Molecular aspects of viviparous reproductive biology of the tsetse fly (Glossina morsitans morsitans): Regulation of yolk and milk gland protein synthesis

Abstract

Tsetse fly (Diptera: Glossinidae) viviparous reproductive physiology remains to be explored at the molecular level. Adult females carry their young in utero for the duration of embryonic and larval development, all the while supplying their offspring with nutrients in the form of a "milk" substance secreted from a modified accessory gland. Flies give birth to fully developed third instar larvae that pupariate shortly after birth. Here, we describe the spatial and temporal expression dynamics of two reproduction-associated genes and their products synthesized during the first and second gonotrophic cycles. The proteins studied include a putative yolk protein, Glossina morsitans morsitans yolk protein 1 (GmmYP1) and the major protein found in tsetse "milk" secretions (Glossina morsitans morsitans milk gland protein, GmmMGP). Developmental stage and tissue-specific expression of GmmYP1 show its presence exclusively in the reproductive tract of the fly during oogenesis, suggesting that GmmYP1 acts as a vitellogenic protein. Transcripts for GmmMGP are present only in the milk gland tissue and increase in coordination with the process of larvigenesis. Similarly, GmmMGP can be detected at the onset of larvigenesis in the milk gland, and is present during the full duration of pregnancy. Expression of GmmMGP is restricted to the adult stage and is not detected in the immature developmental stages. These phenomena indicate that the protein is transferred from mother to larvae as nourishment during its development. These results demonstrate that both GmmYP1 and GmmMGP are involved in tsetse reproductive biology, the former associated with the process of oogenesis and the latter with larvigenesis.

“Wigglesworthia morsitans” Folate (Vitamin B 9 ) Biosynthesis Contributes to Tsetse Host Fitness

“…To examine whether chorismate pathway inhibition and the consequent suppression of downstream folate production influence intrauterine larval development, mated females were maintained on specific blood meal regimens (Fig. 5A) and the reproductive tracts were dissected at 20 days postemergence, a time point associated with late intrauterine larval development during the 1st gonotrophic cycle within mated WT females (65). The mean intrauterine area of the group maintained on 10 mM glyphosate-supplemented blood was significantly smaller than that of the mated controls ( Fig.…”

Sphingomyelinase Activity in Mother's Milk Is Essential for Juvenile Development: A Case from Lactating Tsetse Flies1

“…In tsetse (Glossina morsitans morsitans), lipid metabolism plays a major role in the reproductive cycle [13][14][15][16]. Tsetse reproduction is viviparous.…”

“…This is drastically different than most insects, which are oviparous, and deposit many eggs during each gonotrophic cycle. About 50% of the nutrients in the tsetse milk are lipids [13][14][15][16]. The evolution of viviparity has driven dramatic adaptations in the tsetse's reproductive physiology [17].…”

Vitamin B 6 Generated by Obligate Symbionts Is Critical for Maintaining Proline Homeostasis and Fecundity in Tsetse Flies

“…During each lactation cycle, the milk gland secretes up to 25 mg of milk that consists primarily of lipids and proteins (9). Twelve proteins have been identified as the major constituents of tsetse milk (10)(11)(12)(13). Lipids present in tsetse milk are generated either from metabolized blood meals or via lipolysis of stored fat body lipids (14)(15)(16)(17).…”