Why are second-generation transgenic crops not yet available in the market?

Recent studies predict that global food demand of major grain crops will not be accompanied by the required increase in yield (Hall and Richards, 2013). Additionally, current figures estimate that the impact of climate change on agriculture will yield losses of 8-43%, mainly due to abiotic stresses. A second generation of transgenic crops (SGTC) was projected to mitigate these constraints worldwide. However, SGTC remain unavailable as market products. Here, we present our viewpoints about current limitations and future perspectives.

MYH7-related myopathies: clinical, histopathological and imaging findings in a cohort of Italian patients.

BACKGROUND: Myosin heavy chain 7 (MYH7)-related myopathies are emerging as an important group of muscle diseases of childhood and adulthood, with variable clinical and histopathological expression depending on the type and location of the mutation. Mutations in the head and neck domains are a well-established cause of hypertrophic cardiomyopathy whereas mutation in the distal regions have been associated with a range of skeletal myopathies with or without cardiac involvement, including Laing distal myopathy and Myosin storage myopathy. Recently the spectrum of clinical phenotypes associated with mutations in MYH7 has increased, blurring this scheme and adding further phenotypes to the list. A broader disease spectrum could lead to misdiagnosis of different congenital myopathies, neurogenic atrophy and other neuromuscular conditions. RESULTS: As a result of a multicenter Italian study we collected clinical, histopathological and imaging data from a population of 21 cases from 15 families, carrying reported or novel mutations in MYH7. Patients displayed a variable phenotype including atypical pictures, as dropped head and bent spine, which cannot be classified in previously described groups. Half of the patients showed congenital or early infantile weakness with predominant distal weakness. Conversely, patients with later onset present prevalent proximal weakness. Seven patients were also affected by cardiomyopathy mostly in the form of non-compacted left ventricle. Muscle biopsy was consistent with minicores myopathy in numerous cases. Muscle MRI was meaningful in delineating a shared pattern of selective involvement of tibialis anterior muscles, with relative sparing of quadriceps. CONCLUSION: This work adds to the genotype-phenotype correlation of MYH7-relatedmyopathies confirming the complexity of the disorder.

WES in a family trio suggests involvement of TECPR2 in a complex form of progressive motor neuron disease.

We have performed whole-exome sequencing in a family trio with a 16-year-old girl suffering of progressive motor neuron disease. There was no family history of the disease and no parental consanguinity. Our exome analysis indicated the proband as a compound heterozygote for two missense variants in the TECPR2 gene according to a recessive mode of inheritance. The TECPR2 gene has been reported as a positive regulator of autophagy which is an essential mechanism for maintaining neuron homeostasis and survival and plays a key role in major adult and pediatric neurodegenerative diseases. Variants in this gene have been found responsible for a recently described form of hereditary spastic paraplegia called SPG49 in two previous reports. We propose that both variants causing amino acid substitution, p.Leu684Val and p.Thr903Met, inherited in trans-phase compound heterozygote form, can be responsible for the phenotype observed in our patient. We also consider the possible contribution of a heterozygous variant in the SPG7 gene. Sanger sequencing confirmed the segregation of variants within the family tree including the patient's unaffected brother.

Fertility, segregation at a herbicide-resistance locus, and genome structure in BC hybrids from two important weedy Amaranthus species.

Field studies have established high potential for hybridization between two important and often coexisting weedy species, Amaranthus hybridus and Amaranthus tuberculatus. Prezygotic reproductive barriers between these species are believed to be limited to pollen competition and availability. A greenhouse study showed that a herbicide-resistance gene (ALS) from A. hybridus could be introgressed into an advanced A. tuberculatus background (BC2). However, evidence is lacking in support of such transfer in nature. Postzygotic reproductive barriers may minimize, if not preclude, natural introgression. Indeed, A. hybridus xA. tuberculatus hybrids are characterized by reduced fertility and even floral neuterism. The purpose of this study was to assess hybrid fertility in the BC1 generation and its relationship with genome structure and segregation at ALS. Fertility was assessed by measuring seed output and by pollen evaluation, and segregation at ALS was determined via a molecular marker system. The two parental species have the same ploidy (2n = 32) but differ in DNA content (2C) values, with A. tuberculatus chromosomes being on average 29% greater than those of A. hybridus. Given that most (98%) BC(1)s were homoploid, 2C values were used as indicators of relative genomic constitution. Fertility in the BC1 generation was greater than that of F1s, and 3% of BC1s had seed output similar to that of the parental species. Fertility in the BC1 did not correlate (in a strict way) with reconstitution of parental genomes. Hybrid sterility appeared to be controlled by relatively few loci. Heterozygosity at ALS was negatively correlated with fertility. Also, the A. tuberculatus ALS allele was not observed in the A. hybridus sexual condition, monoecism. Linkage of ALS to a locus associated (directly or via epistasis) with hybrid sterility may explain the fertility penalty observed with ALS introgression. Moreover, this linkage might explain why sequenced herbicide-resistance ALS alleles from sympatric A. tuberculatus and A. hybridus populations show independent evolution.

Amaranthus hybridus can be pollinated frequently by A. tuberculatus under field conditions.

Recent studies have confirmed that weedy Amaranthus species are capable of interspecific hybridization, and such hybridization may foster the evolution of herbicide resistance. However, the extent to which hybridization among these species occurs in nature is unknown. The purpose of this study was to determine the frequency under field conditions at which A. hybridus, a monoecious and predominantly self-pollinated species, would be pollinated by A. tuberculatus, a dioecious species. To do this, parents carrying different alleles at the ALS locus, which encodes a herbicide target site, were used. Male A. tuberculatus parents were homozygous for a dominant herbicide-insensitive allele, while A. hybridus parents were homozygous for a sensitive form. Hybrid progeny therefore could be detected via herbicide selection. Mean hybridization frequencies between 0.4 and 2.3% were obtained, depending on the proximity between parents (P=0.02). The robustness of the hybrid selection assay was verified using a molecular marker and DNA content analyses. Using these techniques, more than 99% of the progeny that survived the herbicide were confirmed to be hybrids. Frequencies obtained in this study were many times higher than the generally expected rate of mutation. Therefore, even minimal fertility in hybrid progeny would support the view that hybridization could play a role in adaptive evolution of weedy Amaranthus species.

Platelet cNOS activity is reduced in patients with IDDM and NIDDM.

Several studies in vitro and in vivo suggest that the nitric oxide (NO) production is impaired in diabetes mellitus. Reduced levels of NO could contribute to vascular alteration facilitating platelet-vascular wall interaction, adhesion of monocytes to endothelium, vascular smooth muscle proliferation and by decreasing endothelium-dependent vasodilation. In this study we evaluated the activity of the constitutive nitric oxide synthase (cNOS) in platelets of patients with insulin-dependent diabetes mellitus (IDDM) and with non-insulin-dependent diabetes mellitus (NIDDM). When compared to that of normal subjects, cNOS activity is significantly lower in patients with IDDM and with NIDDM (1.57 +/- 0.25 vs. 0.66 +/- 0.10 fmol/min/10(9) PLTs and 1.57 +/- 0.25 vs. 0.67 +/- 0.08, respectively; p<0.005). These data demonstrate that the platelet cNOS activity is decreased in diabetes mellitus.

Middle T antigen-transformed endothelial cells exhibit an increased activity of nitric oxide synthase.

Endothelioma cell lines transformed by polyoma virus middle T antigen (mTa) cause cavernous hemangiomas in syngeneic mice by recruitment of host cells. The production of nitric oxide (NO), as measured by nitrite and citrulline production, was significantly higher in mTa-transformed endothelial cells in comparison with nontransformed control cells. The maximal activity of NO synthase (NOS) was about 200-fold higher in cell lysates from the tEnd.1 endothelioma cell line than in lysates from nontransformed controls, whereas the affinity for arginine did not differ. The biochemical characterization of NOS and the study of mRNA transcripts indicate that tEnd.1 cells express both the inducible and the constitutive isoforms. NOS hyperactivity is not a simple consequence of cell transformation but needs a tissue-specific mTa expression. Since tEnd.1-conditioned medium induces NOS activity in normal endothelial cells, most likely NOS hyperactivity in endothelioma cells is attributable to the release of a soluble factor. This NOS-activating factor, which seems to be an anionic protein, could stimulate tEnd.1 cells to express NOS by an autocrine way. By the same mechanism, tEnd.1 cells could induce NOS in the neighboring endothelial cells, and NO release could play a role in the hemangioma development. Such hypothesis is confirmed by our in vivo experiments, showing that the administration of the NOS inhibitor L-canavanine to endothelioma-bearing mice significantly reduced both the volume and the relapse time of the tumor.