Reverse breeding: a novel breeding approach based on engineered meiosis

Reverse breeding (RB) is a novel plant breeding technique designed to directly produce parental lines for any heterozygous plant, one of the most sought after goals in plant breeding. RB generates perfectly complementing homozygous parental lines through engineered meiosis. The method is based on reducing genetic recombination in the selected heterozygote by eliminating meiotic crossing over. Male or female spores obtained from such plants contain combinations of non-recombinant parental chromosomes which can be cultured in vitro to generate homozygous doubled haploid plants (DHs). From these DHs, complementary parents can be selected and used to reconstitute the heterozygote in perpetuity . Since the fixation of unknown heterozygous genotypes is impossible in traditional plant breeding, RB could fundamentally change future plant breeding. In this review, we discuss various other applications of RB, including breeding per chromosome.     

Biological Comparison of Two Genotypes of Helicoverpa armigera Single-Nucleocapsid Nucleopolyhedrovirus

Baculovirus isolates from the same host species often show a considerable degree of variation on phenotypes. The completely sequenced genotypes C1 and G4 of Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HaSNPV) were compared. Bioassay studies suggested that nearly double of HaSNPV G4 virus was required compared with HaSNPV C1 to achieve a similar LD₅₀, and at the LD₉₀ level the insect-killing speed for HaSNPV C1 was quicker than that of HaSNPV G4. The budded virus (BV) production of HaSNPV C1 was nearly two- to threefold higher at 24 and 48 h post-infection (p.i.) than that of HaSNPV G4. However, the kinetics of polyhedral inclusion body (PIB) formation in HzAM1 cells was similar in both the genotypes, which implied that the insect-killing speed was not influenced by PIB formation, but by the kinetics of BV production. The results suggested that the HaSNPV C1 isolate was a better choice than HaSNPV G4 virus for controlling H. armigera.     

An Ancestral Deuterostome Family of Two-pore Channels Mediates Nicotinic Acid Adenine Dinucleotide Phosphate-dependent Calcium Release from Acidic Organelles

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent and widespread calcium-mobilizing messenger, the properties of which have been most extensively described in sea urchin eggs. The molecular basis for calcium release by NAADP, however, is not clear and subject to controversy. Recent studies have provided evidence that members of the two-pore channel (TPC) family in mammals are the long sought after target channels for NAADP. Here, we show that the TPC3 gene, which has yet to be functionally characterized, is present throughout the deuterostome lineage but is a pseudogene in humans and other primates. We report the molecular cloning of the complete ancestral TPC gene family from the sea urchin and demonstrate that all three isoforms localize to acidic organelles to mediate NAADP-dependent calcium release. Our data highlight the functional divergence of this novel gene family during deuterostome evolution and provide further evidence that NAADP mediates calcium release from acidic stores through activation of TPCs.     

Genetic polymorphisms of DNA repair gene XRCC1 and risk of uterine leiomyoma

The objective was to study the relationship between the polymorphisms of the DNA repair gene XRCC1 Arg399Gln, Arg194Trp, and Arg280His uterine leiomyoma in a Chinese population. In the case–control study, we compared the XRCC1 gene polymorphism of 136 uterine leiomyoma patients and 140 healthy controls by using the polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The results suggested that the genotype Arg/Arg of codon 280 was significantly different from its heterozygote (odds ratio [OR] = 3.633, 95% confidence interval [CI]: 2.147–6.148). In conclusion, the results suggest that polymorphism of XRCC1 Arg280His was associated with the increased risk of uterine leiomyoma in a Chinese population.     

甜高粱填充甘蔗榨期生产燃料乙醇的可行性

为了探讨在甘蔗产区种植甜高粱填充甘蔗压榨期,利用现有压榨设备生产燃料乙醇的可行性,2008年选用15个早、中、晚熟甜高粱品种在广西柳州进行了分期播种试验,从3月到9月,共播种7次,研究不同播期对茎秆产量、籽粒产量、茎秆糖锤度、叶片产量等的影响。研究表明,3～8月播种,所有参试品种均能正常生长,9月底播种,所有品种均不能正常成熟。茎秆鲜产最高的品种是Sart和PT3-S,平均单季茎秆产量分别为79.28 t/hm2和78.58 t/hm2,双季茎秆鲜产分别为157.95 t/hm2和155.25 t/hm2。从6月底开始,早熟品种开始成熟,之后,不同品种陆续成熟,一直到12月底,均有品种可以收获。年度双季乙醇产量最高产量可达9.14 t/hm2。此外,还估算了木质纤维素产量,讨论了甘蔗区发展甜高粱填充甘蔗空榨期生产燃料乙醇的可行性以及甜高粱综合利用的潜力。     

Nepetin inhibits osteoclastogenesis by inhibiting RANKL‐induced activation of NF‐κB and MAPK signalling pathway,and autophagy

Aseptic prosthetic loosening due to wear particle–induced inflammatory osteolysis is the main cause of failure for artificial joint replacement. The inflammatory response and the production of pro‐osteoclastic factors lead to elevation of osteoclast formation and excessive activity results in extensive bone destruction around the bone‐implant interface. Here we showed that Nepetin, a natural bioactive flavonoid with proven anti‐inflammatory and anti‐proliferative properties, potently inhibited RANKL‐induced osteoclast differentiation, formation and bone resorption in vitro, and protected mice against the deleterious effects of titanium particle–induced calvarial osteolysis in vivo. Mechanistically, Nepetin attenuated RANKL‐induced activation of NF‐κB and MAPK signalling pathways and TRAF6‐dependent ubiquitination of Beclin 1 which is necessary for the induction of autophagy. In brief, our study demonstrates the potential therapeutic application of Nepetin against osteoclast‐mediated osteolytic diseases.     

Ankyrin-G Participates in INa Remodeling in Myocytes from the Border Zones of Infarcted Canine Heart

Cardiac Na channel remodeling provides a critical substrate for generation of reentrant arrhythmias in border zones of the infarcted canine heart. Recent studies show that Na_v1.5 assembly and function are linked to ankyrin-G, gap, and mechanical junction proteins. In this study our objective is to expound the status of the cardiac Na channel, its interacting protein ankyrinG and the mechanical and gap junction proteins at two different times post infarction when arrhythmias are known to occur; that is, 48 hr and 5 day post coronary occlusion. Previous studies have shown the origins of arrhythmic events come from the subendocardial Purkinje and epicardial border zone. Our Purkinje cell (Pcell) voltage clamp study shows that I_Na and its kinetic parameters do not differ between Pcells from the subendocardium of the 48hr infarcted heart (IZPCs) and control non-infarcted Pcells (NZPCs). Immunostaining studies revealed that disturbances of Na_v1.5 protein location with ankyrin-G are modest in 48 hr IZPCs. Therefore, Na current remodeling does not contribute to the abnormal conduction in the subendocardial border zone 48 hr post myocardial infarction as previously defined. In addition, immunohistochemical data show that Cx40/Cx43 co-localize at the intercalated disc (IDs) of control NZPCs but separate in IZPCs. At the same time, Purkinje cell desmoplakin and desmoglein2 immunostaining become diffuse while plakophilin2 and plakoglobin increase in abundance at IDs. In the epicardial border zone 5 days post myocardial infarction, immunoblot and immunocytochemical analyses showed that ankyrin-G protein expression is increased and re-localized to submembrane cell regions at a time when Na_v1.5 function is decreased. Thus, Na_v1.5 and ankyrin-G remodeling occur later after myocardial infarction compared to that of gap and mechanical junctional proteins. Gap and mechanical junctional proteins remodel in IZPCs early, perhaps to help maintain Na_v1.5 subcellular location position and preserve its function soon after myocardial infarction.     

pRb is an obesity suppressor in hypothalamus and high‐fat diet inhibits pRb in this location

pRb is frequently inactivated in tumours by mutations or phosphorylation. Here, we investigated whether pRb plays a role in obesity. The Arcuate nucleus (ARC) in hypothalamus contains antagonizing POMC and AGRP/NPY neurons for negative and positive energy balance, respectively. Various aspects of ARC neurons are affected in high‐fat diet (HFD)‐induced obesity mouse model. Using this model, we show that HFD, as well as pharmacological activation of AMPK, induces pRb phosphorylation and E2F target gene de‐repression in ARC neurons. Some affected neurons express POMC; and deleting Rb1 in POMC neurons induces E2F target gene de‐repression, cell‐cycle re‐entry, apoptosis, and a hyperphagia‐obesity‐diabetes syndrome. These defects can be corrected by combined deletion of E2f1. In contrast, deleting Rb1 in the antagonizing AGRP/NPY neurons shows no effects. Thus, pRb‐E2F1 is an obesity suppression mechanism in ARC POMC neurons and HFD‐AMPK inhibits this mechanism by phosphorylating pRb in this location.