Guanine-cytosine contents of the host and symbiont cDNA in a symbiotic coral

ABSTRACT:   Hermatypic (reef-building) corals harbor dinoflagellate endo-symbionts Symbiodinium spp. In studying gene expression in such symbiotic corals, problems arise regarding how to distinguish the coral and symbiont mRNA, and how to estimate their fractions in the mRNA population of the holobiont (symbiotic complex of the coral and Symbiodinium cells). In this study, these issues were addressed using juveniles of hermatypic coral Acropora tenuis in symbiosis with Symbiodinium cells of strain PL-TS-1. First, the guanine-cytosine (GC) contents were determined in expressed sequence tags (EST) from PL-TS-1 cells cultured in vitro and symbiont-free larvae of A. tenuis , and their average GC contents were found to be significantly different. The average GC content of the EST from the holobiont was much closer to that of A. tenuis larvae, suggesting that the majority (>90%) of mRNA isolated from the holobiont originated in the host. In protein-coding sequences, little overlap was observed between the GC-content distributions of PL-TS-1 cells and A. tenuis larvae. All of the coding sequences ( n  = 59) found in the A. tenuis EST had GC contents below 0.5, whereas the GC content exceeded 0.5 in the majority (43/44) of coding sequences from the nuclear genome of PL-TS-1 cells.     

Bioaccumulation of cadmium and its biochemical effect on selected tissues of the catfish (<Emphasis Type="Italic">Clarias gariepinus</Emphasis>)

The present study examines the pattern of accumulation of cadmium (Cd) and its biochemical effects on selected tissues of a variety of African catfish (Clarias gariepinus), after exposure to various doses of Cd. The results obtained indicate that at the end of 21 days of exposure, the total tissue organ cadmium concentration followed the pattern kidney > gill > liver > muscle for each of the exposure concentrations. The levels of Cd in these organs were higher than those in ambient water. Moreover, while the rate of uptake of Cd increased with time in the kidney, liver and muscle, it decreased in the gill. Superoxide dismutase (SOD) was significantly elevated only in the kidney of catfish treated with 0.2 and 0.4 ppm of Cd for 7 days compared with the control. Conversely, gill SOD was significantly decreased in the same concentrations of Cd-treated catfish relative to the control. Statistically similar levels of SOD were observed in the liver, brain and muscle with all the treatments after the same duration of treatment. In the fish exposed for 21 days, SOD activity was significantly decreased in the kidney with a corresponding increase in lipid peroxidation (LPO), but it manifested only with the 0.2- and 0.4-ppm Cd treatment relative to the control. In the liver, however, Cd exposure significantly increased SOD in the 0.2- and 0.4-ppm treatments of the same duration. In conclusion, the present study indicates that the accumulation of Cd and its effect on SOD and LPO in C. gariepinus is dependent on concentration, tissue and time     

Genetic differentiation and diversity of phenotypic characters in Chinese wild soybean (<Emphasis Type="Italic">Glycine soja</Emphasis> Sieb. et Zucc.) revealed by nuclear SSR markers and the implication for intraspecies phylogenic relationship of characters

Genetic diversity is reduced from wild soybean to cultivars and from landraces to modern varieties. However, intraspecies genetic diversity loss between characters or phenotypes also existed in wild soybean. We revealed the phylogenic relationship of character types in Chinese wild soybean using 42 SSR markers. We conjectured that white flower, no-seed bloom, grey pubescence, and four seed coat colours were evolutionarily acquired phenotypes. There were a small decrease (∆H = 0.1–6.46%) of gene diversity and a moderate reduction (∆Na = 10.81–53.54%) of number of alleles but a violent loss (80.74–98.59%) of unique alleles in the acquired phenotypes. Our results seemed to suggest that ovoid and elliptic leaves were differentiated at the earliest and subsequently lanceolate leaf appeared before the domestication of soybeans within wild soybean, and that G. gracilis type was another earliest type, maybe emerged since the appearance of soybeans or it was concomitant with the domestication of soybean.     

Building resilience to climate change in rain-fed agricultural enterprises: An integrated property planning tool

In response to a drying climate, an integrated property planning tool was developed over three years to help landowners make better use of available rainfall. A sequence was identified which indicated how parts of each property are affected by soil moisture limitations. The sequence was combined with soil properties to indicate targeted strategies for each location aimed to improve soil moisture availability, biomass utilisation, and long-term viability of the farm or ranching enterprise. As a result of training of land owners and operators in use of this tool, 97% of participants indicated that they have begun or intend to make changes in land management; 78% are intending to make three or more substantial changes; and 91% felt better prepared for the impacts of climate change. The key to the success of this technique is that it identifies critical sustainable production drivers in a simple plan format and offers tailored management options which can address more variable climate conditions. The integrated planning tool has application as a driver of climate change adaptation in agricultural regions where farm units contain substantial landscape variation and seasonal rainfall is frequently limiting to production.     

Changes of gene expression in early generations of the synthetic allotetraploid <Emphasis Type="Italic">Cucumis</Emphasis> × <Emphasis Type="Italic">hytivus</Emphasis> Chen et Kirkbride

Changes of gene expression played an important role in the evolution of plant allopolyploids. Frequency, time and type of the changes of gene expression between the first two self-pollinated generations (S₁ and S₂) of a synthesized allotetraploid Cucumis × hytivus Chen et Kirkbride and in its diploid parents was analyzed with cDNA-AFLP and reverse-Northern blot technique. Sequences similarity of genes involved in changed expression were also analyzed with BLAST package. The results from cDNA-AFLP analysis showed that 36 (3.37%) genes showed silencing (27) or activation (9) in allotetraploids. These changes initiated in S₁ or S₂ generation. The silenced/activated genes included rRNA and protein-coding genes. Further reverse-Northern blot analysis validated the results obtained. Thus four types of changes of gene expression were observed, including silencing of genes from both parents, maternal parent, paternal parent, and genes novel expression. The results indicate rapid changes in gene expression in early generations of C. × hytivus, which contributed to the evolution of this synthetic allotetraploid.     

A dual-spectral camera system for paddy rice seedling row detection

A new method is presented for detecting rows of rice seedlings to facilitate the navigation of rice transplanters. Generally, an independent NIR or RGB camera is used as a vision sensor for agricultural vehicles; however, strong reflections on the water surface make row detection more difficult in flooded paddy fields compared to dry fields. To solve this problem, we developed a dual-spectral camera system that consists of a pair of low-cost monochrome cameras with optical filters. Different wavelength images of the same location can be taken simultaneously in real-time. An experiment conducted under cloudy conditions showed that this system could reduce water surface noise and clearly detect seedling rows.     

Field variability and vulnerability index to identify regional precision agriculture opportunity

Innovations in precision agriculture (PA) have created opportunities to achieve a greater understanding of within-field variability. However, PA adoption has been hindered by uncertainty about field-specific performance and return on investment. Uncertainty could be better addressed by using innovative analyses that provide insights into variability among fields and across a region. The objectives of this research were to: (1) generate a within-field soil clay-content variability index (VI_c), (2) create a regional-scale growing-season precipitation variability index (VI_p), and (3) integrate the soil and weather indices with the USDA NRCS soil erosion vulnerability index (SVI) to produce a final index that incorporated both variability and vulnerability (VVI). The interpretation of the outcomes represented by each objective supports unique decisions that land managers may consider for reducing uncertainty about implementing PA. All indices were derived using publically available information for Missouri, USA. The VI_c was the ratio between the maximum and minimum clay content within fields. The VI_p was calculated as the standard deviation of the total growing-season precipitation from 2006 to 2015. Significant clustering of VI_c and VI_p were observed along the Missouri River corridor, northeast and northwest Missouri. Fields with high VVI were mostly in the claypan soil region of northeast Missouri, and along a portion of the Missouri River dominated by loess soils on steep slopes. Southeast Missouri displayed the greatest diversity in soil and weather variability, but had low vulnerability. This research could be used as a decision-support tool to aid producers and PA service and product providers in determining where PA opportunities exist.     

Production of trout offspring from triploid salmon parents

Many salmonids have become at risk of extinction. For teleosts whose eggs cannot be cryopreserved, developing techniques other than egg cryopreservation to save genetic resources is imperative. In this study, spermatogonia from rainbow trout were intraperitoneally transplanted into newly hatched sterile triploid masu salmon. Transplanted trout spermatogonia underwent spermatogenesis and oogenesis in male and female recipients, respectively. At 2 years after transplantation, triploid salmon recipients only produced trout sperm and eggs. With use of these salmon as parents, we successfully produced only donor-derived trout offspring. Thus, by transplanting cryopreserved spermatogonia into sterile xenogeneic recipients, we can generate individuals of a threatened species.