Identifying Plectin Isoform Functions through Animal Models

Plectin, a high-molecular-weight cytoskeletal linker protein, binds with high affinity to intermediate filaments of all types and connects them to junctional complexes, organelles, and inner membrane systems. In addition, it interacts with actomyosin structures and microtubules. As a multifunctional protein, plectin has been implicated in several multisystemic diseases, the most common of which is epidermolysis bullosa simplex with muscular dystrophy (EBS-MD). A great part of our knowledge about plectin’s functional diversity has been gained through the analysis of a unique collection of transgenic mice that includes a full (null) knockout (KO), several tissue-restricted and isoform-specific KOs, three double KOs, and two knock-in lines. The key molecular features and pathological phenotypes of these mice will be discussed in this review. In summary, the analysis of the different genetic models indicated that a functional plectin is required for the proper function of striated and simple epithelia, cardiac and skeletal muscle, the neuromuscular junction, and the vascular endothelium, recapitulating the symptoms of humans carrying plectin mutations. The plectin-null line showed severe skin and muscle phenotypes reflecting the importance of plectin for hemidesmosome and sarcomere integrity; whereas the ablation of individual isoforms caused a specific phenotype in myofibers, basal keratinocytes, or neurons. Tissue-restricted ablation of plectin rendered the targeted cells less resilient to mechanical stress. Studies based on animal models other than the mouse, such as zebrafish and C. elegans, will be discussed as well.

Generation of a new six1-null line in Xenopus tropicalis for study of development and congenital disease

The vertebrate Six (Sine oculis homeobox) family of homeodomain transcription factors play critical roles in the development of several organs. Six1 plays a central role in cranial placode development, including the precursor tissues of the inner ear, as well as other cranial sensory organs and the kidney. In humans, mutations in SIX1 underlie some cases of branchio-oto-renal syndrome (BOR), which is characterized by moderate to severe hearing loss. We utilized CRISPR/Cas9 technology to establish a six1 mutant line in Xenopus tropicalis that is available to the research community. We demonstrate that at larval stages, the six1-null animals show severe disruptions in gene expression of putative Six1 target genes in the otic vesicle, cranial ganglia, branchial arch and neural tube. At tadpole stages, six1-null animals display dysmorphic Meckel's, ceratohyal and otic capsule cartilage morphology. This mutant line will be of value for the study of the development of several organs as well as congenital syndromes that involve these tissues.

Identification and molecular characterization of mutant line deficiency in three waxy proteins of common wheat (Triticum aestivum L.)

Starch is the main component of wheat (Triticum aestivum L.) grain and a key factor in determining wheat processing quality. The Wx gene is the gene responsible for amylose synthesis. An ethyl methanesulfonate (EMS) mutagenized population was generated using common wheat cv. Gao 8901, a popular and high-quality cultivar in China. A waxy mutant (Wx-null) was isolated by screening M3 seeds with KI-I2 staining of endosperm starch. No obvious waxy proteins in Wx-null line were detected using Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). DNA sequencing revealed three SNPs and a 3-bp InDel in the first exon, and a 16-bp InDel at the junction region of the first Wx-A1 intron from the Wx-null line. Six SNPs were identified in Wx-B1 gene of Wx-null line compared to the wild-type Gao 8901, including four missense mutations. One nonsense mutation was found at position 857 in the fourth exon, which resulted in a premature stop codon. Expression levels of Wx genes were dramatically reduced in the Wx-null line. There were no detectable differences in granule size and morphology between Wx-null and wild-type, but the Wx-null line contained more B-type starch granules. The amylose content of the Wx-null line (0.22%) was remarkably lower compared to the wild-type Gao 8901 (24.71%). Total starch is also lower in the Wx-null line. The Wx-null line may provide a potential waxy material with high agronomic performance in wheat breeding programs.

Identification and molecular characterization of mutant line deficiency in three waxy proteins of common wheat (Triticum aestivum L.)

Background: Starch is the main component of wheat (Triticum aestivum L.) grain and a key factor in determining wheat processing quality. The Wx gene encodes the granule bound starch synthase I (GBSS I) and is the sole gene responsible for amylose synthesis. Results: A waxy mutant (Wx-null) was isolated by screening M3 seeds derived from 1.0% EMS mutagenized materials with I2-KI staining of endosperm starch. SDS-PAGE electrophoresis confirmed that the Wx-null line lacked all three waxy proteins. DNA sequencing revealed three SNPs and a 3-bp InDel in the first exon, and a 16-bp InDel at the junction region of the first Wx-A1 intron from the Wx-null line. Six SNPs were identified in Wx-B1 gene of Wx-null line compared to the wild-type Gao 8901, including four missense mutations. One nonsense mutation was found at position 857 in the fourth exon, which resulted in a premature stop codon. Expression levels of Wx genes were dramatically reduced in the Wx-null line. Nonsense-mediated mRNA decay (NMD) may be triggered to degrade the non-functional Wx mRNA. There were no detectable differences in granule size and morphology between Wx-null and wild-type, but the Wx-null line contained a larger proportion of B-type starch granules. The amylose content of the Wx-null line (0.22%) was remarkably lower compared to the wild-type Gao 8901 (20.82%). Total starch is also lower in the Wx-null line. Conclusions: All three waxy proteins were non-functional in the Wx-null line. NMD may be the cause for reduced expression levels of Wx genes in the Wx-null line. The Wx-null line exhibited more B-type starch granules, dramatically lower amylose content, and decreased total starch. The Wx-null line may provide a potential waxy material with high agronomic performance in wheat breeding programs.

Research on Self-potential Base Line Drift Processing in Wangji Oilfield

<span style="font-family: &quot;Times New Roman&quot;,&quot;serif&quot;; font-size: 10pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA;" lang="EN-US">The positive amplitude anomalies and base line drifts of self-potential (SP) curves make it difficult to recognize the amplitude anomalies and impossible to carry on the standardized calibration. In this way, it becomes extremely hard to read the amplitude anomalies of self-potential curves, increasing the difficulty in lithology recognition and stratigraphic correlation. What’s more, it is impossible to apply the computer technology to do the batch processing. Aimed at the practical problems, taking advantages of the collected digital logging data, positive self-potential anomaly recognition and transformation models have been established, converting the positive anomalies in the sandstone intervals into negative ones, solving the problem of two types of amplitude anomalies in the same scale range. Self-potential base line drift processing moves the biased base line to the null line step by step, adopting the method of piecewise fitting differential migration. With satisfying results, the conformation, amplitude and jugged degree are accordant with the primary curve, forming the technique of self-potential curve processing, laying foundation for logging translation and geological research.</span>

Einstein-Like Lorentz Metrics and Three-Dimensional Curvature Homogeneity of Order One

We completely classify three-dimensional Lorentz manifolds, curvature homogeneous up to order one, equipped with Einstein-like metrics. New examples arise with respect to both homogeneous examples and three-dimensional Lorentz manifolds admitting a degenerate parallel null line field.