This protocol describes the processes involved in the generation of human antibody libraries in Fab format. The antibody repertoire is derived from peripheral blood mononucleocytes focusing on different immunoglobulin isotypes. A two-step cloning process was used to generate a diverse human Fab library for subsequent selection by phage display. The method can be applied for the generation of both naive and immune antibody libraries. The naive repertoire allows for the library to be applied for the generation of human monoclonal antibodies against a broad range of target antigens making it a useful resource for antibody generation. However, the immune repertoire will be focused against target antigens from a particular disease. The protocol will focus on the generation of the library including the panning process.
With major developments in molecular biology, numerous display technologies have been successfully introduced for recombinant antibody production. Even so, phage display still remains the gold standard for recombinant antibody production. Its success is mainly attributed to the robust nature of phage particles allowing for automation and adaptation to modifications. The generation of monospecific binders provides a vital tool for diagnostics at a lower cost and higher efficiency. The flexibility to modify recombinant antibodies allows great applicability to various platforms for use. This review presents phage display technology, application and modifications of recombinant antibodies for diagnostics.
The excitation functions were measured for the (nat)Cu(α,x)(66,67)Ga,(65)Zn,(57,58,60)Co reactions in the energy range of 16.5 -50MeV. A conventional stacked-foil activation technique combined with HPGe γ-ray spectrometry was employed to determine cross-sections. The measured cross-sections were critically compared with relevant previous experimental data and also with the evaluated data in the TENDL-2014 library. Present results confirmed some of the previous experimental data, whereas only a partial agreement was found with the evaluated data. The measured data are useful for reducing the existing discrepancies in the literature, to improve the nuclear reaction model codes, and to enrich the experimental database towards various applications.
Kejatuhan adalah isu kesihatan yang sering dikaitkan dengan warga emas di seluruh dunia. Kejatuhan boleh menyebabkan kesan negatif pada individu dan juga menyebabkan kematian dalam kes tertentu. Kajian semasa kejatuhan adalah amat terhad di Malaysia. Tujuan kajian ini adalah untuk merumuskan kajian semasa yang dijalankan di Malaysia yang mengenai prevalens dan ciri-cirinya. Artikel telah dikenalpasti melalui menggunakan pangkalan data elektronik berikut: EBSCOhost, ClinicalKey, ScienceDirect, Wiley Online Library, SpringerLink dan Google Scholar. Pemilihan artikel adalah terhad kepada artikel bahasa Inggeris yang diterbitkan antara tahun 2013 hingga 2019. Kajian ini menilai golongan warga emas yang berumur 60 tahun ke atas; sama ada di kediaman, komuniti atau institut perubatan. Sembilan artikel yang berkaitan telah dikenalpasti dan disiasat. Hasil kajian menunjukkan variasi yang ketara dengan julat 4-74 % dalam prevalens kejatuhan di kalangan warga emas di Malaysia. Salah satu kajian yang dijalankan dalam komuniti menunjukkan prevalens kejatuhan yang lebih rendah. Majoriti peristiwa kejatuhan berlaku pada waktu pagi seperti yang dilaporkan oleh tiga kajian iaitu sebanyak 49%-64.7%. Kejatuhan dalam kawasan bangunan adalah jumlah tertinggi lokasi jatuh dengan 50-87% manakala di luar bangunan adalah 13-49.3%. Lokasi di bilik mandi / tandas mempunyai peratusan kejatuhan tertinggi dalam bangunan. Kejatuhan yang menyebabkan kecederaan adalah antara 47% -82%. Perubahan pada prevalens kejatuhan dalam warga emas ditentukan oleh faktor-faktor seperti lokasi dan keadaan kesihatan. Maklumat yang dikumpulkan dalam kajian ini menunjukkan terdapat kekurangan alat ukur piawai bagi mengkaji ciri-ciri kejatuhan di Malaysia. Kajian prospektif diperlukan untuk menubuhkan prevalens dan hubungan faktor-kesan kejatuhan di Malaysia.
Green microalga Ankistrodesmus convolutus Corda is a fast growing alga which produces appreciable amount of carotenoids and polyunsaturated fatty acids. To our knowledge, this is the first report on the construction of cDNA library and preliminary analysis of ESTs for this species. The titers of the primary and amplified cDNA libraries were 1.1×10(6) and 6.0×10(9) pfu/ml respectively. The percentage of recombinants was 97% in the primary library and a total of 337 out of 415 original cDNA clones selected randomly contained inserts ranging from 600 to 1,500 bps. A total of 201 individual ESTs with sizes ranging from 390 to 1,038 bps were then analyzed and the BLASTX score revealed that 35.8% of the sequences were classified as strong match, 38.3% as nominal and 25.9% as weak match. Among the ESTs with known putative function, 21.4% of them were found to be related to gene expression, 14.4% ESTs to photosynthesis, 10.9% ESTs to metabolism, 5.5% ESTs to miscellaneous, 2.0% to stress response, and the remaining 45.8% were classified as novel genes. Analysis of ESTs described in this paper can be an effective approach to isolate and characterize new genes from A. convolutus and thus the sequences obtained represented a significant contribution to the extensive database of sequences from green microalgae.
The differential display method was used to isolate cDNAs corresponding to transcripts that accumulate during the period of lipid synthesis, 12-20 weeks after anthesis (WAA) in the mesocarp of two oil palms, Elaeis oleifera and Elaeis guineensis, Tenera. DNA-free total RNA from mesocarp and kernel of E. guineensis, Tenera and E. oleifera (15 WAA) were used to obtain differential gene expression patterns between these tissues from the two species. In this report, we describe the isolation and characterization of a specific cDNA clone, MO1 (434 bp) which was shown to be mesocarp-specific as well as species-specific for E. oleifera Sequencing of this fragment showed homology to the enzyme sesquiterpene synthase. Its longer cDNA clone, pMO1 (1072 bp), isolated from a 15-week E. oleifera mesocarp cDNA library confirmed that it encodes for sesquiterpene synthase. The complete sequence of 1976 bp was obtained using 5'RACE method. Northern hybridization showed that MO1 and pMO1 mRNA transcripts are highly expressed only in the mesocarp of E. oleifera from 5 to 20 WAA. No expression was detected in the kernel (12-17 WAA) and vegetative tissues of both species nor in the mesocarp of E. guineensis. This is the first communication to document on the isolation and characterisation of a mesocarp-and species-specific cDNA clone from oil palm.
Farah Fadwa Benbelgacem, Oualid Abdelkader Bellag, Adibah Parman, Ibrahim Ali Noorbatcha, Mohd Noor Mat Isa, Muhammad Alfatih Muddathir Abdelrahim, et al.
Metagenomic DNA library from palm oil mill effluent (POME) was constructed and subjected to high-throughput screening
to find genes encoding cellulose- and xylan-degrading enzymes. DNA of 30 positive fosmid clones were sequenced with next
generation sequencing technology and the raw data (short insert-paired) was analyzed with bioinformatic tools. First,
the quality of 64,821,599 reverse and forward sequences of 101 bp length raw data was tested using Fastqc and SOLEXA.
Then, raw data filtering was carried out by trimming low quality values and short reads and the vector sequences were
removed and again the output was checked and the trimming was repeated until a high quality read sets was obtained.
The second step was the de novo assembly of sequences to reconstruct 2900 contigs following de Bruijn graph algorithm.
Pre-assembled contigs were arranged in order, the distances between contigs were identified and oriented with SSPACE,
where 2139 scaffolds have been reconstructed. 16,386 genes have been identified after gene prediction using Prodigal
and putative ID assignment with Blastp vs NR protein. The acceptable strategy to handle metagenomic NGS-data in order
to detect known and potentially unknown genes is presented and we showed the computational efficiency of de Bruijn
graph algorithm of de novo assembly to 21 bioprospect genes encoding cellulose-degrading enzymes and 6 genes
encoding xylan-degrading enzymes of 30.3% to 100% identity percentage.
Cofactor-independent phosphoglycerate mutase has been proposed as a therapeutic target for the treatment of
trypanosomatid diseases. In this paper, we report the identification of compounds that could potentially be developed as
selective inhibitors of cofactor-independent phosphoglycerate mutase from Leishmania mexicana (LmiPGAM). Virtual
screening was used in this search, as well as compounds identified by high-throughput screening. A ligand-based virtual
screen programme, ultra fast shape recognition with atom types (UFSRAT), was used to screen for compounds resembling
the substrate/product, before a structure-based approach was applied using AutoDock 4 and AutoDock Vina in a consensus
docking scheme. In this way eight selected compounds were identified. In addition, three compounds from the Library of
Pharmacologically Active Compounds (LOPAC) were selected from the published results of high-throughput screening of
this library. The inhibitory effects of these compounds were tested at a fixed concentration of 1 mM. The results showed
that seven compounds inhibited LmiPGAM activity and of these, two compounds (one each from high-throughput and
virtual screening) showed substantial inhibition (i.e. 14% and 49% remaining activity, respectively). Taken together, the
findings from this study indicate that these compounds have potential as novel inhibitors that specifically target LmiPGAM.
A study of about 500 expressed sequence tags (ESTs), derived from a merozoite cDNA library, was initiated as an approach to generate a larger pool of gene information on Eimeria tenella. Of the ESTs, 47.7% had matches with entries in the databases, including ribosomal proteins, metabolic enzymes and proteins with other functions, of which 14.3% represented previously known E. tenella genes. Thus over 50% of the ESTs had no significant database matches. The E. tenella EST dataset contained a range of highly abundant genes comparable with that found in the EST dataset of T. gondii and may thus reflect the importance of such molecules in the biology of the apicomplexan organisms. However, comparison of the two datasets revealed very few homologies between sequences of apical organelle molecules, and provides evidence for sequence divergence between these closely-related parasites. The data presented underpin the potential value of the EST strategy for the discovery of novel genes and may allow for a more rapid increase in the knowledge and understanding of gene expression in the merozoite life cycle stage of Eimeria spp.
Knowledge on the precise identification of fish resources is critical for sustainable fisheries management. This study employs the DNA barcoding approach to generate a molecular taxonomic catalogue of commercially important reef fishes in the waters of Weh Island (Aceh Province), the most northerly inhabited island in the biodiverse Indonesian Archipelago. The waters not only support artisanal fisheries but also a feeder for the industry in the greater island of Aceh. In total, 230 specimens from 72 species belonging to 32 genera and 17 families were DNA barcoded, representing a major segment of the captured reef fish taxa and a quarter of fish species diversity that had previously been recorded. The sequence read lengths were 639 bp revealing 359 conserved sites, 280 variable sites, 269 parsimony informative and 11 singletons. Our molecular findings paralleled the morphological identification with no evidence of cryptic species or new species discovery. This study is a significant contribution to the fisheries statistics of this area, which would facilitate assessment of species catch composition and hence for strategizing management plans. It is an important input to the DNA barcode library of Indonesian marine fishes and to the global DNA barcode entries in general.
Burkholderia cenocepacia infection often leads to fatal cepacia syndrome in cystic fibrosis patients. However, antibiotic therapy rarely results in complete eradication of the pathogen due to its intrinsic resistance to many clinically available antibiotics. Recent attention has turned to the identification of essential genes as the proteins encoded by these genes may serve as potential targets for development of novel antimicrobials. In this study, we utilized TraDIS (Transposon Directed Insertion-site Sequencing) as a genome-wide screening tool to facilitate the identification of B. cenocepacia genes essential for its growth and viability. A transposon mutant pool consisting of approximately 500,000 mutants was successfully constructed, with more than 400,000 unique transposon insertion sites identified by computational analysis of TraDIS datasets. The saturated library allowed for the identification of 383 genes that were predicted to be essential in B. cenocepacia. We extended the application of TraDIS to identify conditionally essential genes required for in vitro growth and revealed an additional repertoire of 439 genes to be crucial for B. cenocepacia growth under nutrient-depleted conditions. The library of B. cenocepacia mutants can subsequently be subjected to various biologically related conditions to facilitate the discovery of genes involved in niche adaptation as well as pathogenicity and virulence.
This paper describes the first reported attempt to isolate DNA sequences containing repeat motifs in Eurycoma longifolia and Orthosiphon stamineus. A library enriched for genomic repeat motifs was developed using novel oligonucleotides designed with inosine residues incorporated at predetermined positions. A total of eight and twelve specific molecular markers were developed for O. stamineus and E. longifolia respectively. These markers have a potential application in estimating population diversity levels and QTL mapping in these two medicinal plants, which are widely used in the Malaysian herbal industry.
Mammal diversity assessments based on DNA derived from invertebrates have been suggested as alternatives to assessments based on traditional methods; however, no study has field-tested both approaches simultaneously. In Peninsular Malaysia, we calibrated the performance of mammal DNA derived from blowflies (Diptera: Calliphoridae) against traditional methods used to detect species. We first compared five methods (cage trapping, mist netting, hair trapping, scat collection, and blowfly-derived DNA) in a forest reserve with no recent reports of megafauna. Blowfly-derived DNA and mist netting detected the joint highest number of species (n = 6). Only one species was detected by multiple methods. Compared to the other methods, blowfly-derived DNA detected both volant and non-volant species. In another forest reserve, rich in megafauna, we calibrated blowfly-derived DNA against camera traps. Blowfly-derived DNA detected more species (n = 11) than camera traps (n = 9), with only one species detected by both methods. The rarefaction curve indicated that blowfly-derived DNA would continue to detect more species with greater sampling effort. With further calibration, blowfly-derived DNA may join the list of traditional field methods. Areas for further investigation include blowfly feeding and dispersal biology, primer biases, and the assembly of a comprehensive and taxonomically-consistent DNA barcode reference library.
Degradome sequencing referred as parallel analysis of RNA ends (PARE) by modifying 5'-rapid amplification of cDNA ends (RACE) with deep sequencing method. Deep sequencing of 5' products allow the determination of cleavage sites through the mapping of degradome fragments against small RNAs (miRNA or siRNA) on a large scale. Here, we carried out degradome sequencing in medicinal plant, Persicaria minor, to identify cleavage sites in small RNA libraries in control (mock-inoculated) and Fusarium oxysporum treated plants. The degradome library consisted of both control and treated samples which were pooled together during library preparation and named as D4. The D4 dataset have been deposited at GenBank under accession number SRX3921398, https://www.ncbi.nlm.nih.gov/sra/SRX3921398.
Interest in harvesting potential benefits from microalgae renders it necessary to have the many ecological niches of a single species to be investigated. This dataset comprises de novo whole genome assembly of two mangrove-isolated microalgae (from division Chlorophyta); Chlorella vulgaris UMT-M1 and Messastrum gracile SE-MC4 from Universiti Malaysia Terengganu, Malaysia. Library runs were carried out with 2 × 150 base paired-ends reads, whereas sequencing was conducted using Illumina Novaseq 2500 platform. Sequencing yielded raw reads amounting to ∼11 Gb in total bases for both species and was further assembled de novo. Genome assembly resulted in a 50.15 Mbp and 60.83 Mbp genome size for UMT-M1 and SE-MC4, respectively. All filtered and assembled genomic data sequences have been submitted to National Centre for Biotechnology Information (NCBI) and can be located at DDBJ/ENA/GenBank under the accession of VJNP00000000 (UMT-M1) and VIYE00000000 (SE-MC4).
RNA-seq has become an essential tool in molecular research. Nevertheless, application of RNA-seq was limited by cost and technical difficulties. Illumina has introduced the cost effective and ease to handle Truseq Targeted RNA Sequencing. In this study, we present the requirements and the optimization procedure for this Truseq Targeted RNA sequencing on cell line. Total RNA was recommended as starting materials but it required optimization including additional purification step and adjusting the AMPure beads ratio to eliminate unwanted contaminants. This can be resolved by using PolyA-enriched mRNA as starting material. TREx is a useful assay to evaluate gene expression. Quality library of TREx can be prepared by adding multiple washing steps or changing input sample to mRNA.
Phage display has been applied successfully for the rapid isolation of monoclonal antibodies against various targets including infectious diseases, autoantigens, cancer markers, and even small molecules. The main component in any phage display experiment is the availability of an antibody library to carry out the selection process of target-specific antibodies through an iterative process termed as biopanning. To generate human antibody libraries, the antibody repertoire can be obtained from human peripheral blood mononuclear cell (PBMC) or directly from cell-sorted B-cell populations. The choice of antibody isotype is dictated by the nature of the library. Naïve libraries would utilize IgM repertoires, whereas the IgG repertoire is commonly used for immune libraries. Antibody genes are amplified through polymerase chain reaction (PCR) and paired in a combinatorial fashion to expand the diversity of the cloned library repertoire. The protocol here describes the use of a two-step cloning method that can be applied for the construction of either a naïve or immune human antibody library in Fab format followed by the subsequent panning.
MicroRNAs (miRNAs) are small RNAs (sRNAs) with approximately 21-24 nucleotides in length. They regulate the expression of target genes through the mechanism of RNA silencing. Conventional isolation and cloning of miRNAs methods are usually technical demanding and inefficient. These limitations include the requirement for high amounts of starting total RNA, inefficient ligation of linkers, high amount of PCR artifacts and bias in the formation of short miRNA-concatamers. Here we describe in detail a method that uses 80 μg of total RNA as the starting material. Enhancement of the ligation of sRNAs and linkers with the use of polyethylene glycol (PEG8000) was described. PCR artifacts from the amplification of reverse-transcribed sRNAs were greatly decreased by using lower concentrations of primers and reducing the number of amplification cycles. Large concatamers with up to 1 kb in size with around 20 sRNAs/concatamer were obtained by using an optimized reaction condition. This protocol provide researchers with a rapid, efficient and cost-effective method for the construction of miRNA profiles from plant tissues containing low amounts of total RNA, such as fruit flesh and senescent leaves.
Directed evolution of nucleotide libraries using recombination or mutagenesis is an important technique for customizing catalytic or biophysical traits of proteins. Conventional directed evolution methods, however, suffer from cumbersome digestion and ligation steps. Here, we describe a simple method to increase nucleotide diversity using single-stranded DNA (ssDNA) as a starting template. An initial PCR amplification using phosphorylated primers with overlapping regions followed by treatment with lambda exonuclease generates ssDNA templates that can then be annealed via the overlap regions. Double-stranded DNA (dsDNA) is then generated through extension with Klenow fragment. To demonstrate the applicability of this methodology for directed evolution of nucleotide libraries, we generated both gene shuffled and regional mutagenesis synthetic antibody libraries with titers of 2×108 and 6×107, respectively. We conclude that our method is an efficient and convenient approach to generate diversity in nucleic acid based libraries, especially recombinant antibody libraries.
Calamus palustris Griff. is an economically important dioecious rattan species in Southeast Asia. However, dioecy and onset of flowering at 3-4 years old render uncertainties in desired female:male seedling ratios to establish a productive seed orchard for this rattan species. We constructed a subtractive library for male floral tissue to understand the genetic mechanism for gender determination in C. palustris. The subtractive library produced 1536 clones with 1419 clones of high quality. Reverse Northern screening showed 313 clones with differential expression, and sequence analyses clustered them into 205 unigenes, including 32 contigs and 173 singletons. The subtractive library was further validated with reverse transcription-quantitative polymerase chain reaction analysis. Homology identification classified the unigenes into 12 putative functional proteins with 83% unigenes showing significant match to proteins in databases. Functional annotations of these unigenes revealed genes involved in male flower development, including MADS-box genes, pollen-related genes, phytohormones for flower development, and male flower organ development. Our results showed that the male floral genes may play a vital role in sex determination in C. palustris. The identified genes can be exploited to understand the molecular basis of sex determination in C. palustris.