Local Enrichment with Convergence of Enriched T-Cell Clones Are Hallmarks of Effective Peptide Vaccination against B16 Melanoma.

BACKGROUND: Some peptide anticancer vaccines elicit a strong T-cell memory response but fail to suppress tumor growth. To gain insight into tumor resistance, we compared two peptide vaccines, p20 and p30, against B16 melanoma, with both exhibiting good in vitro T-cell responses but different tumor suppression abilities. METHODS: We compared activation markers and repertoires of T-lymphocytes from tumor-draining (dLN) and non-draining (ndLN) lymph nodes for the two peptide vaccines. RESULTS: We showed that the p30 vaccine had better tumor control as opposed to p20. p20 vaccine induced better in vitro T-cell responsiveness but failed to suppress tumor growth. Efficient antitumor vaccination is associated with a higher clonality of cytotoxic T-cells (CTLs) in dLNs compared with ndLNs and the convergence of most of the enriched clones. With the inefficient p20 vaccine, the most expanded and converged were clones of the bystander T-cells without an LN preference. CONCLUSIONS: Here, we show that the clonality and convergence of the T-cell response are the hallmarks of efficient antitumor vaccination. The high individual and methodological dependencies of these parameters can be avoided by comparing dLNs and ndLNs.

The Relationship between Lifespan of Marine Bivalves and Their Fatty Acids of Mitochondria Lipids.

Marine bivalves belonging to the Mytilidae and Pectinidae Families were used in this research. The specific objectives of this study were: to determine the Fatty Acids (FAs) of mitochondrial gill membranes in bivalves with different lifespans, belonging to the same family, and to calculate their peroxidation index; to compare the levels of ROS generation, malondialdehyde (MDA), and protein carbonyls in the mitochondria of gills, in vitro, during the initiation of free-radical oxation; to investigate whether the FAs of mitochondria gill membranes affect the degree of their oxidative damage and the maximum lifespan of species (MLS). The qualitative membrane lipid composition was uniform in the studied marine bivalves, regardless of their MLS. In terms of the quantitative content of individual FAs, the mitochondrial lipids differed significantly. It is shown that lipid matrix membranes of the mitochondria of long-lived species are less sensitive to in vitro-initiated peroxidation compared with the medium and short-lived species. The differences in MLS are related to the peculiarities of FAs of mitochondrial membrane lipids.

Genetically encodable bioluminescent system from fungi.

Bioluminescence is found across the entire tree of life, conferring a spectacular set of visually oriented functions from attracting mates to scaring off predators. Half a dozen different luciferins, molecules that emit light when enzymatically oxidized, are known. However, just one biochemical pathway for luciferin biosynthesis has been described in full, which is found only in bacteria. Here, we report identification of the fungal luciferase and three other key enzymes that together form the biosynthetic cycle of the fungal luciferin from caffeic acid, a simple and widespread metabolite. Introduction of the identified genes into the genome of the yeast Pichia pastoris along with caffeic acid biosynthesis genes resulted in a strain that is autoluminescent in standard media. We analyzed evolution of the enzymes of the luciferin biosynthesis cycle and found that fungal bioluminescence emerged through a series of events that included two independent gene duplications. The retention of the duplicated enzymes of the luciferin pathway in nonluminescent fungi shows that the gene duplication was followed by functional sequence divergence of enzymes of at least one gene in the biosynthetic pathway and suggests that the evolution of fungal bioluminescence proceeded through several closely related stepping stone nonluminescent biochemical reactions with adaptive roles. The availability of a complete eukaryotic luciferin biosynthesis pathway provides several applications in biomedicine and bioengineering.

Improved DOP-PCR (iDOP-PCR): A robust and simple WGA method for efficient amplification of low copy number genomic DNA.

Whole-genome amplification (WGA) techniques are used for non-specific amplification of low-copy number DNA, and especially for single-cell genome and transcriptome amplification. There are a number of WGA methods that have been developed over the years. One example is degenerate oligonucleotide-primed PCR (DOP-PCR), which is a very simple, fast and inexpensive WGA technique. Although DOP-PCR has been regarded as one of the pioneering methods for WGA, it only provides low genome coverage and a high allele dropout rate when compared to more modern techniques. Here we describe an improved DOP-PCR (iDOP-PCR). We have modified the classic DOP-PCR by using a new thermostable DNA polymerase (SD polymerase) with a strong strand-displacement activity and by adjustments in primers design. We compared iDOP-PCR, classic DOP-PCR and the well-established PicoPlex technique for whole genome amplification of both high- and low-copy number human genomic DNA. The amplified DNA libraries were evaluated by analysis of short tandem repeat genotypes and NGS data. In summary, iDOP-PCR provided a better quality of the amplified DNA libraries compared to the other WGA methods tested, especially when low amounts of genomic DNA were used as an input material.

A high-throughput assay for quantitative measurement of PCR errors.

The accuracy with which DNA polymerase can replicate a template DNA sequence is an extremely important property that can vary by an order of magnitude from one enzyme to another. The rate of nucleotide misincorporation is shaped by multiple factors, including PCR conditions and proofreading capabilities, and proper assessment of polymerase error rate is essential for a wide range of sensitive PCR-based assays. In this paper, we describe a method for studying polymerase errors with exceptional resolution, which combines unique molecular identifier tagging and high-throughput sequencing. Our protocol is less laborious than commonly-used methods, and is also scalable, robust and accurate. In a series of nine PCR assays, we have measured a range of polymerase accuracies that is in line with previous observations. However, we were also able to comprehensively describe individual errors introduced by each polymerase after either 20 PCR cycles or a linear amplification, revealing specific substitution preferences and the diversity of PCR error frequency profiles. We also demonstrate that the detected high-frequency PCR errors are highly recurrent and that the position in the template sequence and polymerase-specific substitution preferences are among the major factors influencing the observed PCR error rate.

Quantitative profiling of immune repertoires for minor lymphocyte counts using unique molecular identifiers.

Emerging high-throughput sequencing methods for the analyses of complex structure of TCR and BCR repertoires give a powerful impulse to adaptive immunity studies. However, there are still essential technical obstacles for performing a truly quantitative analysis. Specifically, it remains challenging to obtain comprehensive information on the clonal composition of small lymphocyte populations, such as Ag-specific, functional, or tissue-resident cell subsets isolated by sorting, microdissection, or fine needle aspirates. In this study, we report a robust approach based on unique molecular identifiers that allows profiling Ag receptors for several hundred to thousand lymphocytes while preserving qualitative and quantitative information on clonal composition of the sample. We also describe several general features regarding the data analysis with unique molecular identifiers that are critical for accurate counting of starting molecules in high-throughput sequencing applications.

A strong strand displacement activity of thermostable DNA polymerase markedly improves the results of DNA amplification.

The sensitivity and robustness of various DNA detection and amplification techniques are to a large extent determined by the properties of the DNA polymerase used. We have compared the performance of conventional Taq and Bst DNA polymerases to a novel Taq DNA polymerase mutant (SD DNA polymerase), which has a strong strand displacement activity, in PCR (including amplification of GC-rich and complex secondary structure templates), long-range PCR (LR PCR), loop-mediated amplification (LAMP), and polymerase chain displacement reaction (PCDR). Our results demonstrate that the strand displacement activity of SD DNA polymerase, in combination with the robust polymerase activity, provides a notable improvement in the sensitivity and efficiency of all these methods.

Normalization of full-length-enriched cDNA.

A well-recognized obstacle to efficient high-throughput analysis of cDNA libraries is the differential abundance of various transcripts in any particular cell type. Decreasing the prevalence of clones representing abundant transcripts before sequencing, using cDNA normalization, may significantly increase the efficacy of random sequencing and is essential for rare gene discovery. Duplex-specific nuclease (DSN) normalization allows the generation of normalized full-length-enriched cDNA libraries to permit a high gene discovery rate. The method is based on the unique properties of DSN from the Kamchatka crab and involves denaturation-reassociation of cDNA, degradation of the ds-fraction formed by abundant transcripts by DSN, and PCR amplification of the remaining ss-DNA fraction. The method has been evaluated in various plant and animal models.

Normalizing cDNA libraries.

The characterization of rare messages in cDNA libraries is complicated by the substantial variations that exist in the abundance levels of different transcripts in cells and tissues. The equalization (normalization) of cDNA is a helpful approach for decreasing the prevalence of abundant transcripts, thereby facilitating the assessment of rare transcripts. This unit provides a method for duplex-specific nuclease (DSN)-based normalization, which allows for the fast and reliable equalization of cDNA, thereby facilitating the generation of normalized, full-length-enriched cDNA libraries, and enabling efficient RNA analyses.

Thermolabile duplex-specific nuclease.

Using random mutagenesis of the gene encoding duplex-specific nuclease from the king crab we found a new mutant that retained all properties of the wild-type protein, but exhibited a much lower thermal stability. This enzyme, denoted thermolabile duplex-specific nuclease (DSN-TL), exhibits high processivity and selective cleavage of dsDNA. The inactivation temperature for DSN-TL is 15-20 degrees C lower than that of the widely used DNase I and shrimp nuclease, and its catalytic activity is more than 10 times higher. Moreover, DSN-TL is resistant to proteinase K treatment. These properties make DSN-TL very useful for removing genomic DNA from RNA samples intended for quantitative RT-PCR.

Is crab duplex-specific nuclease a member of the Serratia family of non-specific nucleases?

Kamchatka crab duplex-specific nuclease (Par_DSN) has been classified as a member of the family of DNA/RNA non-specific beta-beta-alpha metal finger (bba-Me-finger) nucleases, the archetype of which is the nuclease from Serratia marcescens. Although the enzyme under investigation seems to belong to the family of S. marcescens nucleases, Par_DSN exhibits a marked preference for double-stranded DNA as a substrate and this property is unusual for other members of this family. We have searched other Arthropod species and identified a number of novel Par_DSN homologs. A phylogenetic analysis demonstrates that the Par_DSN-like enzymes constitute a separate branch in the evolutionary tree of bba-Me-finger nucleases. Combining sequence analysis and site-directed mutagenesis, we found that Par_DSN and its homologs possess the nuclease domain that is slightly longer than that of classic Serratia relatives. The active site composition of Par_DSN is similar but not identical to that of classic Serratia nucleases. Based on these findings, we proposed a new classification of Par_DSN-like nucleases.

Transcriptional and metabolic profiles of stress-induced, embryogenic tobacco microspores.

Higher plant microspores, when subjected to various stress treatments in vitro, are able to reprogram their regular gametophytic development towards the sporophytic pathway to form haploid embryos and plants. Suppression subtractive hybridization (SSH) and metabolic profiling were used to characterize this developmental switch. Following differential reverse Northern hybridizations 90 distinct up-regulated sequences were identified in stressed, embryogenic microspores (accessible at www.univie.ac.at/ntsm). Sequence analyses allowed the classification of these genes into functional clusters such as metabolism, chromosome remodeling, signaling, transcription and translation, while the putative functions of half of the sequences remained unknown. A comparison of metabolic profiles of non-stressed and stressed microspores using gas chromatography/mass spectrometry (GC/MS) identified 70 compounds, partly displaying significant changes in metabolite levels, e.g., highly elevated levels of isocitrate and isomaltose in stressed microspores compared to non-stressed microspores. The formation of embryogenic microspores is discussed on the basis of the identified transcriptional and metabolic profiles.

Amino acid sequence of RTX-A's isoform actinoporin from the sea anemone, Radianthus macrodactylus.

The amino acid sequence of actinoporin RTX-A (175 aa) from the sea anemone Radianthus macrodactylus was determined by sequencing of clones obtained via amplification of cDNA. It was established that RTX-A possessed high homology with HmgIII from Heteractis magnifica (87%) and StI, StII from Stichodactyla helianthus (84 and 87%, respectively). The analysis of structural and functional relationships within RTX-A was carried out. The some disagreement concerning to significant role of several amino acid residues for actinoporins exhibition of hemolytic activity was found.

GFP-like proteins as ubiquitous metazoan superfamily: evolution of functional features and structural complexity.

Homologs of the green fluorescent protein (GFP), including the recently described GFP-like domains of certain extracellular matrix proteins in Bilaterian organisms, are remarkably similar at the protein structure level, yet they often perform totally unrelated functions, thereby warranting recognition as a superfamily. Here we describe diverse GFP-like proteins from previously undersampled and completely new sources, including hydromedusae and planktonic Copepoda. In hydromedusae, yellow and nonfluorescent purple proteins were found in addition to greens. Notably, the new yellow protein seems to follow exactly the same structural solution to achieving the yellow color of fluorescence as YFP, an engineered yellow-emitting mutant variant of GFP. The addition of these new sequences made it possible to resolve deep-level phylogenetic relationships within the superfamily. Fluorescence (most likely green) must have already existed in the common ancestor of Cnidaria and Bilateria, and therefore GFP-like proteins may be responsible for fluorescence and/or coloration in virtually any animal. At least 15 color diversification events can be inferred following the maximum parsimony principle in Cnidaria. Origination of red fluorescence and nonfluorescent purple-blue colors on several independent occasions provides a remarkable example of convergent evolution of complex features at the molecular level.

Identification and characterization of a new family of C-type lectin-like genes from planaria Girardia tigrina.

A novel family of C-type lectin-like genes, denoted multidomain free lectin (MDFL), was identified in the freshwater planaria Girardia (Dugesia) tigrina. We cloned several genes that encode proteins comprising a signal peptide and a number of consecutive C-type lectin-like domains (CTLDs) interconnected by short linker stretches. Analyses of genomic organization, CTLD amino acid sequences, and the overall architecture of these proteins indicate that planarian proteins are a separate family of C-type lectin-like proteins. These genes are expressed in specifically differentiated gland cells of planaria and the corresponding proteins are excreted as components of the planarian body surface mucus.

Antirrhinum majus microspore maturation and transient transformation in vitro.

The male gametophyte of higher plants represents an excellent system to study gene regulation, cell fate determination and cellular differentiation in plants because of its relative simplicity compared to the sporophyte and its accessibility for cytological and molecular analysis. Unicellular plant microspores are single haploid cells, which can be isolated in large amounts at a defined developmental stage. Microspores cultured in vitro in a rich medium develop into mature pollen grains, which are fertile upon pollination in vivo. It is reported here that isolated Antirrhinum majus microspores when cultured in an optimal medium develop to form mature, fertile pollen. Their development closely resembled that of pollen formed in vivo. Isolated microspores were bombarded with Aquorea victoria Green Fluorescent Protein (GFP), Discosoma Red Fluorescent Protein (dsRFP) and beta-glucuronidase (GUS) reporter genes under the control of various promoters and transient expression was observed throughout pollen development in vitro. Bombarded and not bombarded in vitro-matured pollen grains were able to germinate both in vitro and on receptive stigmas and to set seed. The protocol of maturation, transient transformation and germination of Antirrhinum majus pollen in vitro described here provides a valuable tool for basic and applied research.