Primordial germ cell proliferation is impaired in Fused Toes mutant embryos

Over the first 4 days of their life, primordial germ cells invade the endoderm, migrate into and through the developing hindgut, and traverse to the genital ridge where they cluster and ultimately inhabit the nascent gonad. Specific signal–receptor combinations between primordial germ cells and their immediate environment establish successful migration and colonization. Here we demonstrate that disruption of a cluster of six genes on murine chromosome 8, as exemplified by the Fused Toes (Ft) mutant mouse model, results in severely decreased numbers of primordial germ cells within the early gonad. Primordial germ cell migration appeared normal within Ft mutant embryos; however, germ cell counts progressively decreased during this time. Although no difference in apoptosis was detected, we report a critical decrease in primordial germ cell proliferation by E12.5. The six genes within the Ft locus include the IrxB cluster (Irx3, -5, -6), Fts, Ftm, and Fto, of which only Ftm, Fto, and Fts are expressed in primordial germ cells of the early gonad. From these studies, we have discovered that the Ft locus on mouse chromosome 8 is associated with cell cycle deficits within the primordial germ cell population that initiates just before translocation into the genital ridge.     

The domestication syndrome genes responsible for the major changes in plant form in the Triticeae crops

The process of crop domestication began 10,000 years ago in the transition of early humans from hunter/gatherers to pastoralists/farmers. Recent research has revealed the identity of some of the main genes responsible for domestication. Two of the major domestication events in barley were (i) the failure of the spike to disarticulate and (ii) the six-rowed spike. The former mutation increased grain yield by preventing grain loss after maturity, while the latter resulted in an up to 3-fold increase in yield potential. Here we provide an overview of the disarticulation systems and inflorescence characteristics, along with the genes underlying these traits, occurring in the Triticeae tribe.     

A twin-track approach has optimized proton and hydride transfer by dynamically coupled tunneling during the evolution of protochlorophyllide oxidoreductase

Protein dynamics are crucial for realizing the catalytic power of enzymes, but how enzymes have evolved to achieve catalysis is unknown. The light-activated enzyme protochlorophyllide oxidoreductase (POR) catalyzes sequential hydride and proton transfers in the photoexcited and ground states, respectively, and is an excellent system for relating the effects of motions to catalysis. Here, we have used the temperature dependence of isotope effects and solvent viscosity measurements to analyze the dynamics coupled to the hydride and proton transfer steps in three cyanobacterial PORs and a related plant enzyme. We have related the dynamic profiles of each enzyme to their evolutionary origin. Motions coupled to light-driven hydride transfer are conserved across all POR enzymes, but those linked to thermally activated proton transfer are variable. Cyanobacterial PORs require complex and solvent-coupled dynamic networks to optimize the proton donor-acceptor distance, but evolutionary pressures appear to have minimized such networks in plant PORs. POR from Gloeobacter violaceus has features of both the cyanobacterial and plant enzymes, suggesting that the dynamic properties have been optimized during the evolution of POR. We infer that the differing trajectories in optimizing a catalytic structure are related to the stringency of the chemistry catalyzed and define a functional adaptation in which active site chemistry is protected from the dynamic effects of distal mutations that might otherwise impact negatively on enzyme catalysis.     

Germ cell mutations of the ascidian Ciona intestinalis with TALE nucleases

Summary: Targeted mutagenesis of genes‐of‐interest, or gene‐knockout, is a powerful method to address the functions of genes. Engineered nucleases have enabled this approach in various organisms because of their ease of use. The ascidian Ciona intestinalis is an excellent organism to analyze gene functions by means of genetic technologies. In our previous study, we reported mutagenesis of Ciona somatic cells with TALE nucleases (TALENs) by electroporating expression constructs. In this study, we report germ cell mutagenesis of Ciona by microinjecting mRNAs encoding TALENs. TALEN mRNAs introduced mutations to target genes in both somatic and germ cells. TALEN‐mediated mutations in the germ cell genome were inherited by the next generation. We conclude that knockout lines of Ciona that have disrupted target genes can be established through TALEN‐mediated germ cell mutagenesis. genesis 52:431–439, 2014. © 2014 Wiley Periodicals, Inc.     

White Matter Microstructural Changes as Vulnerability Factors and Acquired Signs of Post-Earthquake Distress

Many survivors of severe disasters need psychological support, even those not suffering post-traumatic stress disorder (PTSD). The critical issue in understanding the psychological response after experiencing severe disasters is to distinguish neurological microstructural underpinnings as vulnerability factors from signs of emotional distress acquired soon after the stressful life event. We collected diffusion-tensor magnetic resonance imaging (DTI) data from a group of healthy adolescents before the Great East Japan Earthquake and re-examined the DTIs and anxiety levels of 30 non-PTSD subjects from this group 3–4 months after the earthquake using voxel-based analyses in a longitudinal DTI study before and after the earthquake. We found that the state anxiety level after the earthquake was negatively associated with fractional anisotropy (FA) in the right anterior cingulum (Cg) before the earthquake (r = −0.61, voxel level p<0.0025, cluster level p<0.05 corrected), and positively associated with increased FA changes from before to after the earthquake in the left anterior Cg (r = 0.70, voxel level p<0.0025, cluster level p<0.05 corrected) and uncinate fasciculus (Uf) (r = 0.65, voxel level p<0.0025, cluster level p<0.05 corrected). The results demonstrated that lower FA in the right anterior Cg was a vulnerability factor and increased FA in the left anterior Cg and Uf was an acquired sign of state anxiety after the earthquake. We postulate that subjects with dysfunctions in processing fear and anxiety before the disaster were likely to have higher anxiety levels requiring frequent emotional regulation after the disaster. These findings provide new evidence of psychophysiological responses at the neural network level soon after a stressful life event and might contribute to the development of effective methods to prevent PTSD.     

Suppressor of Cytokine Signaling 1 Counteracts Rhesus Macaque TRIM5α-Induced Inhibition of Human Immunodeficiency Virus Type-1 Production

Old world monkey TRIM5α is a host factor that restricts human immunodeficiency virus type-1 (HIV-1) infection. Previously, we reported that rhesus macaque TRIM5α (RhTRIM5α) restricts HIV-1 production by inducing degradation of precursor Gag. Since suppressor of cytokine signaling 1 (SOCS1) is known to enhance HIV-1 production by rescuing Gag from lysosomal degradation, we examined if SOCS1 is involved in RhTRIM5α-mediated late restriction. Over-expression of SOCS1 restored HIV-1 production in the presence of RhTRIM5α to a level comparable to that in the absence of RhTRIM5α in terms of titer and viral protein expression. Co-immunoprecipitation studies revealed that SOCS1 physically interacted with RhTRIM5α. Over-expression of SOCS1 affected RhTRIM5α expression in a dose-dependent manner, which was not reversed by proteasome inhibitors. In addition, SOCS1 and RhTRIM5α were detected in virus-like particles. These results suggest that SOCS1 alleviates RhTRIM5α-mediated regulation in the late phase of HIV-1 life cycle probably due to the destabilization of RhTRIM5α.     

Attractive and permissive activities of semaphorin 5A toward dorsal root ganglion axons in higher vertebrate embryos

Elongation of the efferent fibers of dorsal root ganglion (DRG) neurons toward their peripheral targets occurs during development. Attractive or permissive systems may be involved in this elongation. However, the molecular mechanisms that control it are largely unknown. Here we show that class 5 semaphorin Sema5A had attractive/permissive effects on DRG axons. In mouse embryos, Sema5A was expressed in and around the path of DRG efferent fibers, and cell aggregates secreting Sema5A attracted DRG axons in vitro. We also found that ectopic Sema5A expression in the spinal cord attracted DRG axons. Together, these findings suggest that Sema5A functions as an attractant to elongate DRG fibers and contributes to the formation of the early sensory network.     

A heparin-binding growth factor, midkine, binds to a chondroitin sulfate proteoglycan, PG-M/versican.

Midkine is a heparin-binding growth factor with survival-promoting and migration-enhancing activities. In order to understand the regulation of midkine signaling, we isolated midkine-binding proteoglycans from day 13 mouse embryos, when midkine is intensely expressed. Deglycosylation followed by SDS/PAGE revealed various protein bands; one of these was identified as PG-M/versican by in gel trypsin digestion and sequencing the resulting peptides. PG-M/versican isolated from day 13 mouse embryos bound midkine with a Kd of 1.0 nM. Pleiotrophin/heparin-binding growth-associated molecule, which has a structure related to midkine, was also bound similarly. Digestion with chondroitinase ABC, AC-I or B abolished the binding to midkine. Heparin as well as chondroitin sulfate D and E inhibited the binding. After chondroitinase ABC digestion, the midkine-binding PG-M/versican released 4-sulfated, 6-sulfated, 2, 6-disulfated and 4,6-disulfated unsaturated disaccharides. These results suggest that midkine binds to a polysulfated domain in the chondroitin sulfate chain with a region of dermatan sulfate structure. This proteoglycan may modulate the midkine activity, as binding to midkine can enhance midkine action by concentrating it to the cell periphery or inhibit the action by competing with the binding to a signaling receptor.     

Effect of tert-butyl hydroperoxide on cyclooxygenase and lipoxygenase metabolism of arachidonic acid in rabbit platelets

The effect of tert-butyl hydroperoxide (t-BOOH) on the formation of thromboxane (TX) B2, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) from exogenous arachidonic acid (AA) in washed rabbit platelets was examined. t-BOOH enhanced TXB2 and HHT formation at concentrations of 8 microM and below, and at 50 microM it inhibited the formation, suggesting that platelet cyclooxygenase activity can be enhanced or inhibited by t-BOOH depending on the concentration. t-BOOH inhibited 12-HETE production in a dose-dependent manner. When the platelets were incubated with 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid (12-HPETE) instead of AA, t-BOOH failed to inhibit the conversion of 12-HPETE to 12-HETE, indicating that the inhibition of 12-HETE formation by t-BOOH occurs at the lipoxygenase step. Studies utilizing indomethacin (a selective cyclooxygenase inhibitor) and desferrioxamine (an iron-chelating agent) revealed that the inhibitory effect of t-BOOH on the lipoxygenase is not mediated through the activation of the cyclooxygenase and that this effect of t-BOOH is due to the hydroperoxy moiety. These results suggest that hydroperoxides play an important role in the control of platelet cyclooxygenase and lipoxygenase activities.     

Resequencing the<Emphasis Type="Italic">Vrs1</Emphasis> gene in Spanish barley landraces revealed reversion of six-rowed to two-rowed spike

Six-rowed spike 1 (Vrs1) is a gene of major importance for barley breeding and germplasm management as it is the main gene determining spike row-type (2-rowed vs. 6-rowed). This is a widely used DUS trait, and has been often associated to phenotypic traits beyond spike type. Comprehensive re-sequencing Vrs1 revealed three two-rowed alleles (Vrs1.b2; Vrs1.b3; Vrs1.t1) and four six-rowed (vrs1.a1; vrs1.a2; vrs1.a3; vrs1.a4) in the natural population. However, the current knowledge about Vrs1 alleles and its distribution among Spanish barley subpopulations is still underexploited. We analyzed the gene in a panel of 215 genotypes, made of Spanish landraces and European cultivars. Among 143 six-rowed accessions, 57 had the vrs1.a1 allele, 83 were vrs1.a2, and three showed the vrs1.a3 allele. Vrs1.b3 was found in most two-rowed accessions, and a new allele was observed in 7 out of 50 two-rowed Spanish landraces. This allele, named Vrs1.b5, contains a ‘T’ insertion in exon 2, originally proposed as the causal mutation giving rise to the six-row vrs1.a2 allele, but has an additional upstream deletion that results in the change of 15 amino acids and a potentially functional protein. We conclude that eight Vrs1 alleles (Vrs1.b2, Vrs1.b3, Vrs1.b5, Vrs1.t1, vrs1.a1, vrs1.a2, vrs1.a3, vrs1.a4) discriminate two and six-rowed barleys. The markers described will be useful for DUS identification, plant breeders, and other crop scientists.