Crossbreeding Strategy Research Articles

Insight into the nuclear distribution patterns of conidia and the asexual life cycle of Polyporus umbellatus

P. umbellatus sclerotium is a traditional Chinese medicine that is widely utilized in China, Korea, Japan, and other countries due to its diverse medicinal activities, such as diuretic, antitumor, anticancer, and immune system enhancement effects. Conidia, which are common asexual spores in various fungi, are not universally present in Polyporus species. In this study, the asexual life cycle of P. umbellatus was elucidated. Conidia, i.e. arthorconidia, were produced by both dikaryotic and monokaryotic strains. In the dikaryotic strain, binucleate, uninucleate, and nuclei-free conidia were identified with proportions of 67.9%, 12.4%, and 19.7%, respectively. Conversely, the monokaryotic strain did not produce binucleate conidia. This discrepancy suggests that binucleate spores are heterokaryons, while uninucleate spores are homokaryons. Clamp connections were observed in dikaryotic hyphae, but were absent in monokaryotic hyphae. Monokaryotic strains were obtained from conidia of the dikaryotic strain. Additionally, mating types were determined through pairing tests, and successful crossbreeding occurred between monokaryotic strains derived from conidia and basidiospores from different strains. This study introduced the first crossbreeding strategy for P. umbellatus.

Rapid and dynamic detection of endogenous proteins through in locus tagging in rice

Understanding the behavior of endogenous proteins is crucial for functional genomics, yet their dynamic characterization in plants presents substantial challenges. Whereas mammalian studies have leveraged in locus tagging with the luminescent HiBiT peptide and genome editing for rapid quantification of native proteins, this approach remains unexplored in plants. Here, we introduce the in locus HiBiT tagging of rice proteins and demonstrate its feasibility in plants. We found that although traditional HiBiT blotting works in rice, it failed to detect two of the three tagged proteins, a result attributable to low luminescence activity in plants. To overcome this limitation, we engaged in extensive optimization, culminating in a new luciferin substrate coupled with a refined reaction protocol that enhanced luminescence up to 6.9 fold. This innovation led to the development of TagBIT (tagging with HiBiT), a robust method for high-sensitivity protein characterization in plants. Our application of TagBIT to seven rice genes illustrates its versatility on endogenous proteins, enabling antibody-free protein blotting, real-time protein quantification via luminescence, in situ visualization using a cross-breeding strategy, and effective immunoprecipitation for analysis of protein interactions. The heritable nature of this system, confirmed across T1 to T3 generations, positions TagBIT as a powerful tool for protein study in plant biology.

DRR Dhan 65 (IET 27641) – A High Yielding Low Soil Phosphorous Tolerant and Climate Resilient Rice Variety Developed from Wild Introgression Lines

The wild species of Oryza are an important source of genetic variability for the improvement of yield and tolerance to biotic and abiotic stresses. Phosphorus (P) is the second most important key nutrient, vital for plant growth and development at all stages. Phosphorous deficiency is one of the factors limiting rice yields and farmer’s profitability so it is necessary to identify genotypes with stable yield and tolerance to P deficiency. Keeping in view the unlimited potential of wild species for yield enhancement and stress tolerance, interspecific population between Oryza rufipogon in the back ground of Oryza sativa genotype KMR3 was developed by advanced back cross breeding strategy. DRR Dhan 65 (IET 27641) (RP Bio 4919-B-B NSR86) is an interspecific wild introgression line, a derivative of KMR 3 / O rufipogon with short bold grains which is high yielding under both normal and low soil phosphorous conditions. It has seed to seed maturity of 130- 135 days and gives an average yield of 6.5 t/ ha (under normal conditions; 60 kg/ha of P, i.e., recommended dose) and 4.7 t/ ha (under low Phosphorus; 40 kg/ha of P). It was released for cultivation in Andhra Pradesh, Telangana, Karnataka, Chhattisgarh, Jharkhand and Maharashtra states through Central Sub-committee on Crop Standards, Notification and Release of Varieties for Agricultural Crops vide S.O. 4065(E) dated 31st August, 2022 [CG-DL-E-31082022-238490].

Developmental cardiotoxicity of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) in marine medaka (Oryzias melastigma)

The application of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) as an antifouling biocide causes high toxicity to non-target marine organisms. To examine the developmental cardiotoxicity and mechanisms of DCOIT, we concurrently performed sub-chronic exposure and life-cycle exposure experiments using marine medaka embryos. After sub-chronic exposure to DCOIT at 1, 3, 10, and 33μg/L, cardiac defects were caused by upregulation of cardiac gene transcriptions, decreasing heart size, and accelerating heartbeat. Hyperthyroidism in medaka larvae was identified as the cause of developmental cardiotoxicity of DCOIT sub-chronic exposure. In addition, parental life-cycle exposure to 1, 3, and 10μg/L DCOIT led to transgenerational impairment of cardiogenesis in offspring medaka. A crossbreeding strategy discriminated a concentration-dependent mechanism of transgenerational cardiotoxicity. At 1μg/L, the DCOIT-exposed female parent transferred a significantly higher amount of triiodothyronine (T3) hormone to offspring, corresponding to an accelerated heart rate. However, DCOIT at higher exposure concentrations modified the methylome imprinting in larval offspring, which was associated with cardiac dysfunction. Overall, the findings provide novel insights into the developmental cardiotoxicity of DCOIT. The high risks of DCOIT-even at environmentally realistic concentrations-raise concerns about its applicability as an antifoulant in a marine environment.

Crossbreeding of two populations of Ruditapes philippenarum reveals high growth and survival heterosis

Crossbreeding of two populations of Ruditapes philippenarum reveals high growth and survival heterosis

Achieving of high-diet-fiber barley via managing fructan hydrolysis

High fructan content in the grain of cereals is an important trait in agriculture such as environmental resilience and dietary fiber food production. To understand the mechanism in determining final grain fructan content and achieve high fructan cereal, a cross breeding strategy based on fructan synthesis and hydrolysis activities was set up and have achieved barley lines with 11.8% storage fructan in the harvested grain. Our study discovered that high activity of fructan hydrolysis at later grain developmental stage leads to the low fructan content in mature seeds, simultaneously increasing fructan synthesis at early stage and decreasing fructan hydrolysis at later stage through crossing breeding is an efficient way to elevate grain diet-fiber content. A good correlation between fructan and beta glucans was also discovered with obvious interest. Field trials showed that the achieved high fructan barley produced over seven folds higher fructan content than control barley and pull carbon-flux to fructan through decreasing fructan hydrolysis without disruption starch synthesis will probably not bring yield deficiency.

The effects of upgrading and intersecting cross-breeding strategies on the geese economic traits

Routine, upgrading, and intersecting cross-breeding strategies are three methods frequently used in poultry breeding. But, till now, comparative assessment of the effects on the improvement of geese economic traits with these strategies is largely unknown. Here, using Carlos goose and Zi goose, these three strategies were employed and compared. The main economic traits, including egg production capability, egg quality, growth performance, meat production capability, and down feather production capability were all measured systematically. For egg production capability and egg quality, the upgrading group had the highest egg-laying rate, and the intersecting group had the biggest egg size compared with the routine group (p < 0.05). No significant difference was observed in the egg shape index (p > 0.05). The routine group had the best fertility and hatchability (p < 0.05). For growth performance, the intersect group had the biggest hatch weight (p < 0.05), and the upgrading group had the fastest growth rate (p < 0.05). For meat production capability and down feather production capability, no significant difference was observed (p > 0.05). We found that different cross-breeding strategies had different superiority on economic traits. The economic value of each economic trait should be taken into account so that an optimized cross-breeding strategy could be made to get the most of the benefits.

Conservation of a native dairy cattle breed through terminal crossbreeding with commercial dairy breeds

ABSTRACT Farmers play a key role in conserving native livestock breeds, but without economic support, farms with native breeds may not be viable. We hypothesized that terminal crossbreeding can improve herd economy and decrease the economic support needed from society. Three scenarios were simulated using SimHerd Crossbred: a herd of purebred Swedish Polled Cattle, a herd of purebred Swedish Red, and a herd of 75% Swedish Polled Cattle and 25% F1 crossbreds. The results showed annual contribution margin per cow in the herd can be increased by €181 by crossbreeding compared with pure-breeding with the native breed, giving a 13.6% growth in contribution margin. However, the needed cost in subsidies paid by the government will remain unchanged if the population size of the native breed is to be maintained. Combining a crossbreeding strategy with the marketing of niche products may facilitate the conservation of native cattle.

Sound absorption and thermal insulation characteristics of fabrics made of pure and crossbred sheep waste wool

Abstract Waste wool fiber is a potential source for thermal and acoustical applications due to its natural properties. This work aims to investigate the potential of crossbreeding for the engineering of the sound absorption and thermal insulation properties of the waste wool. At first, a crossbreeding strategy was performed on the local sheep called Ghezel (Gh) thick-wool with Arkharmerino (Ar) fine-wool, and the procedure was continued up to two races (ArGh1 and ArGh2). Afterward, the wool fibers were collected from all four breeds, and the short fibers were removed as the waste. The chemical and morphological analyses were carried out on the fibers. The waste fibers were then spun and used as weft yarns to weave the woolen fabrics. The sound absorption and thermal insulation properties of the fabrics were also investigated. Additionally, the frequency-dependent sound absorption coefficient (SAC) of samples was predicted using the Mechel model. The results showed that the crossbreeding of Gh with Ar results in improvement of fiber fineness, which in turn positively affects the sound absorption behavior of the fabrics. There was a good adoption between the experimental and predicted results, indicating the high accuracy of the Mechel model for the woolen woven fabrics. The results also indicated that fabrics made from coarser fibers show better thermal insulation performance. The results indicated that waste wool as an environmentally friendly thermal insulation material has comparable acoustical and thermal characteristics to mineral/wools and glass fiber-based materials, with the advantage of being ecological and simultaneously economical, biodegradable, and abundant.

Systematic crossbreeding and its impact on carcass parameters and associated meat quality properties in goats and sheep

The major focus of any commercial goat and sheep enterprise is to maximize on carcass and meat production and obviously realizing substantial gain in profits. In modern goat and sheep meat production, crossbreeding has become an admissible and accelerated strategy to produce carcasses that ensure the point of departure for leaner meat, in addition to consumer acceptable carcass properties. I has become a norm that genetic manipulation for desired carcass and meat quality in small ruminants can be achieved through crossbreeding. There is considerable individual, maternal and paternal heteroses for carcass and meat quality properties in goat/ sheep crosses. In this regard, crossing of genetic distant goat/sheep breeds fortifies the degree of manifestation of carcass and meat quality performance results. In practice noticeable commercial gains have been achieved in improving carcass and meat quality properties through crossing indigenous and exotic goats’/sheep breeds, especially in low input production systems. It should be noted that the inconsistency on end results on the impact of crossbreeding on carcass and meat quality parameters is due to various non-genetic factors that are experienced in different production systems. Carcass and meat value is influenced by a significant number of different factors where the uttermost importance are genotype, nutrition, sex, age and weight at slaughter and management. In this case, comparability of results of crossbreeding on carcass and meat quality performance in different production systems have been debatable and complicated, due to the fact that in certain cases crossbred animals are slaughtered at the same age and varied sex, and/or different age and same sex, possibly differing in weight at slaughter. The differentiated nutritional management in extensive versus intensive production systems is critical in determining the quality carcass and/or meat in crossbred goat and sheep. Consumers have been the major prescribers of the intended form of carcass and meat quality proponents’ world over, especially in developed countries. In this regard crossbreeding has been strategically used to customise meat production to the needs of various production systems, in terms of carcass and meat attributes seem acceptable by different host markets and consumers’ expectations. However, it has been acknowledged that not necessarily every crossing is adapted for breeding to guarantee comparable desired carcass and meat quality parameters, hence different combination of two-breed and to a lesser extent three-breed crossing of selected populations of goats and sheep have been used to carter for the needs of different production systems and markets. Against this background, the application of any systematic crossbreeding strategy should take into account the appropriate breed combination by selecting right population to fulfill efficient goat/sheep meat production. Crossbreeding capitalize on genetic distance through utilizing superior specialized maternal and paternal breeds/lines for the purpose of maximizing their superiority, diluting their flaws for improved performance in carcass and meat quality parameters. Basically, crossbreeding is not one size fits all, in conformity with expanded genetic diversity of goat and sheep breeds being used in differentiated production systems, accordingly no one combination of specific goat/sheep breeds will work for multiple production systems. The purpose of the present review is to give an insight on the impact of crossbreeding on carcass and meat quality parameters in goats and sheep.

Economic consequences of dairy crossbreeding in conventional and organic herds in Sweden

This study simulated the consequences of crossbreeding between Swedish Holstein and Swedish Red on herd dynamics and herd profitability under Swedish conditions. Two base herds were simulated using a stochastic herd simulation model, SimHerd Crossbred. The herds reflected average Swedish conventional and organic herds having purebred Swedish Holstein. For each base herd, 3 breeding strategies were simulated: pure-breeding, 2-breed terminal crossbreeding, and 2-breed rotational crossbreeding. The terminal crossbreeding strategy implied having a nucleus of Swedish Holstein and a proportion of F1 Swedish Red × Swedish Holstein crossbred cows within the same herd. The crossbreds in this herd did not produce replacement heifers but exclusively beef × dairy cross calves. Beef semen was also used in the pure-breeding (10-20% in cows) and the rotational crossbreeding (40% in cows) strategies to retain a limited surplus of replacement heifers. To ensure an adequate number of crossbreds in the terminal crossbreeding strategy, X-sorted sexed semen was used for insemination in all the purebred heifers. The outcome was 67% purebred and 31% F1 crossbreds in the herd. In addition, 31% heterosis was expressed compared with 67% heterosis expressed using a 2-breed rotational crossbreeding strategy. Compared with the pure-breeding strategy, crossbreeding increased the annual contribution margin per cow by €20 to €59, with the rotational crossbreeding strategy creating the largest profitability. The increased profitability was mainly due to improved functional traits, especially fertility. For the conventional production system, the replacement rate was 39.3% in the pure-breeding strategy and decreased to 35.8 and 30.1% in the terminal and rotational crossbreeding strategy, respectively. Similar changes happened in the organic production system. Additionally, the crossbreeding strategies earned €22 to €42 more annually per cow from selling live calves for slaughter due to the extended use of beef semen. Milk production was similar between pure-breeding and terminal crossbreeding, and only decreased 1 to 2% in rotational crossbreeding. These results show that crossbreeding between Swedish Holstein and Swedish Red can be profitable in both conventional and organic Swedish herds using the strategies we have simulated. However, some aspects remain to be investigated, such as the economically optimal breeding strategy, genetic improvement, and transition strategies.

Parental Exposure to Perfluorobutanesulfonate Impairs Offspring Development through Inheritance of Paternal Methylome.

Perfluorobutanesulfonate (PFBS), an environmental pollutant of emerging concern, significantly impairs offspring development and overall health after parental exposure. However, the true inducer of offspring developmental defects among the complexity of parental influences remains unknown. In the present study, marine medaka (Oryzias melastigma) were exposed to environmentally realistic concentrations of PFBS (0, 1, 3, and 10 μg/L) for an entire life cycle. By mixing and mating control and exposed medaka (male or female), a crossbreeding strategy was employed to produce offspring eggs from various crossbreeds, with the aim of differentiating the maternal and paternal influences. Measurements of swimming performance in larval offspring showed that larvae of exposed male parents swam hyperactively in comparison to the control larvae. Contrasting trends in PFBS transfer and maternal factor transfer (e.g., proteins and lipids) to that of swimming behavior eliminated these two factors as major inducers of offspring developmental impairment. Inheritance of the exposed paternal methylome marks in offspring may be partially responsible for abnormal swimming behavior, although different toxic mechanisms may be involved depending on the exposure concentration. Overall, these findings suggest that inheritance of epigenetic modifications implicates a long-lasting threat of PFBS to the fitness and sustainability of fish populations.

Evaluate pure Breeding and Crossbreeding Strategy for Better Carcass and non-carcass Traits of Awassi, Chios, and their Reciprocal Crossbred Lambs

In Jordan, crossing local sheep with the exotic breed has an acceptable sound by farmers but needs scientific proof for planned-ahead crossing and introgression. This work aimed to find the best mating strategy on economic carcass and non-carcass traits of produced lambs under an intensive production system in Jordan. The mating strategy among Awassi and Chios for two years was designed to obtain different pure- and cross-bred lambs. They were pure Awassi, pure Chios, and reciprocal crosses of Awassi-Chios and Chios-Awassi lambs for two years. The studied factors included sex of lamb, breed, lamb birth type, age at slaughtering, and their two-way interactions. The lamb sex significantly affected (P &lt; 0.001) most carcass and non-carcass traits of economic importance. Similarly, the effect of age was notable (P &lt; 0.05) on all carcass and non-carcass traits. The breeds were significantly different (P &lt; 0.05) for the hot carcass, tail, and internal organs weights. Therefore, the use of Awassi sire as a paternal contributor for producing meat over one year in crossbreeding can be implemented for increasing carcass weights. The heterosis effect had only significant for tail weight. Significant differences for the liver with and without a trachea, kidney with and without fat, heart with and without fat, and lung between reciprocal crosses for heterosis percentages always favored the reciprocal cross of Awassi female parent. Interaction effects of age with sex were detected on body weight, carcass length, and kidney, while interaction effect of birth type with sex was significant for body weight and some internal organs. finally, significant interaction effects of the breed with both sex and birth type were significant for the cold carcass, tail, and some organs weights. In the present study, sheep producers might be benefited better if Awassi sire is used as a paternal contributor for producing meat over one year in crossbreeding strategy with Chios for increasing carcass weights.

GLP-1 neurons form a local synaptic circuit within the rodent nucleus of the solitary tract.

Glutamatergic neurons that express pre‐proglucagon (PPG) and are immunopositive (+) for glucagon‐like peptide‐1 (i.e., GLP‐1+ neurons) are located within the caudal nucleus of the solitary tract (cNTS) and medullary reticular formation in rats and mice. GLP‐1 neurons give rise to an extensive central network in which GLP‐1 receptor (GLP‐1R) signaling suppresses food intake, attenuates rewarding, increases avoidance, and stimulates stress responses, partly via GLP‐1R signaling within the cNTS. In mice, noradrenergic (A2) cNTS neurons express GLP‐1R, whereas PPG neurons do not. In this study, confocal microscopy in rats confirmed that prolactin‐releasing peptide (PrRP)+ A2 neurons are closely apposed by GLP‐1+ axonal varicosities. Surprisingly, GLP‐1+ appositions were also observed on dendrites of PPG/GLP‐1+ neurons in both species, and electron microscopy in rats revealed that GLP‐1+ boutons form asymmetric synaptic contacts with GLP‐1+ dendrites. However, RNAscope confirmed that rat GLP‐1 neurons do not express GLP‐1R mRNA. Similarly, Ca2+ imaging of somatic and dendritic responses in mouse ex vivo slices confirmed that PPG neurons do not respond directly to GLP‐1, and a mouse crossbreeding strategy revealed that <1% of PPG neurons co‐express GLP‐1R. Collectively, these data suggest that GLP‐1R signaling pathways modulate the activity of PrRP+ A2 neurons, and also reveal a local “feed‐forward” synaptic network among GLP‐1 neurons that apparently does not use GLP‐1R signaling. This local GLP‐1 network may instead use glutamatergic signaling to facilitate dynamic and potentially selective recruitment of GLP‐1 neural populations that shape behavioral and physiological responses to internal and external challenges.

Genetically reducing mTOR signaling rescues central insulin dysregulation in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease. The causes of sporadic AD, which represents more than 95% of AD cases, are unknown. Several AD risk factors have been identified and among these, type 2 diabetes increases the risk of developing AD by 2-fold. However, the mechanisms by which diabetes contributes to AD pathogenesis remain elusive. The mammalian target of rapamycin (mTOR) is a protein kinase that plays a crucial role in the insulin signaling pathway and has been linked to AD. We used a crossbreeding strategy to remove 1 copy of the mTOR gene from the forebrain of Tg2576 mice, a mouse model of AD. We used 20-month-old mice to assess changes in central insulin signaling and found that Tg2576 mice had impaired insulin signaling. These impairments were mTOR dependent as we found an improvement in central insulin signaling in mice with lower brain mTOR activity. Furthermore, removing 1 copy of mTOR from Tg2576 mice improved cognition and reduced levels of Aβ, tau, and cytokines. Our findings indicate that mTOR signaling is a key mediator of central insulin dysfunction in Tg2576. These data further highlight a possible role for mTOR signaling in AD pathogenesis and add to the body of evidence indicating that reducing mTOR activity could be a valid therapeutic approach for AD.

Impact of dendritic cells and adjuvant on the in vivo immunogenicity of HTLV-1 Tax 11-19 epitope in hybrid HLA-A2.1/DTR transgenic mice

Individually, HLA-A2.1 and CD11c-DTR transgenic mouse strains have been used to investigate the immunopathogenesis of different viruses and have provided important insights into current understanding of hostpathogen interactions during human T-cell leukemia virus type 1 (HTLV-1) infection. Here, these mice enabled the study of the CD8 T-cell immune response against a known MHC class I HLA-A2.1-restricted epitope 11-19 of the viral oncoprotein Tax delivered along with tetanus helper peptide without or with incomplete Freund’s adjuvant (IFA) in the absence and presence of dendritic cells (DCs). First, a cross breeding strategy was utilized to generate a HLA-A2.1/DTR hybrid strain that carries an HLA-A2.1 gene and diphtheria toxin receptor gene for in vivo depletion of CD11c DCs. Upon in vitro stimulation of splenocytes from immunized mice with autologous bone marrow-derived DCs primed with Tax11-19 antigen, DC-depleted mice showed marked attenuation in the proliferation of CD8 T-cells when compared with the non DC-depleted mice. Additionally, mice immunized with adjuvant demonstrated a much higher frequency of Tax11-19-specific cells response but overall reduced proliferation compared to the non-adjuvant group. A significantly high serum level of IL-6 coincided with depletion of DCs while a decrease in TGF-b cytokine associated with adjuvant use irrespective of DCs’ presence. In conclusion, these studies not only demonstrate that the clinically characterized Tax epitope 11-19 can be a potential candidate for the DC-based anti-HTLV-1 vaccine but also illustrate a broader application of the new HLA-A2.1/DTR-transgenic hybrid mouse strain as an important tool to investigate DC involvement in human class-I-restricted immune responses.

High-Throughput Sequencing and Mutagenesis to Accelerate the Domestication of Microlaena stipoides as a New Food Crop

Global food demand, climatic variability and reduced land availability are driving the need for domestication of new crop species. The accelerated domestication of a rice-like Australian dryland polyploid grass, Microlaena stipoides (Poaceae), was targeted using chemical mutagenesis in conjunction with high throughput sequencing of genes for key domestication traits. While M. stipoides has previously been identified as having potential as a new grain crop for human consumption, only a limited understanding of its genetic diversity and breeding system was available to aid the domestication process. Next generation sequencing of deeply-pooled target amplicons estimated allelic diversity of a selected base population at 14.3 SNP/Mb and identified novel, putatively mutation-induced polymorphisms at about 2.4 mutations/Mb. A 97% lethal dose (LD97) of ethyl methanesulfonate treatment was applied without inducing sterility in this polyploid species. Forward and reverse genetic screens identified beneficial alleles for the domestication trait, seed-shattering. Unique phenotypes observed in the M2 population suggest the potential for rapid accumulation of beneficial traits without recourse to a traditional cross-breeding strategy. This approach may be applicable to other wild species, unlocking their potential as new food, fibre and fuel crops.

Genetic control of the performance of maize hybrids using complex pedigrees and microsatellite markers

This study seeks to quantify the importance of epistatic effects on the heterosis of maize using complex pedigrees in a single model of the so-called bi-, tri-, and tetra-alleles in an analysis with and without information from microsatellite markers. To this end, 51 inbred lines were sampled from different backgrounds, obtaining 6 double cross hybrids, 14 triple cross hybrids, and 58 single cross hybrids, for a total of 78 hybrids. Seventy-nine microsatellite markers were used in the genotyping of the 51 lines. These markers were distributed throughout the 10 linkage groups in maize. This information was used to construct an information matrix on kinship. The mixed models and restricted maximum likelihood approaches were used to estimate additive, dominant and epistatic effects. It was observed that the dominant by dominant epistasis was the most important effect related to genetic control of the heterosis in maize. Also, our study demonstrated that it is possible to exploit a large amount of information when we jointly analyze simple, double, and three-way cross hybrids under the same model. Using this approach, it is possible to dissect heterosis into several components and to adopt the best crossbreeding strategy based on the importance of each component. Additionally, it was possible to verify that the use of molecular markers improves the accuracy of calculating the epistatic and dominance effects. Thus, using the current state-of-art in quantitative genetics and statistical methods the concept of crossbreeding can be expanded to frontiers that are far beyond the traditional general and specific combining ability.

Neuroprotective Function of Cellular Prion Protein in a Mouse Model of Amyotrophic Lateral Sclerosis

Transgenic mice expressing human mutated superoxide dismutase 1 (SOD1) linked to familial forms of amyotrophic lateral sclerosis are frequently used as a disease model. We used the SOD1G93A mouse in a cross-breeding strategy to study the function of physiological prion protein (Prp). SOD1G93APrp-/- mice exhibited a significantly reduced life span, and an earlier onset and accelerated progression of disease, as compared with SOD1G93APrp+/+ mice. Additionally, during disease progression, SOD1G93APrp-/- mice showed impaired rotarod performance, lower body weight, and reduced muscle strength. Histologically, SOD1G93APrp-/- mice showed reduced numbers of spinal cord motor neurons and extended areas occupied by large vacuoles early in the course of the disease. Analysis of spinal cord homogenates revealed no differences in SOD1 activity. Using an unbiased proteomic approach, a marked reduction of glial fibrillary acidic protein and enhanced levels of collapsing response mediator protein 2 and creatine kinase were detected in SOD1G93APrp-/- versus SOD1G93A mice. In the course of disease, Bcl-2 decreases, nuclear factor-kappaB increases, and Akt is activated, but these changes were largely unaffected by Prp expression. Exclusively in double-transgenic mice, we detected a significant increase in extracellular signal-regulated kinase 2 activation at clinical onset. We propose that Prp has a beneficial role in the SOD1G93A amyotrophic lateral sclerosis mouse model by influencing neuronal and/or glial factors involved in antioxidative defense, rather than anti-apoptotic signaling.

Increased systolic blood pressure and defective pressure‐natriuresis in mice lacking the insulin receptor in the thick ascending limb through collecting duct

Insulin affects sodium excretion and blood pressure. In order to examine the role of the insulin receptor (IR) in the kidney, we selectively knocked out the IR from the thick ascending limb (TAL) through collecting duct (CD) of the renal tubule by using a cre-recombinase/lox P cross-breeding strategy with Cre driven by Ksp-cadherin in mice. Immunoblotting revealed band density for the β-subunit of IR was reduced to 22% of the WT mean in the inner stripe of the outer medulla (OMH) of the KO mice. Baseline systolic blood pressures, measured by radiotelemetry, were significantly increased in the KO mice in the light period (mm Hg): 123 ± 3 (KO) versus 109 ± 5 (WT), but not different in the dark period. Moreover, OMH endothelial nitric oxide synthase protein abundance was significantly decreased in KO mice to 63% of the WT level. To examine pressure natriuresis, we administered, by gavage, 25 ml/kg/bw of 15% dextrose in 0.9% saline. Dextrose was included to raise endogenous insulin levels. Urine was collected every two hours after gavage. Blood pressure was monitored. The mean arterial blood pressure (MAP) was significantly increased, relative to baseline, in both KO and WT mice at 30 minutes. After 30 minutes, MAP came back to baseline in WT mice, however in KO mice it remained elevated significantly until 120 minutes. Furthermore, the urinary sodium excretion between 2 and 4 hours after gavage was significantly increased in WT, but not in KO mice. When dextrose was not included there were no differences between genotypes in blood pressure or sodium excretion. These data suggest a role for the IR in the renal TAL through CD in facilitating pressure natriuresis which may involve endothelial nitric oxide synthase.