G1 Generation Research Articles

Selective breeding for summer survival in Pacific oyster (Crassostrea gigas): Genetic parameters and response to selection

Pacific oyster (crassostrea gigas) is an economically important farmed oyster species which is now severely threatened by summer mortality all over the world. Selective breeding for natural disease resistance is an effective and sustainable method to reduce mortality outbreak. We established a basic breeding population by using two fast-growing lines and then two successive generations of selection for summer survival was conducted. The aim of this study was to estimate the genetic parameters and detect the selection response over two generations of family selection. Summer survival was defined as binary trait and analyzed by two animal models (linear animal model (LAM) and threshold (logit) animal model (TAM)). Across generations, low to moderate heritability values (0.12–0.28) were estimated for summer survival by using two different models, suggesting that this population will continue show response to future selection. The genetic correlations between summer survival and growth traits were low but positive in different generations (0.056–0.229), which implies that selection for summer survival would not result in adverse responses in growth traits. The realized genetic gain of summer survival from the G1 to G3 generation ranged from 10.71% to 13.55%. The accumulated realized genetic gain (24.26%) expressed as a percentage was 41.97%. Moreover, there were also positively correlated changes in growth traits which selected population had a higher growth than did the control population in each generation. The results indicate that there are good prospects for the genetic improvement of summer survival in C. gigas.

Efficient CRISPR/Cas9-mediated genome modification of the glassy-winged sharpshooter Homalodisca vitripennis (Germar)

CRISPR/Cas9 technology enables the extension of genetic techniques into insect pests previously refractory to genetic analysis. We report the establishment of genetic analysis in the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, which is a significant leafhopper pest of agriculture in California. We use a novel and simple approach of embryo microinjection in situ on the host plant and obtain high frequency mutagenesis, in excess of 55%, of the cinnabar and white eye pigmentation loci. Through pair matings, we obtained 100% transmission of w and cn alleles to the G3 generation and also established that both genes are located on autosomes. Our analysis of wing phenotype revealed an unexpected discovery of the participation of pteridine pigments in wing and wing-vein coloration, indicating a role for these pigments beyond eye color. We used amplicon sequencing to examine the extent of off-target mutagenesis in adults arising from injected eggs, which was found to be negligible or non-existent. Our data show that GWSS can be easily developed as a genetic model system for the Hemiptera, enabling the study of traits that contribute to the success of invasive pests and vectors of plant pathogens. This will facilitate novel genetic control strategies.

Transgenerational Effect of Drought Stress and Sub-Lethal Doses of Quizalofop-p-ethyl: Decreasing Sensitivity to Herbicide and Biochemical Adjustment in Eragrostis plana

(1) Background: Eragrostis plana Ness is a invasive C4 perennial grass in South America and very adaptable to environmental stresses. Our hypothesis is that there is a transgenerational cross-talk between environmental stresses and weed response to herbicides. This study’s objectives were to: (1) evaluate if E. plana primed by drought stress (DRY), a sub-lethal dose of quizalofop-p-ethyl (QPE), or a combination of both drought and herbicide stresses (DRY × QPE), produce a progeny with decreased sensitivity to quizalofop and (2) investigate the potential mechanisms involved in this adaptation; (2) Methods: A population of E. plana was isolatedly submitted to treatments for drought, quizalofop or drought plus quizalofop for two generations. The progenies were analyzed for sensitivity to the herbicide quizalofop and performed biochemical, chromatographic and molecular analyses.; (3) Results: In the G2 generation, the quizalofop-treated CHK population had reduced stomatal conductance and increased hydrogen peroxide and lipid peroxidation. On the other hand, there was no change in stomatal conductance, hydrogen peroxide level, and lipid peroxidation in the quizalofop-treated DRY population. In addition, this population had increased antioxidant enzyme activity and upregulated CYP72A31 and CYP81A12 expression, which was accompanied by reduced quizalofop-p-ethyl concentrations; (4) Conclusions: E. plana demonstrated a capacity for transgenerational adaptation to abiotic stresses, with the population exposed to drought stress (DRY) becoming less sensitive to quizalofop-p-ethyl treatment.

Knockout of the EgriBLOS2 gene results in the transparent integuments of Ectropis grisescens larvae

• CRISPR/Cas9-mediated EgriBLOS2 knockout resulted in larval transparent integuments of Ectropis grisescens . • As many as 70% of the transparent larvae were obtained in G0 generation. • EgriBLOS2 was involved in the formation of larval interment colors. The body colors of insects have evolved specialized roles in body protection, signaling and physiology. In some case, the larvae can camouflage their body colors to adapt the habitants and protect themselves. However, the genetic and molecular basis on larval body colors of the tea geometrid, Ectropis grisescens , remains poorly known. Here, we reported an effect of the lysosome-related organelles complex-1, subunit 2 ( EgriBLOS2 ) gene knockout on larval integuments of E. grisescens , by using a clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system. Combining transcriptomic data and PCR approaches, we first identified the EgriBLOS2 gene from E. grisescens , which encoded 137 amino acids and comprised 3 introns. In the phylogenetic analysis, EgriBLOS2 clustered in the Lepidoptera clade with high conservation to members in other lepidopteran species. Developmental expression profiles revealed that EgriBLOS2 was constantly transcribed at each stage, in which its expression was significantly lower in 2nd instar larvae than that of other instars. After injecting EgriBLOS2 -specific guide RNA and Cas9 messenger RNA into eggs, 70% of larvae showed the translucent integuments in G0 generation, with an emphasis on black splayed patterns in the 2nd and 8th segments of abdomens. However, some typical characteristics of larvae were not obviously changed in mutant instars, such as ocelli, mouthparts and other appendants. This study has unraveled the roles of EgriBLOS2 in the formation of larval integument colors, and provides an alternative strategy for pest management based on the colors in this species .

Glucosamine-6-phosphate N-acetyltransferase gene silencing by parental RNA interference in rice leaf folder, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)

Parental RNAi (pRNAi) is a response of RNA interference in which treated insect pests progenies showed a gene silencing phenotypes. pRNAi of CmGNA gene has been studied in Cnaphalocrocis medinalis via injection. Our results showed significant reduction in ovulation per female that was 26% and 35.26% in G1 and G2 generations, respectively. Significant reduction of hatched eggs per female were observed 23.53% and 45.26% as compared to control in G1–G2 generations, respectively. We also observed the significant variation in the sex ratio between female (40% and 53%) in G1–G2 generations, and in male (65%) in G1 generation as compared to control. Our results also demonstrated the significant larval mortality (63% and 55%) and pupal mortality (55% and 41%), and significant reduction of mRNA expression level in G1 and G2 generations. Our findings have confirmed that effectiveness of pRNAi induced silencing on the CmGNA target gene in G1–G2 generations of C. medinalis. These results suggested the potential role of pRNAi in insect pest resistance management strategies.

CRISPR/Cas9 mediated sex-ratio distortion by sex specific gene editing in Aedes aegypti

Aedes aegypti is a principal vector for several viruses including dengue virus, chikungunya virus and zika virus. Economic burden of mosquito-borne diseases, relative failure of traditional control strategies and the resistance development against insecticides enforces towards genetic manipulation of Ae. aegypti. Hence, a key gene doublesex (Aedsx) which regulate sex differentiation and alternatively splices to form male and female specific transcripts (AedsxM and AedsxF). CRISPR/Cas9 technique was employed to sex specifically disrupt the female-specific isoforms, AedsxF1 and AedsxF2, both of which were shown to be expressed only in female mosquitoes. Targeting of dsxF at the developmental stage has resulted in various phenotypic anomalies of adult females. The rate of adult mutation phenotype was recorded between 29 and 37% along with anomalies of wing size, proboscis length and reduction in the sizes of pre-blood-meal and after blood-meal ovaries in dsxF1 and dsxF2 microinjected groups, respectively. These findings can be correlated with reduced fecundity rate of Go female, where AedsxF1 and AedsxF2 groups showed reduction rate in range of 23–31%. Furthermore, hatching inhibition rate of 28 to 36% was also observed in G1 generation when compared to the wildtype. Overall, these results demonstrated that AedsxF disruption has resulted in multiple female traits disruption including decreased fertility of the female that could directly or indirectly associated with reproduction and its disease transmitting abilities. All these findings suggesting that CRISPR works to alter the developmental pathways as predicted, and therefore this method potentially gives us the basis for the sex-ratio distortion system as genetic control approach for the management of this vector.

Comparison of biological characteristics of the predatory mite Blattisocius mali (Acari: Blattisocidae) reared on frozen eggs of Tyrophagus putrescentiae (Acari: Acaridae) alone and in combination with cattail and olive pollens

Blattisocius mali (Oudemans), known as a predator of some species of storage pest mites, was reared on frozen eggs of Tyrophagus putrescentiae (Schrank) alone (Tp) but also supplemented with cattail (Tp + cattail) and olive (Tp + olive) pollen. Life table parameters of B. mali were evaluated in the first (G1), eighth (G8) and sixteenth (G16) generation on the three different diets. Survival of the immatures of the predator was not affected by the tested diets, whereas it significantly differed among generations. The highest and lowest mortality was observed in the G8 and G1 generations, respectively, on all diets. Except for the total pre-oviposition period (TPOP) and the adult pre-oviposition period (APOP), all life table parameters of B. mali were affected by the different diets; In G1, supplementation of (Tp) with both pollens significantly increased the fecundity, oviposition period and female life span of B. mali. Population growth parameters of the predator like intrinsic rate of increase (r), net reproductive rate (R0) and finite rate of increase (λ) significantly increased with the supplementation of (Tp) with cattail pollen. However, in G8 and G16, B. mali reared on the two combinations significantly showed the lowest values of oviposition period, female and male life span and mean generation time (T) (only F8). Except for female and male developmental times and TPOP, other biological parameters of B. mali significantly differ across generations. Adding both pollens to the frozen eggs of the prey mite, significantly decreased fecundity, oviposition period, female and male life span and population parameters such as (r), (T), (λ) of B. mali in G16 compared with G1. With comparison of the effects of diet through the generations on biological and population parameters of B. mali, it is concluded that frozen eggs of T. putrescentiae is strongly advisable for mass-rearing of the predator and mixed frozen diets (containing pollen) is suggested as supplemental diet for establishment of the predator after release.

Comparison of phenotypic and heterotic effects affecting milk yield, composition and udder morphometry of Hair and F1, F2 and G1 generation cross-breeds of Alpine × Hair and Saanen × Hair dairy goats in a semi-intensive system.

This study was conducted to compare milk yield, milk components and udder traits of Hair goat, F1, F2 and G1 generation cross-breeds of Alpine × Hair and Saanen × Hair goats under a semi-intensive system. The effects of genotype, parity, flock and year on milk production, physical and chemical compositions were almost all significant (between p < 0.05 and p < 0.001). The F1, F2 and G1 generations produced 24 and 44% higher (p < 0.001) lactation milk yield (LMY), 12 and 35% (p < 0.001) fat yield and 19 and 35% (p < 0.001) protein yield than Hair goat. Positive heterosis was found in milk production and contents both Alpine × Hair F1 (AHF1) and Saanen × Hair F1 (SHF1) generations. The heterotic effect of the LMY was significant in the SHF1 generation (p < 0.05), but not in the AHF1 generation. The highest correlation was found between LMY and udder circumference and then udder volume (p < 0.001; r = from 0.34 to 0.75). The coefficient of determination of the obtained equation for the estimation of the LMY in the Hair and cross-bred goats ranged from 0.48 to 0.71. These results showed that as the level of cross-breeding increased in this semi-intensive system, better quality dairy products can be obtained from goats, and udder measurements can be a helpful tool in estimating milk yield, thus reducing the pressure on the ecosystem. Thus, it was concluded that with better modelling of environmental variations, milk production characteristics of local goats can be increased much faster by cross-breeding, especially at the F1 and G1 generation cross-breed levels.

The effect of photocopier types on line quality features of handwriting in multi-generational photocopies

The present research was aimed at finding out the relative effect of advancement in photocopier technology on the analysis of handwriting line quality features in multi-generational photocopies. Five subsequent multi-generational photocopies of 50 signature samples from different individuals which were produced by 75 black and white photocopiers were used for line quality assessments. Variations in line quality features in different photocopy generations, such as: smooth edges or ragged edges, broken or continuous stroke, fine tapering changes, and some identification details of features like pen lifts, retouching, and hesitation were carefully observed in sample photocopies, which were recorded according to the brand and model of photocopier machines, as well as their size and speed. The results of the study revealed that raggedness in line was often observed in third generation (G3) and higher generations, in samples produced by some low speed copiers (copying speed &lt; 30 cpm) or very high speed copiers (copying speed ≤ 80 cpm). However, their line quality was still found to be good enough for handwriting analysis up to the fifth generation (G5) in photocopy samples produced by some medium speed copiers (copying speed 30 to 50 cpm). It was, however, observed that, usually, continuity of line and smoothness of line were appreciably lost in G3 and higher generations in photocopies which were produced by portable desktop printers. Exceptionally, certain artifacts that are usually found in some higher generation copies were conspicuously absent in all photocopy generations (G1–G5) which were produced by some advanced third generation photocopiers. Hopefully, the information obtained from the study will be found useful to document examiners when examining certain cases involving multi-generations of photocopier reproductions.

Gene Transmission, Growth, and Exogeneous Growth Hormone Expression of G2 Transgenic Betta Fish (Betta imbellis)

Highlight ResearchThe F2 of GH-transgenic B. imbellis was successfully producedThe transgene inheritance by the F2 fish was more than 90%The growth and body size of transgenic fish was significantly higher than controlF2 fish reached a larger body size in a shorter period compared to the F1 AbstractIn our previous research, we had successfully produced G0 and G1 Pangasianodon hypophthalmus growth hormone (PhGH) transgenic B. imbellis, native ornamental betta from Indonesia, which its giant-sized variant has valuable price for the breeders. The G0 and G1 transgenic (TG) fish showed higher growth rate and body size compared to the non-transgenic (NT) fish. The study was aimed to produce and evaluate the consistencies of transgene transmission and expression in G2 generation. The growth rate and body size between TG and NT fish was also compared. The G2 generation was produced using crosses between TG and NT G1 fish: ♂TG × ♀TG, ♂TG × ♀NT, ♂NT × ♀TG, and ♂NT ×♀ NT. Fish were reared for 12 weeks, and transgene detection was performed using the polymerase chain reaction method (PCR) on isolated DNA from the caudal fin clips. The endogenous and exogenous GH expression analysis was conducted using the quantitative real-time PCR (qPCR) method. The results showed that the inheritance of the GH transgene by the G2 fish was more than 90% in all transgenic crosses. Endogenous GH was expressed at the same levels in the brain of TG and NT fish, but the exogenous GH expression was highly detected only in the TG fish. The G2 transgenic fish had a higher specific growth rate, up to 31%, compared to the control. The body length of TG crosses were 23−35% higher and had 111−135% higher body weight compared to NT fish. These results showed a promising approached in mass-producing stable lines of giant-sized betta using the GH-transgenic technology.

Identification of yellow gene family and functional analysis of Spodoptera frugiperda yellow-y by CRISPR/Cas9

For a devastating agricultural pest, functional genomics promotes the finding of novel technology to control Spodoptera frugiperda, such as the genetics-based strategies. In the present study, 11 yellow genes were identified in Spodoptera frugiperda. The transcriptome analysis showed the tissue-specific expression of part yellow genes, which suggested the importance of yellow genes in some biological processes in S. frugiperda, such as pigmentation. Among these yellow genes, the expression profiles of yellow-y gene showed that it was expressed in all life stages. In order to realize the further study of yellow-y, we employed CRISPR/Cas9 system to knock out this gene. Following knock out, diverse phenotypes were observed, such as color changes in both larvae and adults. Different from the wild-type larvae and adults, G0 mutants were yellowed since hatching. However, no color difference was observed with the pupal cuticle between the wild-type and mutant pupae before the 8th day. On the basis of the single-pair strategy of G0 generation, the yellow-y gene was proved to be a recessive gene. The G1 yellowish larvae with biallelic mutations displayed a relatively longer development period than wild-type, and often generated abnormal pupae and moths. The deletion of yellow-y also resulted in a decline in the fecundity. The results revealed that yellow-y gene was important for S. frugiperda pigmentation, as well as in its development and reproduction. Besides, the present study set up a standard procedure to knock out genes in S. frugiperda, which could be helpful for our understanding some key molecular processes, such as functional roles of detoxification genes as insecticide resistance mechanisms or modes of action of insecticides to facilitate the management of this insect pest.

CRISPR/Cas9-mediated pou4f3 knockout induces defects in the development of the zebrafish inner ear

Abstract Objective: The zebrafish is an excellent model for studying gene function in auditory system development. Pou4f3 plays an important role in mouse hair cell formation. Here, we constructed a pou4f3-knockout Tg(Brn3c:GFP) zebrafish to provide an efficient fluorescence-visualized model for studying the molecular mechanisms of ear development. Methods: Cas9/single guide RNAs targeting exon 2 of pou4f3 were designed and injected into one-cell stage zebrafish embryos (G0 generation). The G0 generation were crossed with Tg(Brn3c:GFP) zebrafish to obtain pou4f3-mutant Tg(Brn3c:GFP) zebrafish. The targeting efficiency was detected by polymerase chain reaction amplification and Sanger sequencing. Zebrafish hair cells were observed by laser scanning confocal microscopy in vivo. The morphology of the otoliths and semicircular canals were analyzed. All animal experiments were approved by the Animal Care and Use Committee of Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University (approval No. 2016-KY-040) on March 3, 2016. Results: The pou4f3-mutant Tg(Brn3c:GFP) zebrafish line was successfully established. Fluorescence observation suggested that hair cell development was delayed in pou4f3-knockout zebrafish. Knockout of pou4f3 also induced defects in the otoliths and semicircular canals and impaired ear function in zebrafish. Conclusion: A CRISPR/Cas9-mediated pou4f3 mutant Tg(Brn3c:GFP) zebrafish model was established for the first time to demonstrate the essential role of pou4f3 in zebrafish ear development. Our study provides a highly efficient method for the establishment of a visualized model of gene knockout zebrafish and has the potential to allow high-throughput drug screening to explore therapeutics for related diseases.

Screening and validation of genome-edited animals.

The emergence of an array of genome-editing tools in recent years has facilitated the introduction of genetic modifications directly into the embryo, increasing the ease, efficiency and catalogue of alleles accessible to researchers across a range of species. Bypassing the requirement for a selection cassette and resulting in a broad range of outcomes besides the desired allele, genome editing has altered the allele validation process both temporally and technically. Whereas traditional gene targeting relies upon selection and allows allele validation at the embryonic stem cell modification stage, screening for the presence of the intended allele now occurs in the (frequently mosaic) founder animals. Final confirmation of the edited allele can only take place at the subsequent G1 generation and the validation strategy must differentiate the desired allele from a range of unintended outcomes. Here we present some of the challenges posed by gene editing, strategies for validation and considerations for animal colony management.

The GWAS Analysis of Body Size and Population Verification of Related SNPs in Hu Sheep.

Body size is an important indicator of growth and health in sheep. In the present study, we performed Genome-Wide Association Studies (GWAS) to detect significant single-nucleotide polymorphisms (SNPs) associated with Hu sheep’s body size. After genotyping parental (G1) and offspring (G2) generation of the nucleus herd for meat production of Hu sheep and conducting GWAS on the body height, chest circumference, body length, tail length, and tail width of the two groups, 5 SNPs associated with body height and 4 SNPs correlated with chest circumference were identified at the chromosomal significance level. No SNPs were significantly correlated to body length, tail length, and width. Four out of the 9 SNPs were found to be located within the 4 genes. KITLG and CADM2 are considered as candidate functional genes related to body height; MCTP1 and COL4A6 are candidate functional genes related to chest circumference. The 9 SNPs found in GWAS were verified using the G3 generation of the nucleus herd for meat production. Nine products were amplified around the 9 sites, and 29 SNPs were found; 3 mutation sites, G > C mutation at 134 bp downstream of s554331, T > G mutation at 19 bp upstream of s26859.1, and A > G mutation at 81 bp downstream of s26859.1, were significantly correlated to the body height. Dual-luciferase reporter gene experiments showed that the 3 SNPs could significantly impact dual-luciferase and gene transcription activity.

CRISPR/Cas9-mediated mutagenesis reveals the roles of calaxin in gastropod larval cilia.

Obtaining detectable knockout phenotypes in the G0 generation is essential for gene function studies. Although CRISPR/Cas9-mediated gene editing has been employed to knock out molluscan genes, detectable phenotypes in the G0 generation have not been reported in these animals. In this study, we determined the knockout phenotype of a cilium-related gene, calaxin, using CRISPR/Cas9 technology in the gastropod mollusk Lottia goshimai. Injections with the Cas9-sgRNA complex caused approximately 30-80% of the injected larvae to exhibit a short-cilia phenotype characteristic of shortened cilia and decreased motility in the larvae. This phenotype was detectable in the G0 generation and was consistent for two independent sgRNAs. Genotyping of the injected larvae revealed various types of deletions and insertions in the target gene, which occurred in all sequences from the short-cilia larvae. This result indicated that the short-cilia phenotype was indeed caused by calaxin knockout. This possibility was supported by an RNAi assay targeting calaxin, which produced a highly similar short-cilia phenotype. We observed that a single SNP in the target sequences of the sgRNAs could show varied effects on the efficiency of mutagenesis. These results help to establish a foundation for future studies on molluscan gene editing using the CRISPR/Cas9 technique and contribute to the body of knowledge on molluscan ciliary functions.

Droplet digital PCR or quantitative PCR for in-depth genomic and functional validation of genetically altered rodents.

Gene targeting and additive (random) transgenesis have proven to be powerful technologies with which to decipher the mammalian genome. With the advent of CRISPR/Cas9 genome editing, the ability to inactivate or modify the function of a gene has become even more accessible. However, the impact of each generated modification may be different from what was initially desired. Minimal validation of mutant alleles from genetically altered (GA) rodents remains essential to guarantee the interpretation of experimental results. The protocol described here combines design strategies for genomic and functional validation of genetically modified alleles with droplet digital PCR (ddPCR) or quantitative PCR (qPCR) for target DNA or mRNA quantification. In-depth analysis of the results obtained with GA models through the analysis of target DNA and mRNA quantification is also provided, to evaluate which pitfalls can be detected using these two methods, and we propose recommendations for the characterization of different type of mutant allele (knock-out, knock-in, conditional knock-out, FLEx, IKMC model or transgenic). Our results also highlight the possibility that mRNA expression of any mutated allele can be different from what might be expected in theory or according to common assumptions. For example, mRNA analyses on knock-out lines showed that nonsense-mediated mRNA decay is generally not achieved with a critical-exon approach. Likewise, comparison of multiple conditional lines crossed with the same CreERT2 deleter showed that the inactivation outcome was very different for each conditional model. DNA quantification by ddPCR of G0 to G2 generations of transgenic rodents generated by pronuclear injection showed an unexpected variability, demonstrating that G1 generation rodents cannot be considered as established lines.

Growth hormone transgenesis and feed composition influence growth and protein and amino acid content in transgenic G3 mutiara catfish (Clarias gariepinus)

Clarias gariepinus growth hormone (CgGH) transgenesis was previously used to develop a population of second-generation (G2) transgenic mutiara catfish (C. gariepinus). The third generation of these fish (1-month old fingerlings) had 2–3 times improvement in growth compared to non-transgenic fish in the commercial feed test for 6 weeks of rearing. We assessed the impact of CgGH transgene expression on growth and protein and amino acid content of the G3 generation of these transgenic mutiara catfish relative to non-transgenic catfish. Since variation in composition of feed mixes can affect protein and amino acid content of fish, we tested three mixtures of commercial feed and boiled tuna (Euthynnus affinis): feed A (50:50 feed to tuna), B (65:35), and C (80:20) to transgenic catfish. Feed A* (50:50) was fed as a control to non-transgenic catfish. Feed efficiency, including feed conversion ratio and protein use efficiency (i.e., protein retention and protein productive value), was assessed. Feed efficiency, protein content, and essential amino acid content in G3 transgenic catfish (feed A and B) were higher than in non-transgenic fish (feed A*). The latter were deficient in lysine and methionine. Transgenic catfish fed with feed C (80:20) showed lysine deficiency and lower growth than fish fed feeds A and B. Feed B (65:35) was the optimal feed mixture utilized; it increased growth, protein levels, and feed conversion efficiency in G3 catfish. The growth of transgenic fish was higher than non-transgenic fish when supported by feeding with balanced nutrients.

Determination of relative economic weights of growth and egg production traits in Nigerian indigenous chicken

The relative economic weight (REW) of a trait is the additional gain/loss from a unit change in the trait relative to other traits in an individual. They are used to calculate aggregate economic values for purposes of genetic improvement in animals. The present study was designed to evaluate the bio-economic variables of growth and 16 weeks egg production parameters: egg number (EN16) egg weight (EWT16) body weight at first egg (BWTFE), body weight at 16 week of lay (BWTE16), cost of feed, and revenue from eggs and chicken carcass, 16 feed conversion ratio (FCR ), and body weight gain (BWG16) in the Nigerian indigenous chicken, and to determine the economic weights (EW) and REW of EN16, EWT16 and BWTE16 for G0, G1, and G2 generations. A total of 250 pullets (20 week old, point of lay) from a population of heavy body weight local chickens were used for the study. The birds were housed individually in cages, fed optimally on layers mash (G and G : 100g/bird/day; G : 0 1 2 125g/bird/day) and given water ad libitum. Data included EN , EWT , BWTE , BWTFE, 16 16 16 and prices of feed, eggs and spent hens, FCR , and BWG . Data on EN , EWT , BWTE , 16 16 16 16 16 and BWTFE were compared across generations using ANOVAand with other variables were used to generate the EW of the traits. The EW were then standardized relative to that of BWTE . Results showed that EW and REW of EN , EWT , and BWTE were 7.47 and 3.15, 16 16 16 16 13.67 and 5.77 and -2.37 and -1.00, respectively in G ; 13.07 and 3.82, 23.69 and 6.93, and - 0 3.42 and -1.00, respectively in G ; 16.80 and 2.89, 30.75 and 5.28 and -5.82 and -1.00, 1 respectively in G generation. Thus EN and EWT enhanced while BWTE depressed the 2 16 16 16 worth of the hen as a layer. EWT was more important than EN and both were more 16 16 important than BWTE economically. Therefore, EWT and EN are the major bio-economic 16 variables of the local hen as an egg chicken.

Reproductive performance in successive generations of the brine shrimp Artemia salina (Crustacea: Anostraca) from the Sebkha of Sidi El Hani (Tunisia)

Artemia salina cysts collected from the Sebkha of Sidi El Hani hatched and cultivated in the laboratory were investigated. Nauplii were acclimated to laboratory conditions until reproductively mature (Generation 1; G1). Reproductive performance in terms of total cysts and nauplii offspring, days between brood production, and cyst and nauplii numbers was evaluated. Nauplii produced by specimens in the G1 were defined as those of G2 with there also being third (G3) and fourth (G4) generations. The aims were to evaluate Artemia salina in aquaculture conditions with the long-term aim of developing a system for “artemiculture”. There was a larger number of cysts or nauplii per brood between G1 (60.7 ± 10.9 nauplii or cysts/female) and subsequent generations, notably G2 (122 nauplii or cysts/female, P < 0.05). The mean number of cysts and nauplii per female increased from the first and last brood. Number of cysts produced per female increased markedly (P < 0.05) from G1 (54.5 ± 14.2) to G3 (128.9 ± 39.2). Percentage of females producing nauplii increased from G1 (20 %) to G4 (100 %). There was, therefore, an increase in percentage of ovoviviparous offspring (nauplii) per female (P < 0.05) from G1 (7%) to G4 (71 %). There were no differences, however, between mean numbers of broods per female, and numbers of days between broods. The results indicate there are variations in reproduction from oviparity to ovoviviparity as consecutive generations of Artemia salina are cultivated. In summary, there was a rapid adaptation of Artemia salina of Sidi El Hani to laboratory conditions.

Growth, survival and fatty acids profile of sea urchins, Paracentrotus lividus juveniles fed with Ulva spp. and maize in aquaculture production. First results using G1 generation in Portugal

Growth, survival and fatty acids profile of sea urchins, Paracentrotus lividus juveniles fed with Ulva spp. and maize in aquaculture production. First results using G1 generation in Portugal