New isozyme systems for maize (Zea mays L.): Aconitate hydratase,adenylate kinase,NADH dehydrogenase,and shikimate dehydrogenase

Electrophoretic variation and inheritance of four novel enzyme systems were studied in maize (Zea mays L.). A minimum of 10 genetic loci collectively encodes isozymes of aconitate hydratase (ACO; EC 4.2.1.3.), adenylate kinase (ADK; EC 2.7.4.3), NADH dehydrogenase (DIA; EC 1.6.99.—), and shikimate dehydrogenase (SAD; EC 1.1.1.25). At least four loci are responsible for the genetic control of ACO. Genetic data for two of the encoding loci,Aco1 andAco4, demonstrated that at least two maize ACOs are active as monomers. Analysis of organellar preparations suggests that ACO1 and ACO4 are localized in the cytosolic and mitochondrial subcellular fractions, respectively. Maize ADK is encoded by a single nuclear locus,Adk1, governing monomeric enzymes that are located in the chloroplasts. Two cytosolic and two mitochondrial forms of DIA were electrophoretically resolved. Segregation analyses demonstrated that the two cytosolic isozymes are controlled by separate loci,Dia1 andDia2, coding for products that are functional as monomers (DIA1) and dimers (DIA2). The major isozyme of SAD is apparently cytosolic, although an additional faintly staining plastid form may be present. Alleles atSad1 are each associated with two bands that cosegregate in controlled crosses. Linkage analyses and crosses with B-A translocation stocks were effective in determining the map locations of six loci, including the previously described but unmapped locusAcp4. Several of these loci were localized to sparsely mapped regions of the genome.Dia2 andAcp4 were placed on the distal portion of the long arm of chromosome 1, 12.6 map units apart.Dia1 was localized to chromosome 2, 22.2 centimorgans (cM) fromB1. Aco1 was mapped to chromosome 4, 6.2 cM fromsu1. Adk1 was placed on the poorly marked short arm of chromosome 6, 8.1 map units fromrgd1. Less than 1% recombination was observed betweenGlu1 (on chromosome 10) andSad1. In contrast to many other maize isozyme systems, there was little evidence of gene duplication or of parallel linkage relationships for these allozyme loci. This work was supported by grants from Pioneer Hi-Bred International, Inc., of Johnston, Iowa, the National Institute of Health (Research Grant GM11546), and the United States Department of Agriculture (Competitive Research Grant 83-CRCR-1-1273). This is Paper No. 11372 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh.     

Short‐term response of a declining woodland bird assemblage to the removal of a despotic competitor

Interspecific aggression by the noisy miner (Manorina melanocephala), a highly despotic species, is homogenizing woodland avifaunas across eastern Australia. Although a native species, the noisy miner's aggressive exclusion of small birds is a Key Threatening Process under national law. Large‐scale removal of noisy miners has been proposed as a management response to this threat following increases in miner presence due to anthropogenic land use practices. We tested this proposal by experimentally removing noisy miners from eucalypt woodland remnants (16–49 ha), assigned randomly as control (n = 12) or treatment (miner removal) sites (n = 12). Standardized bird surveys were conducted before and after removal, and generalized linear mixed models were used to investigate the effect of miner removal on bird assemblage metrics. Despite removing 3552 noisy miners in three sessions of systematic shooting, densities of noisy miners remained similarly high in treatment and control sites, even just 14 days after their removal. However, there was evidence of an increase in richness and abundance of small birds in treatment sites compared to controls—an effect we only expected to see if noisy miner densities were drastically reduced. We suggest that miner removal may have reduced the ability of the recolonizing miners to aggressively exclude small birds, even without substantially reducing miner densities, due to the breakdown of social structures that are central to the species' despotic behaviour. However, this effect on small birds is unlikely to persist in the long term. Synthesis and applications: Despite evidence from other studies that direct removal of noisy miners can result in rapid and sustained conservation benefit for bird communities at small scales, our findings cast doubt on the potential to scale‐up this management approach. The circumstances under which direct control of noisy miners can be achieved remain unresolved.     

Patterns of isozyme variation between maize and Mexican annual teosinte

Isozyme variation in 94 accessions of Mexican maize (Zea mays ssp. mays) and 37 collections of Mexican annual teosinte (Z. mays ssp. mexicana and var. parviglumis) are compared. Variety parviglumis (a predominantly wild plant) shows a closer genetic relationship to maize than does ssp. mexicana (a weedy teosinte often found in maize fields). The isozyme data suggest that maize and Z. mays var. parviglumis share a more recent common ancestor than either of these taxa share with other members of the genus Zea. In this sense, the isozyme data support the theory that maize is a domesticated form of teosinte. Isozyme data provide no evidence for independent origin of Mexican maize races from different taxa of teosinte. Isozyme analysis suggests that gene flow between maize and ssp. mexicana exists, but that it is highly restricted and more probably goes from weed into crop. Maize and var. parviglumis are isozymically too similar and too variable to allow patterns of gene flow between them (if any) to be discerned. The maize- teosinte complex does not fit a model applied to some other crops in that (I) weedy teosinte (ssp. mexicana) does not appear to be a hybrid of the wild form (var. parviglumis,) and maize and (2) the weedy form does not act as a genetic bridge between wild form and crop.     

Biological aging as a diffusion phenomenon

The general cross-linkage theory of biological aging is pointed out to consist of two distinct branches: mutation theory and diffusion theory. Only diffusion theory is considered though. The diffusion theory of aging is expressed as a sum of terms. One of those terms is expressed in differential equation form, and the complete mathematical solution to it obtained under certain limiting assumptions. An approximation to the complete solution is applied to four distinct cases—(1) rat tendon collagen, (2) cellular waste products in humans, (3) collagen in humans and (4) lipofuscins in the human myocardium. Only cases (1) and (4) are compared to experimental data. Case (1) shows excellent agreement, while case (4) displays discrepancies which suggest that the lipofuscins have an age pigment precursor.     

Interaction of a nuclear factor-1-like protein with the regulatory region of the human polyomavirus JC virus

We have initiated a study to identify host proteins which interact with the regulatory region of the human polyomavirus JC (JCV), which is associated with the demyelinating disease, progressive multifocal leukoencephalopathy. We examined the interaction of nuclear proteins prepared from different cell lines with the JCV regulatory region by DNA binding gel retardation assays. Binding was detected with nuclear extracts prepared from human fetal glial cells, glioma cells, and HeLa cells. Little or no binding was detected with nuclear extracts prepared from human embryonic kidney cells. Competitive binding assays suggest that the nuclear factor(s) which interacted with the JCV regulatory region was different from those which interacted with the regulatory region of the closely related polyomavirus SV40. We found three areas in the JCV regulatory region protected from DNase I digestion: site A, located just upstream from the TATA sequence in the first 98-base pair (bp) repeat; site B, located upstream from the TATA sequence in the second 98-bp repeat; and site C, located just following the second 98-bp repeat. There were some differences in the ability of the nuclear factor(s) from the two brain cell lines and HeLa cells to completely protect the nucleotides within the footprint region. The results from the DNase I protective studies and competitive DNA binding studies with specific oligonucleotides, suggest that nuclear factor-1 or a nuclear factor-1-like factor is interacting with all three sites in the JCV regulatory region. In addition, the results suggest that the nuclear factor which interacts with the JCV regulatory region from human brain cell lines is different from the factor found in HeLa cells.     

Protein proximity networks and functional evaluation of the casein kinase 1 gamma family reveal unique roles for CK1γ3 in WNT signaling

Aberrant activation or suppression of WNT/β-catenin signaling contributes to cancer initiation and progression, neurodegeneration, and bone disease. However, despite great need and more than 40 years of research, targeted therapies for the WNT pathway have yet to be fully realized. Kinases are considered exceptionally druggable and occupy key nodes within the WNT signaling network, but several pathway-relevant kinases remain understudied and “dark.” Here, we studied the function of the casein kinase 1γ (CSNK1γ) subfamily of human kinases and their roles in WNT signaling. miniTurbo-based proximity biotinylation and mass spectrometry analysis of CSNK1γ1, CSNK1γ2, and CSNK1γ3 revealed numerous components of the β-catenin–dependent and β-catenin–independent WNT pathways. In gain-of-function experiments, we found that CSNK1γ3 but not CSNK1γ1 or CSNK1γ2 activated β-catenin–dependent WNT signaling, with minimal effect on other signaling pathways. We also show that within the family, CSNK1γ3 expression uniquely induced low-density lipoprotein receptor–related protein 6 phosphorylation, which mediates downstream WNT signaling transduction. Conversely, siRNA-mediated silencing of CSNK1γ3 alone had no impact on WNT signaling, though cosilencing of all three family members decreased WNT pathway activity. Finally, we characterized two moderately selective and potent small-molecule inhibitors of the CSNK1γ family. We show that these inhibitors and a CSNK1γ3 kinase–dead mutant suppressed but did not eliminate WNT-driven low-density lipoprotein receptor–related protein 6 phosphorylation and β-catenin stabilization. Our data suggest that while CSNK1γ3 expression uniquely drives pathway activity, potential functional redundancy within the family necessitates loss of all three family members to suppress the WNT signaling pathway.     

CyberKnife versus multicatheter interstitial brachytherapy for accelerated partial breast irradiation: a dosimetrical assessment with focus on organs at risk

BackgroundThe purpose of the study was to dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and stereotactic radiotherapy with CyberKnife (CK) for accelerated partial breast irradiation with special focus on dose to organs at risk (OARs).Materials and methodsTreatment plans of thirty-one patients treated with MIBT were selected and additional CK plans were created on the same CT images. The OARs included ipsilateral non-target and contralateral breast, ipsilateral and contralateral lung, skin, ribs, and heart for left sided cases. The fractionation was identical (4 × 6.25 Gy). Dose-volume parameters were calculated for both techniques and compared.ResultsThe D90 of the PTV for MIBT and CK were similar (102.4% vs. 103.6%, p = 0.0654), but in COIN the MIBT achieved lower value (0.75 vs. 0.91, p < 0.001). Regarding the V100 parameter of non-target breast CK performed slightly better than MIBT (V100: 1.1% vs. 1.6%), but for V90, V50 and V25 MIBT resulted in less dose. Every examined parameter of ipsilateral lung, skin, ribs and contralateral lung was significantly smaller for MIBT than for CK. Protection of the heart was slightly better with MIBT, but only the difference of D2cm³ was statistically significant (17.3% vs. 20.4%, p = 0.0311). There were no significant differences among the dose-volume parameters of the contralateral breast.ConclusionThe target volume can be properly irradiated by both techniques with high conformity and similar dose to the OARs. MIBT provides more advantageous plans than CK, except for dose conformity and the dosimetry of the heart and contralateral breast. More studies are needed to analyze whether these dosimetrical findings have clinical significance.