strains NQ-2017-7 and NQ-2018-8 were found to contain virulence genes (e.g. hblA, hblC, hblD, entFM, and bceT) causing pathological damage to the spleen, kidneys, liver, and gills of loach. The median lethal dose (LD50) of NQ-2017-7 and NQ-2018-8 for loach were 1.0 ×106.64 and 1.0 ×106.49 CFU ml-1, respectively. To our knowledge, this is the first report of loach disease caused by a member of the genus Bacillus.

How does virtual water influence the water stress pattern in Africa? A research perspective from the perspectives of production and trade.

Northern Africa has become the first region in the world to exhaust its water resources, with a 40 % decrease in per capita water availability south of the Sahara over the past decade. While adjusting production structures and consumption can regulate the supply-demand dynamics of water resources, the extent of the impact of virtual water-induced pressure on both the regional and national levels in Africa remains largely understudied. Applying the standard Penman formula, this research calculates the water footprint of eight cereal crops in 54 African countries from 1990 to 2021. By integrating corresponding data on cereal trade, the study analyzes changes in virtual water stress. The findings indicate a decline in the per-unit production and consumption water footprints for African cereals. However, the continuous expansion of cultivation areas contributes to a rising water stress. In comparison to 1990, the water stress for soybeans, sorghum, rice, maize, and cassava increased by 149.72 %, 146.88 %, 133.89 %, 123.30 %, and 90.8 %, respectively, in 2021. Only barley showed a reduction in water stress by 23.22 %. The study underscores the growing interconnectedness of virtual water trade (VWT) among African nations from 1990 to 2021, leading to a more balanced trade distribution. VWT has reduced water stress by 7.65 %, 2.08 %, and 1.8 % in Western, Central, and Northern Africa, respectively, while increasing pressure in Southern and Eastern Africa by 10.51 % and 1.01 %. The flow of virtual water in Africa is most influenced by spatial proximity, primarily occurring between adjacent countries or regions. Forecasts for water stress under the five scenarios of SSPs-RCP8.5 have been conducted, revealing a continuous increase in water stress across Africa. Furthermore, analysis of the SSP2-RCP8.5 scenario indicates that by 2030 and 2040, African cereal crops are projected to face virtual water resource stress increases of 7 % and 18.76 %, respectively, compared to 2020 levels. During the same period, Sierra Leone is anticipated to experience a growth rate in virtual water stress of approximately 1903.38 %. Consequently, altering crop cultivation structures and enhancing VWT are poised to alleviate water resource pressure, promoting the scientific management of agricultural water resources in Africa.

Response of mucosal and systemic sIgM-positive cells in turbot (Scophthalmus maximus L.) immunization with Edwardsiella tarda.

Indirect fluorescence analyze technology (IFAT) and fluorescence-activated cell sorter (FACS) analysis were used to detect surface IgM positive cells (sIgM+ cells) in lymphoid tissues of unvaccinated turbots and vaccinated ones with inactivated Edwardsiella tarda. The results were as follows: (1) The percentage of sIgM+ cells respectively was 0+/-0.00% of skin, 1.58+/-0.40% of gills, 17.05+/-0.39% of peripheral blood (PBL), 21.06+/-1.79% of kidney in unvaccinated healthy turbots (average length: 7.12+/-0.5 cm; average height: 3.8+/-0.2 cm). (2) After direct immersion (d.i.), the response of sIgM+ cells was produced at first in the gills and thereafter in the kidney and PBL, and a significant increase of the number of sIgM+ cells was found in gills. (3) After immunization via intraperitoneal injection (i.p.), the response of sIgM+ cells was produced simultaneously in the gills, kidney and PBL after i.p., and a significant increase of the number of sIgM+ cells was found in PBL and kidney instead of in gills. These results strongly supported the different immunological role of gills, PBL and kidney upon the different administration routes, and the presence of two compartmental models for immune response in turbot.

The complete mitochondrial genome of Hypomesus olidus (Osmeriformes: Osmeridae).

Pond smelt Hypomesus olidus is a small-sized economic species of freshwater fish with delicious meat and high output. In this study, the complete mitochondrial genome of H. olidus sequenced to be 16,786 bp in length, including 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNAs and a control region. The overall base composition of H. olidus is 24.3% for A, 27.3% for T, 29.2% for C and 19.2% for G, with a slight A + T bias. The mitogenome sequence data may provide useful information to the population genetics analysis of H. olidus and the elucidation of evolutionary mechanisms in Hypomesus fish.

The complete mitochondrial genome of Hemigrammus bleberi.

The complete mitochondrial genome of Hemigrammus bleberi was obtained by the traditional polymerase chain reaction (PCR)-based sequencing approach. The mitogenome of H. bleberi was determined as 17 021bp in length, including 13 protein-coding genes, 22 transfer RNA genes and 2 ribosomal RNA genes. Phylogenetic tree was constructed based on the complete mitogenomes of the species and closely related 21 teleost species to assess their phylogenetic relationship and evolution.

The complete mitochondrial genome of Andinoacara rivulatus.

The traditional polymerase chain reaction method was employed to obtain the complete mitochondrial genome of Andinoacara rivulatus from Lizigu farm, Tianjin city, China. The mitogenome was determined to be 16,585 bp in length. It contains 13 protein-coding genes, 2 rRNAs and 22 tRNAs. The sequence structure of non-coding control region was also analyzed. This is the first report on the complete mitogenome sequence of A. rivulatus.