Metamorphosis and denucleation of the brain in the miniature wasp Megaphragma viggianii (Hymenoptera: Trichogrammatidae). (September 2022)

• Record Type: Journal Article
• Authors: Makarova, Anastasia A.; Veko, Egor N.; Polilov, Alexey A.
• Is Part Of: Arthropod structure & development. Volume 70(2022)
• Publication Date: 2022-09
• Subjects: Development -- Pupa -- Brain -- Megaphragma -- Miniaturization -- Lysis; Arthropoda -- Morphology -- Periodicals; Arthropoda -- Anatomy -- Periodicals; Arthropoda -- Cytology -- Periodicals; Arthropods -- growth & development -- Periodicals; 595
• DOI: 10.1016/j.asd.2022.101200
• Languages: English
• ISSNs: 1467-8039

Abstract

Abstract: Holometabolan brains undergo structural and allometric changes and complex reorganizations during metamorphosis. In minute egg parasitoids, brain formation is shifted to the late larva and young pupa, due to extreme de-embryonization. The brains of Megaphragma wasps undergo denucleation, the details of which remained unknown. We describe the morphological and volumetric changes in the brain of Megaphragma viggianii (Trichogrammatidae) during pupal development with emphasis on the lysis of nuclei and show that the absolute and relative volume of the brain decrease by a factor of 5 from prepupa to adult at the expense of the cell body rind. The first foci of lysis appear during early pupal development, but most nuclei (up to 97%) are lost between pharate adult and adult. The first signs of lysis (destruction of the nuclear envelopes) occur in pupae with red eyes. The number of lysis foci (organelle destruction and increasing number of lysosomes and degree of chromatin compaction) strongly increases in pupae with black eyes. The cell body rind volume strongly decreases during pupal development (in larger insects it increases slightly or remains unchanged). Elucidation of the lysis of nuclei in neurons and of the functioning of an anucleate brain is an important objective for neuroscience. Highlights: Brain development of Megaphragma viggianii during the pupal stage is described. About 97% nuclei in M. viggianii brain cells are lysed at the pharate adult phase. Neuropil volume in M. viggianii brain remains unchanged during pupal development.