= Silvia G. Acinas
{c}
<Silvia G. Acinas> is a researcher in marine <microbial ecology>, <genomics> and <evolution>. Her institutional research profile describes work connecting the genetic diversity of marine <microorganisms> with their ecological capabilities, using approaches including <metagenomics> and cultivation.<Silvia G. Acinas research profile at ICM-CSIC>[Research biography, marine microbial diversity and genomic approaches]{ref}
Acinas was first author of a 2004 study of variation among <16S ribosomal RNA> sequences encoded within individual <genomes>. A <genome> can contain multiple copies of a <16S ribosomal RNA gene>; those copies can be identical or differ in sequence. The study compared copy numbers, sequence divergence and redundancy. These properties complicate the interpretation of diversity estimates based on the marker.<Divergence and redundancy of 16S rRNA sequences in genomes with multiple rrn operons by Silvia G. Acinas and others>[Abstract; Figures 1–2, copy counts and identical sequences within genomes]{ref}
An invented example separates two effects. Suppose three microbial <cells> each have two marker-gene copies and two other cells each have five. With one complete <genome> per cell and no other biases, there are $3\times2+2\times5=16$ marker copies among five cells. Their contributions to the copy pool are $6/16$ and $10/16$, whereas their contributions to cell number are $3/5$ and $2/5$. Marker abundance and cell abundance have different denominators. If copies within a single genome also differ in sequence, multiple sequence variants can originate from one organism.
This work illustrates a recurring measurement issue in <microbial ecology>: a molecular marker is a biological object whose own variation affects the inference. Acinas and colleagues investigated that variation directly, rather than simply equating each recovered sequence with a separate kind of microorganism.<Divergence and redundancy of 16S rRNA sequences in genomes with multiple rrn operons by Silvia G. Acinas and others>[Abstract, intragenomic divergence and implications for diversity estimation]{ref}
\Image[https://emm.icm.csic.es/silvia-g.-acinas/avatar_hu10669823330226872856.jpg]
{title=Silvia G. Acinas}
{description=Portrait identified by the ICM-CSIC Ecology of Marine Microbes research profile: https://emm.icm.csic.es/silvia-g.-acinas/ .}
{height=300}
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