The Thistles, an important component in Scotland's 7s programme, are being piloted by National 7s coach Stephen Gemmell.
He said: "Saturday is a special day for Melrose, the birthplace of the sevens game. We are proud to be part of this celebration and it's important for us to look at players in another sevens environment with one eye to the final legs of the IRB World Series 7s in London and the Emirates Airline Edinburgh 7s at Murrayfield next month."
All ten members of the Thistles squad have played on the IRB circuit in the past. Forward Roddy Grant will face a late fitness test with Calum Forrester (GHA) a possible replacement.
The Thistles' first opponents will be the winner of the first-round tie between Langholm and Currie.
Scottish Thistles squad: Scott Forrest (Ayr)* CAPTAIN, Mike Adamson (Glasgow Warriors), Ben Addison (Stirling County)*, Roddy Grant (Heriot's)*, Chris Fusaro (Heriot's)**, Greig Laidlaw (Edinburgh), Colin Shaw (Glasgow Warriors), James Thompson (Heriot's)*, Richie Vernon (Glasgow Warriors), Ali Warnock (Edinburgh)
* = Member of Scottish Rugby's Senior National Academy
** = Member of Scottish Rugby's Junior National Academy and supported by Area Institute of Sport
Mathon Melrose Sevens draw (first tie 11.30am): First round - Langholm v Currie (winners play Scottish Thistles in round two); Dundee HSFP v Gala (winners play Roma in round two); Watsonians v West Of Scotland (winners play Ulster in round two); Peebles v Edinburgh Accies (winners play Gold Coast Breakers in round two); Kelso v Heriot's (winner v Leicester Tigers in round two); Jed-Forest v Hawick (winners v Chinese Agricultural University); Glasgow Hawks v Melrose (winners v Selkirk in round two); Ayr v Boroughmuir (winners v Shimlas in round two). The final is scheduled for approximately 6.20pm