Antes de Johann Gregor Mendel y la presentación de su obra "Experiments in plant hybridization" (1865), existieron diversos experimentadores que trabajaron con variedades de plantas y razas de ...animales de diversas especies, con el fin de obtener organismos con atributos deseables por su valor estético, económico y alimentario. Sin embargo, no lograron establecer principios generales. Mendel por su parte, poseía una formación académica sólida y de manera excepcional elige al chícharo Pisum sativum como sistema experimental. La especie posee diversas ventajas, tales como: acceso fácil a numerosas variedades comerciales, costo bajo, ciclos cortos y requiere de espacios pequeños. Mendel confirmó que fueran líneas puras, hizo diseños de cruzas experimentales que llevó a cabo, recolectó miles de datos obtenidos a partir de cientos de individuos, organizó la información recabada y la analizó. A partir de los datos logró establecer conclusiones brillantes e hizo las inferencias que hoy se conocen como las leyes de la segregación y la distribución independiente de los caracteres dominantes y recesivos, términos que él mismo aplicó. Los experimentos son reproducibles y se pueden hacer predicciones de los resultados esperados. Los principios siguen vigentes y son aplicables a todas las especies diploides con reproducción sexual. Durante el siglo XX se conocieron diversas excepciones a las leyes, que no las invalidan, sino que amplían el espectro de los mecanismos genéticos conocidos, entre los que destacan: la dominancia incompleta, ligamiento de genes, interacciones génicas, entre otras. Es notable que hasta la década de 1990 se llegaran a conocer algunos de los mecanismos moleculares que intervienen en la expresión de las cualidades mendelianas de los chícharos. Las aplicaciones de las leyes de Mendel son vigentes y de enorme utilidad en los campos de la Genética humana, Genética animal y de plantas. Un ejemplo notable es el catálogo de rasgos y desórdenes mendelianos de Victor A. McKusick "Mendelian Inheritance in Man" (MIM) con doce ediciones publicadas entre 1966 y 1998, así como su versión en línea OMIM. También son destacados los cientos de caracteres mendelianos que son conocidos de la mosca Drosophila melanogaster y de numerosas variedades de maíz. Sin embargo, hasta la fecha se han estudiado las cualidades mendelianas de pocas especies, en relación con los miles que se estima habitan el planeta: vertebrados (56 mil), moluscos (80 mil), plantas (276 mil) y cientos de miles de otras formas de vida. Por lo tanto, la Genética mendeliana tiene mucho que aportar al conocimiento de la biodiversidad conocida y de la que falta por descubrir.
Imaging the transcriptome in situ with high accuracy has been a major challenge in single-cell biology, which is particularly hindered by the limits of optical resolution and the density of ...transcripts in single cells
. Here we demonstrate an evolution of sequential fluorescence in situ hybridization (seqFISH+). We show that seqFISH+ can image mRNAs for 10,000 genes in single cells-with high accuracy and sub-diffraction-limit resolution-in the cortex, subventricular zone and olfactory bulb of mouse brain, using a standard confocal microscope. The transcriptome-level profiling of seqFISH+ allows unbiased identification of cell classes and their spatial organization in tissues. In addition, seqFISH+ reveals subcellular mRNA localization patterns in cells and ligand-receptor pairs across neighbouring cells. This technology demonstrates the ability to generate spatial cell atlases and to perform discovery-driven studies of biological processes in situ.
Objective To validate and determine the best array–comparative genomic hybridization (aCGH; array-CGH) protocols for preimplantation genetic screening (PGS). Design Embryos had one cell removed as a ...biopsy specimen and analyzed by one of two array-CGH protocols. Abnormal embryos were reanalyzed by fluorescence in situ hybridization (FISH). Setting Reference laboratory. Patient(s) Patients donating embryos or undergoing PGS. Intervention(s) Embryo biopsy, array-CGH, FISH reanalysis. Main Outcome Measure(s) Diagnosis, no result rate and error rate. Result(s) Method one produced 11.2% of embryos with no results and a 9.1% error rate compared with 3% and 1.9% for method two, respectively. Thereafter, only method two was used clinically. The aneuploidy rate for cleavage-stage embryos was 63.2%, significantly increasing with maternal age. The chromosomes most involved in aneuploidy were 16, 22, 21, and 15. We report the first live births after array-CGH combined with single blastomere biopsy. Conclusion(s) Array-CGH is proved to be highly robust (2.9% no results) and specific (1.9% error rate) when applied to rapid (24-hour) analysis of single cells biopsied from cleavage-stage embryos. This comprehensive chromosome analysis technique is the first to be validated by reanalyzing the same embryos with another technique (e.g., FISH). Unlike some alternative techniques for comprehensive chromosome screening, array-CGH does not require prior testing of parental DNA and thus advance planning and careful scheduling are unnecessary.
García‐García E, Gómez‐Martín C, Angulo B, Conde E, Suárez‐Gauthier A, Adrados M, Perna C, Rodríguez‐Peralto J L, Hidalgo M & López‐Ríos F (2011) Histopathology59, 8–17
Hybridization for human ...epidermal growth factor receptor 2 testing in gastric carcinoma: a comparison of fluorescence in‐situ hybridization with a novel fully automated dual‐colour silver in‐situ hybridization method
Aims: Amplification of the human epidermal growth factor receptor 2 (HER2) gene has been reported in gastric carcinoma (GC). Accordingly, trastuzumab plus chemotherapy has recently become the new standard treatment for HER2‐positive advanced GCs. The aim was to compare the alleged gold standard for hybridization fluorescence in‐situ hybridization (FISH) with a novel, fully automated brightfield dual‐colour silver‐enhanced in‐situ hybridization (SISH) method.
Methods and results: The studies series was comprised of 166 GC samples. Additionally, tumours with discordant results obtained by FISH and SISH were analysed by real‐time quantitative polymerase chain reaction (PCR) with the LightMix kit HER‐2/neu. Of the samples, 17.5% and 21% were amplified by FISH and SISH, respectively. Heterogeneity was identified in up to 52% of cases. In 96.4% of cases, FISH showed the same results as SISH. All six discordant cases were positive by SISH and negative by FISH. On review of the FISH slides, all contradictory cases were polysomic and were confirmed to be negative for amplification by real‐time PCR. Interestingly, all ratios in this latter group were between 2.06 and 2.50, so setting the cut‐off for amplification at ≥3 resulted in perfect concordance.
Conclusions: Dual‐colour SISH represents a novel method for the determination of HER2 status in GC.
A revision on condition (27) of Lemma 3.2 of Babaie-Kafaki (J. Optim. Theory Appl. 154(3):916âeuro"932, 2012 ) is made. Throughout, we use the same notation and equation numbers as in Babaie-Kafaki ...(J. Optim. Theory Appl. 154(3):916âeuro"932, 2012 ).PUBLICATION ABSTRACT
Aims
The wide variety of affected organ systems associated with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection highlights the need for tissue‐specific evaluation. We compared ...placentas from SARS‐CoV‐2‐positive and SARS‐CoV‐2‐negative women in our hospital in New York City, which became the epicenter of the coronavirus disease 2019 pandemic in March 2020. To date, some limited studies have been published on placentas from SARS‐CoV‐2‐positive women. The aim of our study, in addition to describing histomorphology, was to utilize in‐situ hybridization (ISH) for the S‐gene encoding the spike protein and immunohistochemistry (IHC) with the monoclonal SARS‐CoV‐2 spike antibody 1A9 for placental evaluation.
Methods and results
In this study, 51 singleton, third‐trimester placentas from SARS‐CoV‐2‐positive women and 25 singleton, third‐trimester placentas from SARS‐CoV‐2‐negative women were examined histomorphologically according to the Amsterdam Criteria and with ISH and/or IHC. The corresponding clinical findings and neonatal outcomes also were recorded. Although no specific histomorphologic changes related to SARS‐CoV‐2 were noted in the placentas, evidence of maternal–fetal vascular malperfusion was identified, with placentas from SARS‐CoV‐2‐positive women being significantly more likely to show villous agglutination (P = 0.003) and subchorionic thrombi (P = 0.026) than placentas from SARS‐CoV‐2‐negative women. No evidence of direct viral involvement was identified with ISH and IHC.
Conclusions
In this study, third‐trimester placentas from SARS‐CoV‐2‐positive women were more likely to show evidence of maternal–fetal vascular malperfusion; however, ISH and IHC provided no evidence of direct viral involvement or vertical transmission.
Key message
A wheat-rye 4R chromosome disomic addition line with resistances to powdery mildew, stripe rust, sharp eyespot and high kernel number per spike was developed and characterized by ...molecular cytogenetic method as novel resistant germplasm.
Rye (
Secale cereale
L.), a close relative of common wheat, is an important and valuable gene donor with multiple disease resistance for wheat improvement. However, resistance genes derived from rye have successively lost resistance to pathogens due to the coevolution of pathogen virulence and host resistance. Development and identification of new effective resistance gene sources from rye therefore are of special importance and urgency. In the present study, a wheat-rye line WR35 was produced through distant hybridization, embryo rescue culture, chromosome doubling and backcrossing. WR35 was then proven to be a new wheat-rye 4R disomic addition line using sequential GISH (genomic in situ hybridization), mc-FISH (multicolor fluorescence in situ hybridization) and ND-FISH (non-denaturing FISH) with multiple probes, mc-GISH (multicolor GISH), rye chromosome arm-specific marker analysis and SLAF-seq (specific-locus amplified fragment sequencing) analysis. At the adult stage, WR35 exhibited high levels of resistance to the powdery mildew (
Blumeria graminis
f. sp.
tritici
,
Bgt
) and stripe rust (
Puccinia striiformis
f. sp.
tritici
,
Pst
) pathogens prevalent in China, and a highly virulent isolate of
Rhizoctonia cerealis
, the cause of wheat sharp eyespot. At the seedling stage, it was highly resistant to 22 of 23
Bgt
isolates and four
Pst
races. Based on its disease responses to different pathogen isolates, WR35 may possess resistance gene(s) for powdery mildew, stripe rust and sharp eyespot, which differed from the known resistance genes from rye. In addition, WR35 was cytologically stable and produced high kernel number per spike. Therefore, WR35 with multi-disease resistances and desirable agronomic traits should serve as a promising bridging parent for wheat chromosome engineering breeding.
•MS-biochar exhibited better catalytic ability than GP, GO and MWCNT.•ASS was the most important contributor for MS-400/600 while CM dominated MS-800.•ASS was effective for SO4− formation and CM was ...primarily committed to OH.•Iron compounds, doped-nitrogen and graphitic carbon were proved as catalytic sites.•Two internal electron transfer paths among MS-biochar’s CM were proposed.
Persulfate-based advanced oxidation process is a powerful countermeasure for water remediation, where effective and low-cost catalysts are still needed. Herein, a one-pot synthetic method for magnetic nitrogen-doped sludge biochar (MS-biochar) was presented, which exhibited better catalytic property with PDS for tetracycline degradation than typical graphitic carbon (graphite powder, graphene oxide and multiwalled carbon nanotubes) and two other types biochars. EDAX manifested the uniform dispersion of elements in MS-biochar. Similar to “top-down”, a research thought from whole to part of MS-biochar for contribution measurement was presented, where acid-soluble substance (ASS) was the most important contributor for MS-400/600 while carbon matrix (CM) was dominant for MS-800. Quenching and EPR demonstrated a free-radicals pathway in MS-biochar/PDS, where ASS mainly assumed to be effective for SO4− and CM was primarily committed to OH generation. EDAX, XPS and Raman studies proved three kinds of catalytic sites, namely the iron compounds, doped nitrogen and graphitic carbon. And their activating mechanism were discussed where one internal electron migration path (from sp3 to nanocrystalline sp2 carbon) has been first proposed. Reusability, metal leaching detection and pharmaceutical wastewater application indicated the potential of MS-biochar. This work not only presents a potential resource-based disposal of sewage sludge, a novel research thought from whole to part for materials performance measurement, but also provides guidance for carbon materials’ design for persulfate activation, especially for sp2 and sp3 co-hybridized carbons.
Hybridization has long been considered a process that prevents divergence between species. In contrast to this historical view, an increasing number of empirical studies claim to show evidence for ...hybrid speciation without a ploidy change. However, the importance of hybridization as a route to speciation is poorly understood, and many claims have been made with insufficient evidence that hybridization played a role in the speciation process. We propose criteria to determine the strength of evidence for homoploid hybrid speciation. Based on an evaluation of the literature using this framework, we conclude that although hybridization appears to be common, evidence for an important role of hybridization in homoploid speciation is more circumscribed.
PDF
