The circuit assumes a p-channel depletion mode FET in that position, hence the p-channel JFET J177. The FET needs to be switched off during measurements and on when the sensor is idle, so its gate is basically a logic signal you control, LOW for on, HIGH for off.
MOSFETs are almost universally enhancement mode, not depletion mode, and the chances of sourcing a p-channel depletion mode MOSFET are slim.
Also the low voltages involve constrain which JFETs will be usable here, and I think you'll need to find a surface-mount equivalent to the J177 as this seems to be discontinued in through-hole (that's very common these days).
It might be easier to use a different circuit to short the sensor when idle, a reed-relay perhaps.
current input, voltage output. The feedback resistor VR1 maps the input current to a voltage.
A synthetic signal ground rail like this is commonly called a virtual ground, which is confusing as there's another meaning for virtual ground, being a node in the circuit kept at ground potential by negative feedback (but not connected to ground).
Call it signal ground perhaps?
The inverting input of the opamp is kept at virtual ground (in the second sense).