Name: size matters: measurement of capsule diameter in cryptococcus neoformans
Uploaded: 2018-02-27T15:00:00
Description: Watch this Scientific Journal Video about Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans at JoVE.com

We thank the Molecular Biosciences (MOBI) doctoral program and the Biology Department at Middle Tennessee State University (MTSU) for providing the funding for this study. The project was also funded in part by a Special Projects grant awarded to D.E.N. by the MTSU Foundation.

NOTE: C. neoformans is a Biosafety Level 2 (BSL-2) pathogen and researchers working with it must take proper precautions. Detailed procedures on how to safely work with BSL-2 pathogens can be found on the Center for Disease Control&#39;s (CDC) website, but it is important to note that all persons coming into contact with C. neoformans should be properly trained in handling pathogenic agents and should always wear appropriate personal protective equipment (PPE), generally latex or nitrile gloves. Further...

<ol>
	<li>Park, B. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimation+of+the+current+global+burden+of+cryptococcal+meningitis+among+persons+living+with+HIV/AIDS.">Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDS.</a> AIDS. 23 (4), 525-530 (2009).</li><li>Coelho, C., Bocca, A. L., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+intracellular+life+of+Cryptococcus+neoformans.">The intracellular life of Cryptococcus neoformans.</a> Annu Rev Pathol. 9, 219-238 (2014).</li><li>Rajasingham, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+burden+of+disease+of+HIV-associated+cryptococcal+meningitis:+an+updated+analysis.">Global burden of disease of HIV-associated cryptococcal meningitis: an updated analysis.</a> Lancet Infect Dis. 17 (8), 873-881 (2017).</li><li>Limper, A. H., Adenis, A., Le, T., Harrison, T. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fungal+infections+in+HIV/AIDS.">Fungal infections in HIV/AIDS.</a> Lancet Infect Dis. 17 (11), e334-e343 (2017).</li><li>Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crisis+in+Infectious+Diseases:+2+Decades+Later.">Crisis in Infectious Diseases: 2 Decades Later.</a> Clin Infect Dis. 64 (7), 823-828 (2017).</li><li>McClelland, E. E. C., Eisenmann, A., H, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch+6.">Ch 6.</a> New Insights in Medical Mycology. , 131-157 (2007).</li><li>Leopold Wager, C. M., Wormley, F. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Classical+versus+alternative+macrophage+activation:+the+Ying+and+the+Yang+in+host+defense+against+pulmonary+fungal+infections.">Classical versus alternative macrophage activation: the Ying and the Yang in host defense against pulmonary fungal infections.</a> Mucosal Immunol. 7 (5), 1023-1035 (2014).</li><li>Kwon-Chung, K. J., Rhodes, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encapsulation+and+melanin+formation+as+indicators+of+virulence+in+Cryptococcus+neoformans.">Encapsulation and melanin formation as indicators of virulence in Cryptococcus neoformans.</a> Infect Immun. 51 (1), 218-223 (1986).</li><li>Vecchiarelli, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elucidating+the+immunological+function+of+the+Cryptococcus+neoformans+capsule.">Elucidating the immunological function of the Cryptococcus neoformans capsule.</a> Future Microbiol. 8 (9), 1107-1116 (2013).</li><li>Murphy, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+cryptococcal+antigens+on+cell-mediated+immunity.">Influence of cryptococcal antigens on cell-mediated immunity.</a> Rev Infect Dis. 10 Suppl 2, S432-S435 (1988).</li><li>Cherniak, R., Morris, L. C., Belay, T., Spitzer, E. D., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variation+in+the+structure+of+glucuronoxylomannan+in+isolates+from+patients+with+recurrent+cryptococcal+meningitis.">Variation in the structure of glucuronoxylomannan in isolates from patients with recurrent cryptococcal meningitis.</a> Infect Immun. 63 (5), 1899-1905 (1995).</li><li>Collins, H. L., Bancroft, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encapsulation+of+Cryptococcus+neoformans+impairs+antigen-specific+T-cell+responses.">Encapsulation of Cryptococcus neoformans impairs antigen-specific T-cell responses.</a> Infect Immun. 59 (11), 3883-3888 (1991).</li><li>Yasuoka, A., Kohno, S., Yamada, H., Kaku, M., Koga, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+molecular+sizes+of+Cryptococcus+neoformans+capsular+polysaccharide+on+phagocytosis.">Influence of molecular sizes of Cryptococcus neoformans capsular polysaccharide on phagocytosis.</a> Microbiol Immunol. 38 (11), 851-856 (1994).</li><li>Robertson, E. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryptococcus+neoformans+ex+vivo+capsule+size+is+associated+with+intracranial+pressure+and+host+immune+response+in+HIV-associated+cryptococcal+meningitis.">Cryptococcus neoformans ex vivo capsule size is associated with intracranial pressure and host immune response in HIV-associated cryptococcal meningitis.</a> J Infect Dis. 209 (1), 74-82 (2014).</li><li>Cordero, R. J., Bergman, A., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+behavior+of+capsule+enlargement+by+Cryptococcus+neoformans.">Temporal behavior of capsule enlargement by Cryptococcus neoformans.</a> Eukaryot Cell. 12 (10), 1383-1388 (2013).</li><li>O'Meara, T. R., Alspaugh, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Cryptococcus+neoformans+capsule:+a+sword+and+a+shield.">The Cryptococcus neoformans capsule: a sword and a shield.</a> Clin Microbiol Rev. 25 (3), 387-408 (2012).</li><li>McClelland, E. E., Smith, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gender+specific+differences+in+the+immune+response+to+infection.">Gender specific differences in the immune response to infection.</a> Archivum Immunologiae et Therapiae Experimentalis. 59 (3), (2011).</li><li>McClelland, E. E., Perrine, W. T., Potts, W. K., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+of+virulence+factor+expression+to+evolved+virulence+in+mouse-passaged+Cryptococcus+neoformans+lines.">Relationship of virulence factor expression to evolved virulence in mouse-passaged Cryptococcus neoformans lines.</a> Infect Immun. 73 (10), 7047-7050 (2005).</li><li>Zaragoza, O., Fries, B. C., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+capsule+growth+in+Cryptococcus+neoformans+by+mammalian+serum+and+CO(2).">Induction of capsule growth in Cryptococcus neoformans by mammalian serum and CO(2).</a> Infect Immun. 71 (1), 6155-6164 (2003).</li><li>Vartivarian, S. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+cryptococcal+capsular+polysaccharide+by+iron.">Regulation of cryptococcal capsular polysaccharide by iron.</a> J Infect Dis. 167 (1), 186-190 (1993).</li><li>McFadden, D. C., Fries, B. C., Wang, F., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capsule+structural+heterogeneity+and+antigenic+variation+in+Cryptococcus+neoformans.">Capsule structural heterogeneity and antigenic variation in Cryptococcus neoformans.</a> Eukaryot Cell. 6 (8), 1464-1473 (2007).</li><li>Garcia-Hermoso, D., Dromer, F., Janbon, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryptococcus+neoformans+capsule+structure+evolution+in+vitro+and+during+murine+infection.">Cryptococcus neoformans capsule structure evolution in vitro and during murine infection.</a> Infect Immun. 72 (6), 3359-3365 (2004).</li><li>Gates, M. A., Thorkildson, P., Kozel, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+architecture+of+the+Cryptococcus+neoformans+capsule.">Molecular architecture of the Cryptococcus neoformans capsule.</a> Mol Microbiol. 52 (1), 13-24 (2004).</li><li>Pontes, B., Frases, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Cryptococcus+neoformans+capsule:+lessons+from+the+use+of+optical+tweezers+and+other+biophysical+tools.">The Cryptococcus neoformans capsule: lessons from the use of optical tweezers and other biophysical tools.</a> Front Microbiol. 6, 640 (2015).</li><li>Shen, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+tracking+of+gene+expression+in+individual+cells+and+cell+compartments.">Automated tracking of gene expression in individual cells and cell compartments.</a> J R Soc Interface. 3 (11), 787-794 (2006).</li><li>Dorn, J. F., Danuser, G., Yang, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computational+processing+and+analysis+of+dynamic+fluorescence+image+data.">Computational processing and analysis of dynamic fluorescence image data.</a> Methods Cell Biol. 85, 497-538 (2008).</li><li>Nketia, T. A., Sailem, H., Rohde, G., Machiraju, R., Rittscher, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+live+cell+images:+Methods,+tools+and+opportunities.">Analysis of live cell images: Methods, tools and opportunities.</a> Methods. , 65-79 (2017).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biosafety in Microbiological and Biomedical Laboratories. , 33-38 (2015).</li><li>Kwon, O., Kang, S. T., Kim, S. H., Kim, Y. H., Shin, Y. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maximum+intensity+projection+using+bidirectional+compositing+with+block+skipping.">Maximum intensity projection using bidirectional compositing with block skipping.</a> J Xray Sci Technol. 23 (1), 33-44 (2015).</li><li>Janbon, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+the+genome+and+transcriptome+of+Cryptococcus+neoformans+var.+grubii+reveals+complex+RNA+expression+and+microevolution+leading+to+virulence+attenuation.">Analysis of the genome and transcriptome of Cryptococcus neoformans var. grubii reveals complex RNA expression and microevolution leading to virulence attenuation.</a> PLoS Genet. 10 (4), e1004261 (2014).</li><li>Bisson, G. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+HAART+is+associated+with+decreased+risk+of+death+during+initial+treatment+of+cryptococcal+meningitis+in+adults+in+Botswana.">The use of HAART is associated with decreased risk of death during initial treatment of cryptococcal meningitis in adults in Botswana.</a> J Acquir Immune Defic Syndr. 49 (2), 227-229 (2008).</li><li>van Teeffelen, S., Shaevitz, J. W., Gitai, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Image+analysis+in+fluorescence+microscopy:+bacterial+dynamics+as+a+case+study.">Image analysis in fluorescence microscopy: bacterial dynamics as a case study.</a> Bioessays. 34 (5), 427-436 (2012).</li><li>Granger, D. L., Perfect, J. R., Durack, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Virulence+of+Cryptococcus+neoformans.+Regulation+of+capsule+synthesis+by+carbon+dioxide.">Virulence of Cryptococcus neoformans. Regulation of capsule synthesis by carbon dioxide.</a> J Clin Invest. 76 (2), 508-516 (1985).</li></ol>

For decades, the capsule has been a major focus of research for both mycologists and clinicians interested in C. neoformans and cryptococcosis due to its role as a major virulence factor for the pathogen. Using microscopy to measure differences in capsule size between strains and under different growth conditions can provide important information about the pathogen and its responses to various stimuli (i.e., different environmental conditions, potential drug treatments, etc.) Here, we have outl...

Affecting a quarter million people every year and resulting in more than 180,000 deaths annually, Cryptococcus neoformans is a pathogenic, intracellular yeast and the causative agent of cryptococcosis1,2,3. Hardest hit are HIV-positive patients in poor countries who do not have ready access to antiretroviral therapy, making them acutely susceptible to the illness4,5,6. Data from the CDC indicate that in sub-Saharan Africa, C. neoformans kills more people than tuberculosis annually and more every month than any Ebola outbreak on record1. The most common route of exposure occurs from inhaling desiccated spores that are commonplace in the environment7. Upon entering the lungs, there are several virulence factors that contribute to the success of C. neoformans within infected individuals. The polysaccharide capsule is considered the microbe&#39;s primary virulence factor, as acapsular strains are not virulent8.
The cryptococcal capsule is made of up three principle components: glucuronoxylomannan (GXM), galactoxylomannan (GalXM), and mannoproteins (MPs)9. While MPs are a relatively minor cell wall-associated component of the capsule, they are immunogenic and can promote a mostly pro-inflammatory response9,10. In contrast, GXM and GalXM make up the bulk of the capsule (&#62;90% by weight) and have immunosuppressive effects11. In addition to its immunomodulatory effects, the rapid enlargement of the capsule in vivo creates a mechanical barrier to ingestion by host phagocytic cells (i.e., neutrophils and macrophages)12. The C. neoformans capsule and its synthesis are complex, but overall, increased capsule diameter is correlated with increased virulence6,13,14. Given this, it is important for C. neoformans researchers to be able to quickly and accurately quantify capsule measurements.
Both the C. neoformans cell and its polysaccharide capsule are dynamic structures and show changes over time15. The capsule can change in density, size, and assembly in response to changes in the host environment16,17,18. Low iron or nutrient levels, exposure to serum, the human physiological pH, and increased CO2 are known to initiate capsule growth16,18,19,20. Further, researchers have shown structural changes resulting in significant differences in immunoreactivity during an infection, lending an advantage to C. neoformans over its host21,22. This is known because the architecture of the C. neoformans capsule has been analyzed in a variety of ways. Electron microscopy, for example, has revealed that the capsule has a heterogeneous matrix with an inner electron-dense layer underneath an outer, more permeable layer23. Light scattering and the use of optical tweezers have allowed researchers to further elucidate its macromolecular properties24. Analyzing the results from both static and dynamic light scattering measurements, we know that the polysaccharide capsule has a complex branching structure23. Optical tweezers have been used to test the rigidity of the structure as well as evaluate its antibody reactivity24. However, by far the most frequently employed analysis of the C. neoformans capsule is the measurement of its size.
To quantify capsule size, researchers use what should be a simple measurement: the linear diameter of the capsule. Digital microscopes are used to capture images of multiple C. neoformans cells (generally hundreds) stained with either India ink or fluorescent dyes. The size of each cell body and surrounding capsule is measured. The data are compiled, and the average diameter of the capsule is calculated by subtracting the cell body diameter from the whole cell diameter (cell body + capsule). Up until this point, these measurements have been done manually. While generally accurate, this method has drawbacks for researchers. Large data sets can take days or even weeks to analyze by hand. And because these measurements are done manually, subjectivity and human error may affect the result.
Automated computational image analysis has become an indispensable tool for researchers in many areas of molecular cell biology, enabling faster and more reliable analysis of biological images 25,26,27. Precise image analysis techniques are necessary to mine quantitative information from what are often complex and immense data sets. However, some measurements, especially the measurement of C. neoformans capsule, have been difficult to automate. Accurately identifying the interface between the cell wall and capsule, which generally appears as a dark ring when imaged by phase-contrast microscopy, can be troublesome to resolve using a simple threshold. Further, C. neoformans cells in culture tend to clump together and accurate segmentation of the cells is necessary for accurate measurements.
The aim of this project was to (i) illustrate one of the standard protocols for capsule induction in C. neoformans, (ii) compare and contrast India ink and fluorescence staining as they pertain to capsule diameter measurements, (iii) develop simple, computational methods to measure capsule diameter using images of India ink stained cells using an image analysis software, and, (iv) assess the benefits and limitations of measuring capsule diameter manually and using software automation. We find that of the two staining methods, fluorescent labeling of the cell wall and capsule, while more time-consuming, provided the most consistent results between experiments. However, both methods enabled us to successfully distinguish between lab and clinical C. neoformans strains exhibiting different capsule sizes. Further, we were able to automate the measurement of capsule diameter from India ink stained images and found that this was a viable alternative to manual measurement of capsule.

<table border="0" cellpadding="0" cellspacing="0" width="983">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:451px;">Capsule Induction</td>
			<td style="width:204px;"></td>
			<td style="width:117px;"></td>
			<td style="width:211px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C. neoformans cells</td>
			<td></td>
			<td></td>
			<td>The clinical lab strain, H99S, was a kind gift from Dr. John Perfect (Duke University).&#160; The clinical strains, B18 and B52, were kind gifts from Dr. Greg Bisson (University of Pennsylania).&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Yeast Peptone Dextrose Broth (YPD)</td>
			<td>Fisher Scientific</td>
			<td>DF0428-17-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate Buffered Saline (PBS)</td>
			<td></td>
			<td></td>
			<td>This is made in the lab using standard recipe (137mM NaCl, 2.7 mM KCl, 10mM Na2HPO4O, 2 mM Kh2PO4O)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM/high-glucose with L-glutamine, without sodium pyruvate</td>
			<td>GE Life Sciences</td>
			<td>SH30022.01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6-well plates</td>
			<td>Falcon</td>
			<td>CL5335-5EA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Shaking incubator</td>
			<td>Thermo Scientific&#160;</td>
			<td></td>
			<td>MaxQ6000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CO2 incubator</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td>Isotemp</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td>Legend XTR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Staining</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microcentrifuge</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td>Legend Micro 21R</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">India ink</td>
			<td>Fisher Scientific</td>
			<td>14-910-56</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Calcofluor white</td>
			<td>Sigma-Aldrich</td>
			<td>18909-100ML-F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">18B7 mouse anti-GXM antibody conjugated to Alexafluor 488</td>
			<td></td>
			<td></td>
			<td>A kind gift from Dr. Arturo Casadevall (Johns Hopkins University)&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS with 1% Bovine Serum Albumin (BSA)</td>
			<td></td>
			<td></td>
			<td>PBS is the same recipe listed above (line 4) with 1% BSA added and filter sterilized.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine Serum Albumin</td>
			<td>Sigma-Aldrich</td>
			<td>A9418</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Superfrost microscope slides</td>
			<td>Fisher Scientific</td>
			<td>12-550-143</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glass coverslips</td>
			<td>Corning</td>
			<td>2855-18</td>
			<td>#1.5 thickness</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Clear nail polish or other non-toxic sealant</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Image Acquisition&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Immersion oil</td>
			<td>Cargille&#160;</td>
			<td>16484</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Light microscope with immersion oil objective</td>
			<td>Zeiss</td>
			<td></td>
			<td>Zeiss Axio A1 with a Plan - NEOFLUAR 100x oil immersion NA 1.30 objective</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Light microscope camera</td>
			<td>Zeiss</td>
			<td></td>
			<td>Zeiss Axiocam ErCD camera</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Confocal microscope with oil immersion objective</td>
			<td>Zeiss</td>
			<td></td>
			<td>LSM 700 laser scanning confocal equipped with a Plan-Apochromat 63X NA 1.4 oil immersion DIC M27 objective.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Confocal microscope software</td>
			<td>Zen 2009</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Confocal microscope camera</td>
			<td>Nikon</td>
			<td></td>
			<td>Nikon Ti-Eclipse with a Intensilight epifluorescence illuminator (Nikon), CoolSNAP MYO microscope camera (Photometrics), Plan Apo 60x NA 1.40 oil immersion objective (Nikon) and 1.5x magnification changer.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Widefield imaging software</td>
			<td>Nikon Elements (Nikon)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Capsule Measurement</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Image editing software</td>
			<td>Photoshop (Adobe)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microscope software for manual measurement</td>
			<td>Axiovision (Carl Zeiss)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Image analysis software for automated meesurement</td>
			<td>Aivia (DRVision Technologies)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spreadsheet software</td>
			<td>Excel (Microsoft)</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

size matters: measurement of capsule diameter in cryptococcus neoformans

The polysaccharide capsule of Cryptococcus neoformans is the primary virulence factor and one of the most commonly studied aspects of this pathogenic yeast. Capsule size can vary widely between strains, has the ability to grow rapidly when introduced to stressful or low nutrient conditions, and has been positively correlated with strain virulence. For these reasons, the size of the capsule is of great interest to C. neoformans researchers. The growth of the C. neoformans capsule is induced during phenotypic testing to help understand the effects of different treatments on the yeast or size differences between strains. Here we describe one of the standard methods of capsule induction and compare two accepted methods of staining and measuring capsule diameter: (i) India ink, a negative stain, used in conjunction with conventional light microscopy and (ii) co-staining with fluorescent dyes of both the cell wall and capsule followed by confocal microscopy. Finally, we show how measurement of capsule diameter from India ink-stained samples can be automated using computational image analysis.

To illustrate capsule induction, cell staining, imaging, and measuring techniques, we used three strains of C. neoformans: the common, well-characterized laboratory strain, H99S30, and two clinically isolated strains of previously unknown capsule diameter, B18 and B5231.
The workflow of capsule induction, staining, and image acquisition using India ink is shown in <strong ...

Watch this Scientific Journal Video about Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans at JoVE.com

Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans

The polysaccharide capsule is the primary virulence factor in Cryptococcus neoformans, and its size correlates with strain virulence. Capsule diameter measurements are used in phenotypic testing and to gauge therapeutic efficacy. Here a standard method of capsule induction is presented, and two methods of staining and measuring diameter are compared.

Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans

The polysaccharide capsule of Cryptococcus neoformans is the primary virulence factor and one of the most commonly studied aspects of this pathogenic ...

Research

JoVE Journal

Immunology and Infection

Measurement of Cytosolic Ca2+ in Isolated Contractile Lymphatics

Measurement of Cytosolic Ca2+ in Isolated Contractile Lymphatics

Lymphatic vessels comprise a multifunctional transport system that maintains fluid homeostasis, delivers lipids to the central circulation, and acts as a ...

Measurement of &#947;HV68 Infection in Mice

Measurement of ÃƒÅ½Ã‚Â³HV68 Infection in Mice

&gamma;-Herpesviruses (&gamma;-HVs) are notable for their ability to establish latent infections of lymphoid cells1. The narrow host range of human ...

Quantitative Measurement of the Immune Response and Sleep in Drosophila

Quantitative Measurement of the Immune Response and Sleep in Drosophila

A complex interaction between the immune response and  host behavior has been described in a wide range of species. Excess sleep, in  particular, is known ...

Measurement of Tactile Allodynia in a Murine Model of Bacterial Prostatitis

Uropathogenic Escherichia coli (UPEC) are pathogens that play an important role in urinary tract infections and bacterial prostatitis1. We have recently ...

Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy

Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy

Many aspects of the infection of macrophages by Cryptococcus neoformans have been extensively studied and well defined. However, one particular ...

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans

Cryptococcosis is a life-threatening infection caused by pathogenic fungi of the genus Cryptococcus. Infection occurs upon inhalation of spores, which are ...

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans

The basidiomycete Cryptococcus neoformans, an invasive opportunistic pathogen of the central nervous system, is the most frequent cause of fungal ...

Measurement of In Vitro Integration Activity of HIV-1 Preintegration Complexes

Measurement of In Vitro Integration Activity of HIV-1 Preintegration Complexes

HIV-1 envelope proteins engage cognate receptors on the target cell surface, which leads to viral-cell membrane fusion followed by the release of the ...

Automated Measurement of Cryptococcal Species Polysaccharide Capsule and Cell Body

Automated Measurement of Cryptococcal Species Polysaccharide Capsule and Cell Body

The purpose of this technique is to provide a consistent, accurate, and manageable process for large numbers of polysaccharide capsule measurements.
...

A Method for the Measurement of Salivary Gland Function in Mice

Patients with Sj&#246;gren&#39;s syndrome, an autoimmune disease affecting the exocrine glands, develop salivary gland inflammation and have reduced ...