A simple and inexpensive method for practical storage of field-sample proteins for subsequent MALDI-TOF MS analysis
Bibliographic record
Abstract
Protein-containing samples can readily be characterised and/or identified using matrix-assisted laser-desorption and ionisation time-of-flight mass spectrometry (MALDI-TOF MS). This technique however requires relatively-fresh biological material that contains proteins that have not yet undergone significant degradation. For field-work collection of samples, problems are often encountered due to delays between collection and sample processing, sample storage (possibly at elevated temperature and/or humidity in some climates), quarantine/regulatory restrictions on the transfer of living biological materials across national borders, and the potential to transfer unwanted microorganisms via non-living biological materials. In an attempt to overcome the above difficulties, we have developed a simple and inexpensive method for practical storage of field-sample proteins, for subsequent MALDI-TOF MS analysis, in which biological material is crushed onto filter paper and dried. The dried and protein-impregnated filter paper can then be soaked in an alcoholic solution suitable for the inactivation of microorganisms of concern and again dried for storage. After subsequent dry storage, the proteins may be eluted from the paper using a solution containing acetonitrile, trifluoroacetic acid, water, and MALDI-TOF MS matrix near to saturation. The extracted proteins are then pipetted onto the MALDI-TOF MS sample plate for subsequent analysis. Using this method, spectra of comparable quality to fresh-material controls have been obtained for acid-soluble proteins from Fallopia japonica and Impatiens glandulifera leaf material. Unlike untreated leaf material, high-quality spectra can be obtained with and without alcohol treatment even after storage for one month at up to 40 °C. We have developed a simple and inexpensive method for practical storage of field-sample proteins for subsequent MALDI-TOF MS analysis. Key benefits of this approach are a reduction in sample degradation, and consequent conservation of taxon-discriminatory spectral profiles, whilst minimising the potential for carryover of viable microorganisms.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.007 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".