Q. metagenome에서 dark matter가 무엇인가?
A. Dark matter in metagenomics refers to genetic material that cannot be classified into any known taxonomic groups. Metagenomics is the study of genetic material obtained directly from environmental samples, such as soil, water, and human microbiomes.
In metagenomic sequencing, researchers can generate large amounts of DNA sequences from a sample, but not all of these sequences can be identified to a specific taxonomic group, as they do not match any known organisms in databases. These unclassified sequences are referred to as "dark matter" because they represent a significant portion of the genetic material in a sample but their origin and function are unknown.
Dark matter in metagenomics can be caused by several factors, including sequencing errors, incomplete databases, and the presence of novel and undiscovered organisms. As researchers continue to develop new methods for analyzing metagenomic data, they are discovering new ways to identify and characterize dark matter, which may ultimately provide new insights into the diversity and function of microbial communities in different environments.
너무나 많은 서열들이 unclassified 된 것을 말함. 이는 sequencing errors일 수도 있고, incomplete databases때문일 수도 있으며 혹은 새롭거나 밝혀지지 않았던 유기체에서 비롯된 것일수도 있음.
Q. 시퀀싱에서 batch effec가 무엇인가?
A. Batch effect in sequencing refers to systematic technical variations that arise during sample processing and sequencing, which can lead to biases and confounding effects in downstream analyses.
In sequencing experiments, batches of samples are often processed together to increase efficiency and reduce cost. However, even with careful experimental design and quality control, there can be subtle differences in sample handling, processing, or sequencing that can introduce batch effects. These effects can manifest as differences in gene expression, methylation patterns, or other molecular features between batches of samples, which are not related to the biological differences between the samples of interest.
Batch effects can be caused by various factors, such as differences in sample preparation protocols, reagent lots, sequencing runs, and sequencing platforms. To minimize batch effects, researchers can use various strategies, such as randomizing samples across batches, including replicate samples in each batch, and normalizing data using statistical methods that adjust for batch effects. Additionally, careful quality control and monitoring during sample processing and sequencing can help detect and correct for batch effects before downstream analysis.
batch effect는 분석에 영향을 미치거나 편향을 만들수 있는 시퀀싱의 기술적인 문제이다. 시퀀싱은 종종 비용 절약과 효율성을 위해 여러 샘플을 한번에 돌린다. 그러나 아주 조심스러운 기술자와 퀄리티 검수에도 각 샘플에서 미묘한 처리의 차이가 발생할 수 있다.
batch effect은 여러 원인에 의해 발생한다. 예를들어 샘플의 준비 프로토콜의 차이나, 시약의 양, 시퀀싱 run, 시퀀싱 플랫폼(기계)가 있다.
batch effect를 줄이기 위해서는, 연구자는 다양한 전략을 구상해야 한다. 예를들어 각 배치마다 샘플을 랜덤하게 놓고나, 각 배치에 여러 반복 샘플을 놓거나, batch effect에 대한 통계적 후처리를 사용한다.
Q.현재 마이크로바이옴 연구의 한계점은?
A. Microbiome research has made tremendous progress in recent years, but it still has some limitations. One of the main limitations is the difficulty in accurately characterizing and interpreting the complex and dynamic microbial communities that make up the microbiome.
Here are some specific limitations of microbiome research:
- Lack of standardization: There is currently no standardized protocol for sample collection, storage, and processing, which can lead to inconsistencies and biases in the data.
- Limited understanding of functional implications: While researchers have identified many different microbial taxa in the microbiome, the functional implications of these taxa are not well understood. We still need to better understand how these microbial communities interact with each other and with their host.
- Limited knowledge of host-microbiome interactions: We still have a limited understanding of the interactions between the microbiome and the host, and how these interactions contribute to health and disease.
- Difficulty in analyzing large datasets: Microbiome research generates large amounts of complex data that require sophisticated computational and statistical methods for analysis, which can be challenging and time-consuming.
- Limited diversity in study populations: Most microbiome research has been conducted on Western populations, limiting our understanding of the diversity and variability of the microbiome across different ethnic and geographic groups.
To address these limitations, future microbiome research will need to focus on developing standardized protocols for sample collection and processing, integrating multi-omics data to better understand the functional implications of the microbiome, and expanding research to include more diverse populations and ecological niches.
Q.현재 메타게놈 shotgun 연구의 한계점은?
A. Some of the main limitations of metagenome shotgun sequencing research are as follows:
- Limits in assessing microbial diversity: Shotgun sequencing of metagenomes can detect all microbial taxa present in a sample, but some microbial clusters may be difficult to detect if the sequencing depth is not sufficient. Additionally, some microbial clusters may be missed entirely, as they may have a low abundance or their DNA may not be captured efficiently during the sequencing process.
- Incomplete reference databases: Metagenome shotgun sequencing relies on comparisons to existing reference databases to identify microbial taxa and functions. However, these databases are often incomplete, biased, and may not represent the full diversity of microbial life, especially for non-model organisms or environments.
- Difficulty in assigning functions to genes: Metagenome shotgun sequencing can provide a vast amount of genetic information, but assigning functions to genes can be challenging. Many genes in metagenomes have no known function or annotation, making it difficult to interpret their biological significance.
- Technical artifacts and batch effects: Metagenome shotgun sequencing is subject to various technical artifacts and batch effects, which can introduce biases and confounding factors in downstream analyses. These effects can arise from differences in sequencing platforms, library preparation methods, and other experimental factors.
- High computational demands: Shotgun sequencing generates large amounts of data that require sophisticated bioinformatics tools and computational resources for processing, analysis, and interpretation. This can make metagenome shotgun sequencing prohibitively expensive and time-consuming for some research questions and applications.
