Elusive
My grandmother had a lovely pantry. It was a small room next to the kitchen, dedicated to the accumulation of 'non-perishables', i.e. mainly jam, rice, flour, sugar, dried potato, packets of biscuits and noodles. In some dark corner, you would invariably find a tin or two of powdered eggs or milk - a reminder of the days when fresh eggs and milk were hard to come by. My grandmother never really lost the habit of hoarding food, of storing the basics to provide sustenance to the family if needed. Cells, too, have their pantries. Germ cells, in particular. Plant germ cells have vacuoles. Birds' eggs have yolk. And mammalian oocytes have cytoplasmic lattices. All of which are used to bank nutrients for the embryonic development. Oocyte cytoplasmic lattices were discovered in the 1960s but we are only beginning to understand their molecular structure - and hence how they work. It seems, now, that cytoplasmic lattices are a place where maternal proteins accumulate to provide nutrients for developing embryos. Once thought to be composed of strings of ribosomes or keratin, we now know that cytoplasmic lattices consist of several components, one of which is a puzzling protein known as peptidyl arginine deiminase 6 or PADI6.
