Rice Fish Research Articles

Ecological mechanism and diversity in rice based integrated farming system

The dynamic and transitional characteristics of rice field ecosystems provide an excellent environment for integration with compatible components such as fish and duck, which enhances the overall productivity through the effective nutrient recycling. The ecological mechanisms underlying the rice-fish-duck system sustainability have not been studied in detail especially on soil and water chemistry, dynamics of plankton, microbe and benthic populations and their community compositions. Therefore, the present study was undertaken to understand the ecological significance and diversities of organisms in the processes of maintenance of soil health, nutrient recycling and sustainable productivity in different rice-based integrated farming systems. In the integrated system such as rice-fish (RF), rice-duck (RD), and rice-fish-duck (RFD); the physico-chemical parameters of water (dissolved oxygen, nitrate, ammonia, total alkalinity, dissolved organic matter, and total suspended solid) and soil nutrient levels were significantly higher compared to conventional system due to the continuous addition of fecal matters, scooping and churning of soil by fish and ducks in the paddy field ecology. The aquatic biological diversity including planktons (phyto- and zooplankton), soil benthic fauna and microbial populations were dynamic in integrated rice-based system, provides an indication of enhanced soil fertility and production sustainability. The observed decreasing trends of plankton and soil benthic populations in integrated systems (RF, RD and RFD) indicated that fish and ducks fed these materials in rice ecology. Higher productivity and profitability in term of rice equivalent yields (REY) and the ratio of output value and cost of cultivation (OV/CC) were achieved in integrated farming system as compared to conventional rice farming (CRF). Thus, the present study reveals that adoption of rice-fish-duck integrated farming system enhances total farm production and income. Besides, the evaluation of different indicator indices viz., water quality index (WQI) and soil quality index (SQI) have shown a good prediction about ecological aspects of agro-ecosystems and will be helpful in farm management decisions making processes for improving farm productivity, profitability, and overcome any potential limiting factors in the rice-fish-duck integrated farming system. Finally, the present study concluded that rice-fish-duck integration utilizes maximum ecological niches and converted into potential production processes, which enhances farm production, farmer income and improved the soil health through the effective nutrient recycling in the rice ecologies.

Bioaccumulation and oxidative stress caused by pesticides in Cyprinus carpio reared in a rice-fish system

Nowadays, many irrigated rice producers have adopted the rice-fish farming systems, in which fish are reared in the same environment as rice is grown. These animals can biologically control many pests that disturb the crop, as well as increase the income of producers when they are reared in the same area as rice. However, a large variety of pesticides is often used for pest control in conventional irrigated rice crops, and fish are exposed to different pesticide concentrations and active ingredients. Thus, the aim of the current study is to assess the potential risks of these pesticides to freshwater fish (Cyprinus carpio) cultured in integrated rice–fish farming systems. We assessed five pesticides widely used in rice culture. This is the first report on the bioaccumulation of the insecticides lambda-cyhalothrin + thiamethoxam and clorantraniliprole and of the fungicide tebuconazole + trifloxystrobin associated with oxidative stress and with enzymatic and non-enzymatic parameters in edible fish samples reared in integrated in rice–fish farming systems. After 100 days of exposure, lambda-cyhalothrin and tebuconazole bioaccumulated in carp muscles. Acethylcholinesterase activity in the brain was lower in the experimental group than in the control group. Overall, the biochemical analyses showed increased responses in the experimental groups in comparison to the controls. Lipid peroxidation levels increased in the liver, gills and muscles. Protein oxidation increased in the liver and muscles. Catalase activity increased in the liver, and glutathione S-transferase increased in the liver, gills and muscles. Results demonstrate that these pesticides have severe adverse consequences in fish and indicate their potential risk to human health due to their bioaccumulation in farmed fish.

Preservation of the genetic diversity of a local common carp in the agricultural heritage rice–fish system

We examined how traditional farmers preserve the genetic diversity of a local common carp (Cyprinus carpio), which is locally referred to as "paddy field carp" (PF-carp), in a "globally important agricultural heritage system" (GIAHS), i.e., the 1,200-y-old rice-fish coculture system in Zhejiang Province, China. Our molecular and morphological analysis showed that the PF-carp has changed into a distinct local population with higher genetic diversity and diverse color types. Within this GIAHS region, PF-carps exist as a continuous metapopulation, although three genetic groups could be identified by microsatellite markers. Thousands of small farmer households interdependently obtained fry and parental carps for their own rice-fish production, resulting in a high gene flow and large numbers of parent carps distributing in a mosaic pattern in the region. Landscape genetic analysis indicated that farmers' connectivity was one of the major factors that shaped this genetic pattern. Population viability analysis further revealed that the numbers of these interconnected small farmer households and their connection intensity affect the carps' inherent genetic diversity. The practice of mixed culturing of carps with diverse color types helped to preserve a wide range of genetic resources in the paddy field. This widespread traditional practice increases fish yield and resource use, which, in return, encourages famers to continue their practice of selecting and conserving diverse color types of PF-carp. Our results suggested that traditional farmers secure the genetic diversity of PF-carp and its viability over generations in this region through interdependently incubating and mixed-culturing practices within the rice-fish system.

English

This study was undertaken in the main Côte d’Ivoire fish farming production regions. Fish farming were surveyed on the basis of socio-economic characteristics of fish farmers, farming practices and production depending to the systems. Results show that majority of fish farmers used semi intensive (51.8%) and extensive (42.9%) systems. Intensive system represented only 1.3% and rice-fish system 4.0% of fish farms. Tilapia, Heterotis and Catfish were the most species reared with frequencies depending to the system. In intensive system, rearing structures were tanks and floating cages and farms owner were native (50%) economic operator (75%) or salaried (25%). In contrast, in semi intensive systems, the popular rearing structures were earthen ponds (68.6%), and farms belong to native (61.5%) farmers (46.3%). Extensive and rice fish farming used earthen ponds associated to dams (52.7-66.7%) and 45.7-50% of proprietary were allochthonous famers (77.5-91.7%). Imported (50%) and national commercial feeds (50%) were used in intensive system. In semi intensive system, national commercial feeds (55.13%), agro-industrial byproducts (46.79%) and feeds produced by fish farmers (33.97%) were largely used while agro-industrial byproducts and/or non-conventional feeds were used in extensive and rice-fish system to feed fish. The average farm production of semi intensive and extensive systems most practiced varied between 395.25 and 2937.12 kg/year. The results suggest that optimization of the Ivorian fish farming production need the adoption of appropriate production practices. They also emphasize the need to promote the intensive and semi intensive systems to increasing marketable fish production.   Key words: Fish farming, System, socio-economic, farming practices, production.

Chinese Consumer Quality Perception and Preference of Traditional Sustainable Rice Produced by the Integrated Rice–Fish System

Historically, humans have created many sustainable practices, and among the most famous and successful sustainable practice is the rice–fish system in China. While previous studies have investigated eco-labeling food from various angles, consumer perception and preference of food produced from traditional sustainable practices (traditional sustainable food) remain unexplored. Taking the historical rice–fish system as an example, we examined consumers’ perception and willingness to pay (WTP) for rice produced by a rice–fish system, by using data from 1422 consumers from China. Our paper shows that most Chinese consumers do understand the meaning of the rice–fish system and perceive the traditional sustainable system as environmentally friendly and producing high-quality food. The premium that consumers are willing to pay for rice from a rice–fish system is about 41%. Consumers who perceive the linkage between sustainable production and food quality and safety have a significantly higher WTP for traditional sustainable rice (p-value = 0.000). Interestingly, the perception of environment risk does not directly cause more traditional sustainable food consumption, but those who self-proclaimed as environmentalists are willing to pay a premium for traditional sustainable rice. Females, people with high family income, and people with children are more willing to pay for traditional sustainable rice. Understanding consumer perception and preference of traditional sustainable food provides critical information for Chinese policymakers to develop a cheap and efficient way to keep traditional sustainable practices and promote sustainable food consumption.

Invasiveness screening of non‐native fishes for the middle reach of the Yarlung Zangbo River, Tibetan Plateau, China

AbstractThe aim of this study was to identify potentially invasive non‐native freshwater fishes in the middle reach of the Yarlung Zangbo River, Tibetan Plateau (China), using the Aquatic Species Invasiveness Screening Kit (AS‐ISK), as decision‐support tool. Based on independent evaluations of 24 non‐native freshwater fishes, receiver operating curve analysis identified a threshold score of ≥29 for distinguishing species likely to pose a high risk of becoming invasive from species likely to pose low‐to‐medium risk (<29) in the risk assessment area. Nine species were categorized as “high risk”: goldfish Carassius auratus, topmouth gudgeon Pseudorasbora parva, brook trout Salvelinus fontinalis, Oriental weatherfish (a.k.a. dojo gudgeon) Misgurnus anguillicaudatus, Siberian taimen Hucho taimen, common carp Cyprinus carpio, peled Coregonus peled, western mosquitofish Gambusia affinis, and Chinese rice fish Oryzias sinensis. The three lowest scoring species were Arctic cisco Coregonus autumnalis, Wuchang bream Megalobrama amblycephala, and Chinese ice fish Neosalanx taihuensis, which are unlikely to be invasive because they are unable to complete their life cycle in the risk assessment area. Climate change assessments scores increased or remained the same for warm‐water species and decreased for coldwater species. This study was the first application of AS‐ISK in western China, and the results suggest that AS‐ISK is a useful and valid tool for identifying potentially invasive risk aquatic species in China.

Ontogenesis of Tet Family of Methylcytosine Dioxygenase Enzyme Genes During Japanese Rice Fish (Oryzias Latipes) Embryogenesis: Effects Of Ethanol and 5-azacytidine

Ontogenesis of Tet Family of Methylcytosine Dioxygenase Enzyme Genes During Japanese Rice Fish (Oryzias Latipes) Embryogenesis: Effects Of Ethanol and 5-azacytidine

Effects of supplementary feeds with different protein levels on growth and economic performances of Nile tilapia (Oreochromis niloticus) cultured in a rain-fed rice–fish ecosystem

ABSTRACTThis study investigated the effects of supplementary feeds with different crude protein (CP) levels on the growth and economic performances of sex-reversed Nile tilapia (Oreochromis niloticus) reared in a rain-fed rice–fish ecosystem for a period of 120 days. There were four treatments—namely, traditional feed (21% CP), formulated feed (26% CP), commercial feed (30% CP), and control (no feed was used)—with three replicates per treatment. Fish (30.04 g) were stocked in ditches at a rate of 0.5 fish m−2 considering the total area and fed one of the tested feeds twice daily at the rate of 2%–5% of body weight. Water-quality parameters of the ditches were monitored fortnightly, and these parameters were found suitable for fish farming. Organic matter, total nitrogen, and available phosphorous in soil were increased significantly (P < 0.05) in the feed treatments after fish cultivation. Highly significant weight gain and SGR were observed with fish fed the commercial feed as compared with other treatments. The highest benefit-cost ratio (2.15) was found in the control, followed by formulated feed (1.90), but in the case of numerical net return, it was the opposite. However, commercial feed showed the lowest benefit-cost ratio (1.67) due to higher feed cost than other supplementary feeds. Therefore, this study suggests that fish fed with a formulated feed (26% CP) produced significantly higher net economic return in the rice–fish farming system.

Conspecific injury raises an alarm in medaka.

In the late 1930s, Karl von Frisch reported that semiochemicals released upon injury, act as alarm substances (Schreckstoff) in fish. In Ostariophysi species, club cells in the epidermis are believed to contain cues related to alarm substance; however, the function of club cells, primarily as reservoirs of alarm substance has been debated. Here, I describe an alarm response in the Japanese rice fish Oryzias latipes (medaka), a member of the order Beloniformes. The response to alarm substance (Schreckreaction) in medaka is characterized by bouts of immobility and an increase in cortisol levels within minutes of exposure to conspecific skin extract. Histological analysis, however, suggests that club cells are either rare or absent in the medaka epidermis. In addition to describing an uncharacterized behavior in a vertebrate popular for genetic and developmental studies, these results support the hypothesis that the primary function of epidermal club cells may be unrelated to a role as alarm substance cells. The existence of similar behavioral responses in two evolutionarily distant but well established laboratory models, the zebrafish and the medaka, offers the possibility of comparative analyses of neural circuits encoding innate fear.

Nồng độ quinalphos trong nước, cá chép (Cyprinus carpio) và cá mè vinh (Barbonymus gonionotus) trong mô hình lúa cá kết hợp

Quinalphos, Kinalux 25EC brand name, is popularly used in agriculture of the Mekong Delta. To figure out the residue concentration and bio-concentration ability of quinalphos in rice fish system in Co Do District, Can Tho City, Kinalux 25EC was applied twice in rice fish field with the producer recommended dose which was 170 mL/1000m2. Samples were collected at the day 1, 3, 7 and 14 after application, then, samples were continuously collected every 14 days to the end of experiment. Water samples were also collected after 30 minutes of applications. Residues of quinalphos were analysed by gas chromatography – electron capture detector system (GC-ECD). The results showed that quinalphos residues in fish tissue were much higher than in water. The half-life varied between one and two days fish tissue and around one day for water.

Integrated Rizi-Pisciculture: An approach towards livelihood and nutritional security for the tribal community of East Siang district, Arunachal Pradesh

An approach was made to evaluate the feasibility and economic viability of rice fish culture (RFC) by conducting trials in 8 different villages viz. Ngorlung, Niglok, Balek, Mirem, Sikatode, Ayeng, Rayang and Seren of East Siang district, Arunachal Pradesh during Kharif seasons of 2011 to 2014. In the multilocational trials on rizi-pisciculture survival rate of advanced fry was recorded between 44.5% and 48.7% with an average weight of 83 g to 91 g at the harvest. During the study period average total cost of cultivation of RFC and sole cropping of rice was calculated to be ` 42, 700 and ` 26, 612 respectively. Average gross income and net income increased by ` 61, 937 and ` 44, 849 respectively by practicing RFC over the sole cropping of rice and it also raised the benefit-cost ratio of the system (2.61).

Expression and biological activity of two types of interferon genes in medaka (Oryzias latipes).

Type I interferon (IFN) is one of most important cytokines for antiviral responses in fish innate immunity, after the induction pathway following pattern recognition. In this study, 2 types of type I IFN mRNA from a medaka (Japanese rice fish; Oryzias latipes) were identified and classified (phylogenetic analysis) into subgroup-a and -d by (designated olIFNa and olIFNd, respectively). Both olIFNa and olIFNd (encoding 197 and 187 amino acid residues, respectively) contained 2 cysteines. Gene expression pattern of olIFNa, olIFNd and IFN-stimulated genes (ISGs) was assessed (quantitative real-time reverse transcriptase PCR, qRT-PCR) in various organs (i.e., whole kidney, liver and spleen) of medaka stimulated by polyI:C or infected with nervous necrosis virus (NNV). Expression of olIFNa, olIFNd and ISGs, especially the ISG15 gene, were significantly upregulated after NNV-infection. Furthermore, olIFNa, olIFNd and ISGs mRNAs were sufficiently induced in DIT cells (i.e., medaka hepatoma cell line) transfected with polyI:C or infected with NNV. In addition, invitro biological activities of recombinant olIFNa and olIFNd (rolIFNa and rolIFNd) produced by mammalian cell line HEK293T were also characterized. Expression of GIG1a and ISG15 genes in kidney cells of adult medaka were induced by rolIFNa or rolIFNd. The olIFNs-overexpressing DIT cells had reduced viral titers following NNV infection. Therefore, we inferred that 2 type I IFNs were involved in innate immunity (antiviral response) in medaka fish.

Modulation of DNA methylation machineries in Japanese rice fish (Oryzias latipes) embryogenesis by ethanol and 5-azacytidine

As a sequel of our investigations on the impact of epigenome in inducing fetal alcohol spectrum disorder (FASD) phenotypes in Japanese rice fish, we have investigated on several DNA methylation machinery genes including DNA methyl transferase 3ba (dnmt3ba) and methyl binding proteins (MBPs), namely, mbd1b, mbd3a, mbd3b, and mecp2 at the transcription level. Studies were made during normal development, from 0day post fertilization (dpf) to hatching, and also exposing the fertilized eggs to ethanol or a DNMT inhibitor, 5-azacytidine (5-azaC). We observed that during development, all these genes followed distinct expression patterns, generally high mRNA copies in early phases (0–1dpf) and significantly low mRNA copies prior to or after hatching. Ethanol (100–500mM, 0–2dpf) was unable to alter any of these mRNAs in 2dpf; additional four day (2–6dpf) maintenance of these embryos in ethanol-free environment, on 6dpf, was also unable to establish any significant difference in these mRNA levels in comparison with the corresponding controls. However, continuous exposure of fertilized eggs in 300mM ethanol, 0–6dpf, showed significantly high mRNA copies only in MBPs (mbd1b, mbd3a, mbd3b, mecp2). 5-azaC (2mM) on 2dpf was able to enhance only mbd3b mRNA. Removal of 5-azaC and maintenance of these embryos in clean medium, 2–6dpf, showed significantly enhanced mbd3b and mecp2 mRNAs compared to corresponding controls on 6dpf. Our studies showed that in Japanese rice fish embryogenesis both ethanol and 5-azaC have the potential to specifically modulate the developmental rhythm of DNA methylation machineries.

DNA methyltransferase expressions in Japanese rice fish (Oryzias latipes) embryogenesis is developmentally regulated and modulated by ethanol and 5-azacytidine

We aimed to investigate the impact of the epigenome in inducting fetal alcohol spectrum disorder (FASD) phenotypes in Japanese rice fish embryogenesis. One of the significant events in epigenome is DNA methylation which is catalyzed by DNA methyltransferase (DNMT) enzymes. We analyzed DNMT enzyme mRNA expressions in Japanese rice fish development starting from fertilized eggs to hatching and also in embryos exposed for first 48h of development either to ethanol (300mM) or to 5-azacytidine (5-azaC; 2mM), an inhibitor of DNMT enzyme activity. As observed in FASD phenotypes, 5-azaC exposure was able to induce microcephaly and craniofacial cartilage deformities in Japanese rice fish. Moreover, we have observed that expression of DNMTs (dnmt1, dnmt3aa, and dnmt3bb.1) are developmentally regulated; high mRNA copies were found in early stages (1–2day-post-fertilization, dpf), followed by gradual reduction until hatched. In ethanol-treated embryos, compared to controls, dnmt1 mRNA is in reduced level in 2dpf and in enhanced level in 6dpf embryos. While dnmt3aa and 3bb.1 remained unaltered. In contrast, embryos exposed to 5-azaC have an enhanced level of dnmt1 and dnmt3bb.1 mRNAs both in 2 and 6dpf embryos while dnmt3aa is enhanced only in 6dpf embryos. Moreover, endocannabinoid receptor 1a (cnr1a) mRNA which was found to be reduced by ethanol remained unaltered and cnr1b and cnr2 mRNAs, which were remained unaltered by ethanol, were increased significantly by 5-azaC in 6dpf embryos. This study indicates that the craniofacial defects observed in FASD phenotypes are the results of dysregulations in DNMT expressions.

Globally important agricultural heritage systems (giahs) of china: the challenge of complexity in research

The challenge of researching Globally Important Agricultural Heritage Systems (GIAHS) as complex systems forms the subject matter of this study. Complex adaptive systems are those that combine natural ecological processes with human interactions to produce a mutually supportive agro‐ecological system. In China, these highly varied systems have the added dimension of long historical time, in that they have evolved over many centuries and thus add a historical dimension to the natural and human dimensions of complexity. In preparing research on GIAHS, it is clear that seeing GIAHS sites as whole systems is an essential starting and ending point. Examining the adaptive capacity of a GIAHS with its multiple scales and complex interdependencies is a major challenge for researchers accustomed to specialized disciplinary thinking. A GIAHS represents a mature agro‐ecological system with human agency as a central component that has been honed over many centuries, and has already adapted to many perturbations and changes. The beauty of the GIAHS is in the integration of custom, knowledge, and practice, and it should be studied for its “wholeness” as well as for its resilience and capacity for “self organization.” The agro‐ecological approach opens the possibility of researching a system as a whole and of taking its complexity seriously. This study reviews the essential features of the GIAHS as a complex adaptive system where uncertainty is normal and surprise is welcome and, in a case study of Qingtian rice–fish culture system, focuses on new perturbations, namely loss of young people and the introduction of tourism.

Determination of Total Mercury in Sushi Samples Employing Direct Mercury Analyzer

In this study a simple, fast, and low-chemical- consuming method was evaluated for the determination of total mercury in sushi samples by thermal decomposition amalgamation atomic absorption spectrometry (TDA- AAS) using a direct mercury analyzer (DMA). A small portion of fresh sushi sample (60 mg) is combusted in nickel or quartz containers, and the released mercury is trapped in a gold amalgamator, being desorbed at high temperatures and measured in an atomic absorption cell. The method accuracy was evaluated using certified refer- ence materials (CRM) rice flour (NIST SRM 1568b), fish protein (NRC DORM-4), peach leaves (NIST SRM 1547), and oyster tissue (NIST SRM 1566b), and the method accuracy varied between 94 and 112 % for all the CRM. Analytical curves were prepared using 0.5 % nitric acid solutions (v/v )f or low (0.5 to 50μ gk g �1 )a nd high concentrations (100 to 1000 μ gk g �1 )a nd the corre- lation coefficients were above 0.999. The detection and quantification limits were 0.4 and 1.4 μ gk g �1 , respective- ly. The method was applied to 30 sushi samples of tuna, salmon, and kani from Campinas City, Sao Paulo State, Brazil, and the results ranged from 6.2 to 761, 1.5 to 4.0, and <1.4 to 13.5μ gk g �1 , respectively. High amounts of

Use of Wastewater from Striped Catfish (Pangasianodon hypophthalmus) Pond Culture for Integrated Rice–Fish–Vegetable Farming Systems in the Mekong Delta, Vietnam

This article investigates the feasibility of reusing wastewater from striped catfish (Pangasianodon hypophthalmus) pond culture as nutrient input for integrated rice–Nile tilapia–green bean farming systems, and to what extent this could contribute to decreasing the environmental impacts on water quality from the striped catfish industry in the Mekong Delta. Four treatments in triplicates were used to investigate the growth of rice and green bean varieties under different combinations of inorganic fertilizer and water from the river and a striped catfish pond culture. The Nile tilapia (Oreochromis niloticus) was cultured at low density without feeding in a canal adjacent to the rice field. Rice yields ranged from 3,514 to 4,023 kg ha−1 with no significant differences between treatments (p > 0.05). The yield of green bean ranged from 2,671 to 3,282 kg ha−1 (p < 0.05), with the highest yields for beans only receiving water from the striped catfish pond. The water quality concentrations decreased significantly when passing through the rice plots for almost all treatments (p < 0.05). Total phosphorus and nitrogen levels in the outflowing water were reduced by almost 50% compared to the inflowing water from the striped catfish pond. Overall, the results indicated that an integrated system generates both economic and environmental benefits as compared to monocultures.

Zebrafish (Danio rerio) eleutheroembryo-based procedure for assessing bioaccumulation.

This paper reports on the development and preliminary evaluation of a new bioaccumulation test based on the use of zebrafish (Danio renio) eleutheroembryos (72 h after hatching, corresponding to 144 h post fertilization, hpf) as an alternative to adult fish-based procedures for regulatory purposes regarding REACH application. The proposed test accomplished the OECD 305 guideline and consists of a 48 h uptake period followed by a 24 h depuration step. Bioaccumulation experiments were performed for a selected of hyper hydrophobic chemicals (log Kow> 7.6), that is, PCB 136 and PBDE 154 at two concentration levels corresponding roughly to 1% and 0.1% the chemicaĺs LC50(nominal concentrations of 4.0 and 12.0 μg/L for PCB 136, and 1.0 and 5.0 μg/L PBDE 154, respectively). Toxicokinetic models were used to calculate the bioconcentration factors (BCFs) based on of the chemical concentrations found in the contaminated eleutheroembryos and their surrounding media. The experimentally determined accumulation profiles show bioaccumulation by zebrafish eleutheroembryos of both chemicals, and that the process is more complex than simple water-lipid partition. Calculated log BCFs using a first-order accumulation model(3.97 and 3.73 for PCB 136, and 3.95 and 4.29 for PBDE 154) were in the range of those previously reported in the literature. The suitability of this new nonprotected life stage bioaccumulation protocol for BCF estimation was evaluated by application to widely divergent micropollutants with different accumulation mechanisms. The results were compared with those in the MITE-NITE database for adult rice fish (Oryzias latipes).

Can positive interactions between cultivated species help to sustain modern agriculture?

The importance of positive interactions between species within natural ecosystems and species associated with traditional agriculture is well recognized. However, modern agriculture generally depends on monocultures, where positive interactions between cultivated species (ie in which the presence of one species facilitates the survival, growth, or reproduction of other species) are largely ignored. Here, we review recent studies focused on the positive interactions between cultivated species, consider how three traditional agricultural systems (legume–cereal intercropping, rice–fish co‐culture, and agroforestry) have benefited from such interactions, and examine how these benefits are affected by climate, planting patterns, and field management. Finally, we propose a framework to illustrate how these interactions may improve modern agriculture through: the selection of species–species partnerships; the development of specialized field machinery (in each case); field structure and configuration; field management; and farmer and societal acceptance.

Gene-specific disruption of endocannabinoid receptor 1 (cnr1a) by ethanol probably leads to the development of fetal alcohol spectrum disorder (FASD) phenotypes in Japanese rice fish (Oryzias latipes) embryogenesis

The present study was designed to investigate the probable roles played by cannabinoid (CB) receptors in fetal alcohol spectrum disorder (FASD) induction in Japanese rice fish (Oryzias latipes). Searching of public databases (GenBank, Ensembl) indicated that the Japanese rice fish genome includes three human ortholog CB receptor genes (cnr1a, cnr1b and cnr2). Quantitative real-time PCR (qPCR) and whole mount in situ hybridization (WMISH) techniques were used to analyze the expression of these cnr genes during Japanese rice fish embryogenesis and also in response to developmental ethanol exposure. qPCR analyses showed that the expression of all three CB receptor genes were developmentally regulated and only cnr2 showed maternal expression. The mRNA concentrations of these genes were found to be enhanced after 3dpf and attained maximal levels either prior to or after hatching. WMISH technique indicated that all three cnr genes were expressed in the head region of hatchlings. During development, ethanol selectively attenuated the expression of cnr1a mRNA only. Blocking of cnr1a mRNA by CB1 receptor antagonists rimonabant (10–20μM) or AM251 (0.2–1μM) 0–2dpf were unable to induce any FASD-related phenotypic features in embryos or in hatchlings. However, continuous exposure of the embryos (0–6dpf) to AM251 (1μM) was able to reduce the hatching efficiency of the embryos. Our data indicated that in Japanese rice fish, ethanol disrupted the expression of only cnr1a in a concentration-dependent manner that induced delay in hatching and might be responsible for the development of FASD phenotypes.