Chromosomal sex determination in aphids controlled by juvenile hormone

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 107-109 ◽  
Author(s):  
Dinah F. Hales ◽  
Thomas E. Mittler
Keyword(s):  
Sex Determination ◽  
Juvenile Hormone ◽  
Key Words ◽  
Low Temperatures ◽  
High Titre ◽  
Corpus Allatum ◽  
Hormone Concentration ◽  
Hormone Analogue ◽  
X Chromosomes ◽  
Chromosomal Sex Determination

Parthenogenetically reproducing aphids give birth to males in response to low temperatures and short photoperiods. Since female aphids are XX and males are XO, the apomictic production of male eggs requires the elimination of one of the X chromosomes. Our previous experiments had suggested that male eggs were produced when the concentration of juvenile hormone was low; we now confirm this by showing that the juvenile hormone analogue kinoprene prevents ovulation of male eggs in aphids whose corpus allatum has been destroyed by precocene. Juvenile hormone concentration thus influences the behaviour of the X chromosomes during the maturation division of the eggs, a high titre resulting in the retention of both X chromosomes and a low titre in the elimination of one of them. Key words: sex determination, aphids, juvenile hormone, precocene, parthenogenesis.

Major sex-determining genes and the control of sexual dimorphism in Caenorhabditis elegans

Genome ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. 625-637 ◽  
Author(s):  
Jonathan Hodgkin ◽  
Andrew D. Chisholm ◽  
Michael M. Shen
Keyword(s):  
Caenorhabditis Elegans ◽  
Sex Determination ◽  
X Chromosome ◽  
Germ Line ◽  
Cell Lineage ◽  
Regulatory Genes ◽  
Nematode Caenorhabditis Elegans ◽  
X Chromosomes ◽  
The Many ◽  
Lineage Analysis

Sex determination in Caenorhabditis elegans involves a cascade of major regulatory genes connecting the primary sex determining signal, X chromosome dosage, to key switch genes, which in turn direct development along either male or female pathways. Animals with one X chromosome (XO) are male, while animals with two X chromosomes (XX) are hermaphrodite: hermaphrodite development occurs because the action of the regulatory genes is modified in the germ line so that both sperm and oocytes are made inside a completely female soma. The regulatory genes are being examined by both genetic and molecular means. We discuss how these major genes, in particular the last switch gene in the cascade, tra-1, might regulate the many different sex-specific events that occur during the development of the hermaphrodite and of the male.Key words: nematode, Caenorhabditis elegans, sex determination, sexual differentiation, cell lineage analysis.

scholarly journals Development and silk production by silkworm larvae after topical application of methoprene

2002 ◽  
Vol 59 (3) ◽  
pp. 585-588 ◽  
Author(s):  
José Ednilson Miranda ◽  
Sérgio Antonio de Bortoli ◽  
Roque Takahashi
Keyword(s):  
Juvenile Hormone ◽  
Larval Instar ◽  
Negative Effects ◽  
Hormone Analogue ◽  
Insect Growth Regulators ◽  
Silkworm Larvae ◽  
Silk Production ◽  
Juvenile Hormone Analogues ◽  
Chemical Products ◽  
Silkworm Bombyx Mori

Juvenile hormone analogues have been tested as insect growth regulators in silkworm (Bombyx mori), seeking an increment of silk production. These chemical products, when applied in small or moderate rates, promote the extension of the last larval instar. To understand the physiologic consequences on silk production by the silkworm strain C115 x N108, the application of methoprene, a juvenile hormone analogue, was performed to evaluate its effects on larval development and silk production. Methoprene was topically applied 48h after the fourth larval ecdysis, on the dorsal integument of the 2nd thoracic segment of the insects, at seven rates between 0 and 20 ng a.i. Methoprene influenced positively the duration of the fifth instar and the weight gain of the insects. The application of 1ng methoprene resulted in the heaviest silkglands, cocoons, shell cocoons and pupae weights. Comparatively to the control, the increment on silk production (approximately 24%) by the use of 1ng methoprene was more accentuated than the corresponding negative effects on the cocooning rate (approximately 12%).

Hormone Balance and the Control of Metamorphosis in Rhodnius Prolixus (Hemiptera)

1952 ◽  
Vol 29 (4) ◽  
pp. 620-631
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Juvenile Hormone ◽  
Corpus Allatum ◽  
Corpora Allata ◽  
Stage Larva ◽  
Mature Adults ◽  
Hormone Balance ◽  
Low Concentrations ◽  
Moulting Cycle ◽  
Increased Activity ◽  
Reduced Activity

A technique is described by which the intact larva of Rhodnius can be transfused with blood from another larva without interfering with ecdysis. If the 4th-stage larva receives blood from a 3rd-stage larva it develops characters little different from those of the 4th instar. This is attributed to the 3rd-stage larva producing juvenile hormone at a higher concentration. If the 4th-stage larva at 24 hr. after feeding receives blood from another 4th-stage larva at 8 days after feeding it develops characters intermediate between those of the 4th and 5th instars. This is attributed to the juvenile hormone being introduced too early in the moulting cycle. The hormone balance is upset by abnormal temperatures. The 4th-stage larva will not moult at a temperature of 36° C. although the larvae can survive up to about 40° C. At temperatures a little below 36° C. moulting is somewhat delayed and the characters developed are slightly ‘adultoid’ (prothetely). This is attributed to slightly reduced activity of the corpus allatum. At temperatures below 20° C. moulting is greatly delayed and the characters developed are slightly ‘juvenile’ (metathetely). This is attributed to relatively increased activity of the corpus allatum. Low concentrations of oxygen (less than 5 %) have an effect similar to that of high temperature. If 5th-stage larvae of Rhodnius receive implants of corpora allata from mature adults of Periplaneta they develop into 6th-stage larvae and many of these subsequently into 7th-stage larvae. The ‘juvenile hormone’ appears to be the same in the two insects. No evidence could be obtained for the persistence of juvenile hormone in the blood from one instar of Rhodnius to the next. The hypothesis of an active elimination of juvenile hormone by the corpus allatum at the time of metamorphosis remains therefore unproven.

Clues from other animals and theoretical considerations

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 3-4
Author(s):  
Anne McLaren
Keyword(s):  
Sex Determination ◽  
Genetic Control ◽  
Y Chromosome ◽  
X Chromosome ◽  
X Chromosomes ◽  
The Third ◽  
Mouse Species ◽  
Primary Male ◽  
Theoretical Considerations ◽  
State Of Activity

In the first two papers of this volume, the genetic control of sex determination in Caenorhabditis and Drosophila is reviewed by Hodgkin and by Nöthiger & Steinmarin-Zwicky, respectively. Sex determination in both cases depends on the ratio of X chromosomes to autosomes, which acts as a signal to a cascade of règulatory genes located either on autosomes or on the X chromosome. The state of activity of the last gene in the sequence determines phenotypic sex. In the third paper, Erickson & Tres describe the structure of the mouse Y chromosome and the polymorphisms that have been detected in different mouse species and strains. As in all mammals, the Y carries the primary male-determining locus; autosomal genes may also be involved in sex determination, but they must act down-stream from the Y-linked locus.

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