21 citations found
Insect Biochem Mol Biol 27 (1): 27-35 (1997)
Complete nucleotide sequence of the vitellogenin mRNA from the gypsy
moth: novel arrangement of the subunit encoding regions.
Hiremath S, Lehtoma K
USDA Forest Service Northeastern Forest Experiment Station, Delaware, OH
43015, USA.
Primary structure analysis and location of introns suggests evolutionary
relatedness among vitellogenin (Vg) genes from vertebrates and invertebrates,
including insects. We have determined the complete nucleotide sequence
of the gypsy moth VgmRNA, which shows that its structure is significantly
different from VgmRNAs in other systems. The nucleotide sequence was determined
using overlapping cDNA fragments generated from RACE reactions and rTh
polymerase-mediated PCR. The VgmRNA is 5579 nucleotides long and codes
for both the large and small subunits. However, the arrangement of the
subunit encoding regions in the gypsy moth VgmRNA is opposite of what has
been observed in other systems. Gypsy moth Vg gene is the first reported
example of a Vg gene where the 5'-terminal region codes for the large subunit
and the 3'-terminal region for the small subunit. Also, the sequence near
the junction of subunits was significantly different from those found in
other insects. This may be responsible for the relatively more stable precursor
of Vg subunits found in the gypsy moth hemolymph. It is not clear where
this divergence in the structure of Vg gene occurred during evolution,
since the Vg gene of another lepidopteran, Bombyx mori, conforms to the
structure of those in vertebrates and other invertebrates.
J Mol Evol 41 (4): 505-521 (1995)
Fundulus heteroclitus vitellogenin: the deduced primary structure of
a piscine precursor to noncrystalline, liquid-phase yolk protein.
LaFleur GJ Jr, Byrne BM, Kanungo J, Nelson LD, Greenberg RM, Wallace
RA
Whitney Laboratory, University of Florida, Marineland 32086, USA.
We have cloned and sequenced a cDNA encoding a vitellogenin (Vtg) from
the mummichog, Fundulus heteroclitus, an estuarine teleost. We constructed
a liver cDNA library against RNA from estrogen-treated male mummichogs.
Five overlapping cDNA clones totalling 5,197 bp were isolated through a
combination of degenerate oligonucleotide probing of the library and PCR.
The cDNA sequence contains a 5,112 bp open reading frame. The predicted
primary structure of the deduced 1,704-amino-acid protein is 30-40% identical
to other documented chordate Vtgs, establishing this Vtg as a member of
the ancient Vtg gene family. Of the previously reported chordate Vtg sequences
(Xenopus laevis, Gallus domesticus, Ichthyomyzon unicuspis, and Acipenser
transmontanus), all four act as precursor proteins to a yolk which is eventually
rendered insoluble under physiological conditions, either as crystalline
platelets or as noncrystalline granules. The yolk of F. heteroclitus, on
the other hand, remains in a soluble state throughout oocyte growth. The
putative F. heteroclitus Vtg contains a polyserine region with a relative
serine composition that is 10-20% higher than that observed for the other
Vtgs. The trinucleotide repeats encoding the characteristic polyserine
tracts of the phosvitin region follow a previously reported trend: TCX
codons on the 5' end and AGY codons toward the 3' end. Whether the difference
in Vtg primary structure between F. heteroclitus and that of other chordates
is responsible for the differences in yolk structure remains to be elucidated.
As the first complete teleost Vtg to be reported, these data will aid in
designing nucleotide and immunological probes for detecting Vtg as a reproductive
status indicator in F. heteroclitus and other piscine species.
J Mol Evol 34 (6): 478-492 (1992)
The boll weevil vitellogenin gene: nucleotide sequence, structure,
and evolutionary relationship to nematode and vertebrate vitellogenin genes.
Trewitt PM, Heilmann LJ, Degrugillier SS, Kumaran AK
Biology Department, Marquette University, Milwaukee, WI 53233.
Boll weevil (Anthonomus grandis) eggs contain two yolk proteins, YP47 and
YP160. Using anti-YP160 antiserum as probe, a partial-length complementary
DNA (cDNA) was isolated from a lambda gt11 adult female cDNA library. A
second partial-length cDNA was isolated from a lambda gt10 adult female
cDNA library by differential screening with male vs. female cDNAs. Northern
blot analysis showed that each cloned cDNA hybridized to a 6-kb female-specific
transcript. These cDNAs were used to probe a genomic library, and two overlapping
genomic clones were obtained that span the boll weevil vitellogenin gene.
The entire transcription unit was sequenced, and introns were mapped by
a combination of primer extension experiments, S1 nuclease protection experiments,
and polymerase chain reaction-mediated synthesis of two additional cDNA
clones. Based on these data, the vitellogenin mRNA is 5511 nucleotides
[plus a poly(A) tail of undetermined length] and specifies a provitellogenin
of 1790 amino acids. The deduced protein has a Glu+Gln content of 16.3%,
which is a relatively high value that is typical of most vitellogenins.
Protein sequence similarities including Cys clusters conserved between
boll weevil vitellogenin and Xenopus laevis A2 or Caenorhabditis elegans
vit-5 vitellogenins indicated that the boll weevil protein is a member
of the ancient nematode-vertebrate vitellogenin family. Moreover, the six
introns in the boll weevil vitellogenin gene interrupt the coding region
at positions closely or exactly corresponding to a subset of the positions
of the 34 vertebrate vitellogenin introns, further supporting the argument
for a common evolutionary relationship. This report represents the first
complete nucleotide sequence and structural analysis of a nondipteran insect
vitellogenin gene.
J Lipid Res 33 (6): 777-790 (1992)
Why is there sequence similarity between insect yolk proteins and vertebrate
lipases?
Bownes M
Institute of Cell and Molecular Biology, University of Edinburgh.
The major proteins stored in the yolk of developing oocytes are thought
to provide a nutritional store for utilization during embryogenesis. They
seem to fall into two major families of proteins. The first are called
vitellogenins and are found in frog, chicken, nematode, fish, and some
insects such as the boll weevil. The other group are called yolk proteins
and are found in dipteran insects such as fruitfly, housefly, fleshfly,
and blue-bottles. Both groups are the major proteins found in the oocyte
and are female-specific proteins endocytosed from the serum or hemolymph.
The yolk protein group were found to have sequence similarity to the triacylglycerol
lipases and lipoprotein lipases of vertebrates, including rat, pig, and
human. The yolk proteins do not have lipase activity, but the sequences
conserved between yolk proteins and lipases surround the active site where
there are interactions with lipids. The likely reason for the presence
of this domain in the yolk proteins is to bind a steroid hormone in a storage
form conjugated to lipids. This permits the storage of the hormone in an
inactive form until the yolk proteins are degraded, when it can be released
from its conjugate to induce developmental decisions in embryogenesis.
They may also transport lipids into the oocyte for use in embryogenesis.
Whilst the vitellogenin family of proteins do not share this homology with
the lipases they do have similarity to the human serum protein, apolipoprotein
B, which also has a role in binding lipids. These findings are discussed
in relation to the evolution and functions of lipases, apolipoproteins,
vitellogenins, and yolk proteins. Experiments aimed at isolating genes
encoding lipases in insects and at further elucidating the function of
the yolk proteins are suggested.
Genetics 127 (4): 769-780 (1991)
A cluster of vitellogenin genes in the Mediterranean fruit fly Ceratitis
capitata: sequence and structural conservation in dipteran yolk proteins
and their genes.
Rina M, Savakis C
Institute of Molecular Biology and Biotechnology, Foundation of Research
and Technology, Heraklion, Crete, Greece.
Four genes encoding the major egg yolk polypeptides of the Mediterranean
fruit fly Ceratitis capitata, vitellogenins 1 and 2 (VG1 and VG2), were
cloned, characterized and partially sequenced. The genes are located on
the same region of chromosome 5 and are organized in pairs, each encoding
the two polypeptides on opposite DNA strands. Restriction and nucleotide
sequence analysis indicate that the gene pairs have arisen from an ancestral
pair by a relatively recent duplication event. The transcribed part is
very similar to that of the Drosophila melanogaster yolk protein genes
Yp1, Yp2 and Yp3. The Vg1 genes have two introns at the same positions
as those in D. melanogaster Yp3; the Vg2 genes have only one of the introns,
as do D. melanogaster Yp1 and Yp2. Comparison of the five polypeptide sequences
shows extensive homology, with 27% of the residues being invariable. The
sequence similarity of the processed proteins extends in two regions separated
by a nonconserved region of varying size. Secondary structure predictions
suggest a highly conserved secondary structure pattern in the two regions,
which probably correspond to structural and functional domains. The carboxy-end
domain of the C. capitata proteins shows the same sequence similarities
with triacyglycerol lipases that have been reported previously for the
D. melanogaster yolk proteins. Analysis of codon usage shows significant
differences between D. melanogaster and C. capitata vitellogenins with
the latter exhibiting a less biased representation of synonymous codons.
Biochem Genet 28 (7-8): 415-432 (1990)
Vitellogenin protein diversity in the Hawaiian Drosophila.
Craddock EM, Kambysellis MP
Division of Natural Sciences, State University of New York, Purchase 10577.
Egg and female hemolymph proteins were resolved via SDS-polyacrylamide
gel electrophoresis in a diverse array of 33 endemic Hawaiian drosophilids,
encompassing 17 picture-winged species, 3 of the antopocerus species group,
9 fungus feeders, 1 species from each of the modified mouthparts, crassifemur
and ciliated tarsus groups, and 1 Scaptomyza species. Molecular weights
of the two (10 species) or three vitellogenin bands (22 species) were highly
variable, spanning a 7-kD range. The largest vitellogenin, V1, was the
most variable, showing a change of some 10% in its mean size of 47.6 kD.
The smallest V3 vitellogenin, mean size 44.1 kD, was evolutionarily the
most conservative in size. The species Drosophila hawaiiensis was found
to be polymorphic for two/three vitellogenin bands and, also, polymorphic
with respect to the size of the V1 protein. No inter- or intrapopulation
variability in vitellogenin size was detected in 10 other species examined.
The major features of vitellogenin protein evolution in the Hawaiian Drosophila
are change in molecular weight and regulatory differences that result in
quantitative differences between species in patterns of vitellogenin protein
production.
J Mol Evol 28 (6): 487-496 (1989)
Potential regulatory elements of nematode vitellogenin genes revealed
by interspecies sequence comparison.
Zucker-Aprison E, Blumenthal T
Department of Biology, Indiana University, Bloomington 47405.
The nematode, Caenorhabditis elegans, has a six-member gene family encoding
vitellogenins, the yolk protein precursors. These genes are expressed exclusively
in the intestine of the adult hermaphrodite. Here we report the cloning
of all five members of the homologous gene family from another Caenorhabditis
species, Caenorhabditis briggsae. Nucleotide sequence analysis of these
genes reveals they are about 85% identical to the C. elegans genes in the
coding regions. Overall similarity is much reduced in noncoding and flanking
regions. However, two repeated heptamers, previously identified in the
upstream regions of the C. elegans genes, are largely conserved in both
location and sequence in C. briggsae. Conservation of certain of these
heptamers suggests that proteins bound at these positions may be especially
important to promoter function and/or regulation. Comparative sequence
analysis also suggests the possibility that the first 70 bases of the vitellogenin
mRNAs can be folded into stable secondary structures. Almost all base differences
between the two species occur in sequences predicted to be unpaired, suggesting
that the ability to form intrastrand base pairs has been selected during
Caenorhabditis evolution.
Prog Biophys Mol Biol 53 (1): 33-69 (1989)
The evolution of egg yolk proteins.
Byrne BM, Gruber M, Ab G
Biochem J 255 (3): 1057-1060 (1988)
Is vitellogenin an ancestor of apolipoprotein B-100 of human low-density
lipoprotein and human lipoprotein lipase?
Baker ME
Department of Medicine, University of California, San Diego, La Jolla 92093.
Vitellogenin, an ancient animal protein, is the major yolk protein of eggs,
where it is used as a food source during embryogenesis. Here it is shown
that vitellogenins, including those from the invertebrates Caenorhabditis
elegans and Drosophila melanogaster, contain domains that are homologous
with parts of apolipoprotein B-100 (apoB-100) of human low-density lipoprotein
and human lipoprotein lipase. As vitellogenins are likely to have been
used by invertebrates during embryogenesis well before the circulation
of lipids appeared in vertebrates, it is suggested that copies of a precursor
gene, serving a function similar to vitellogenin, were modified to code
for part of apoB-100 and lipoprotein lipase in vertebrates. In addition
to providing a link between invertebrates and vertebrates for proteins
involved in lipid transport, these homologies suggest new functions for
vitellogenin other than being a yolk food for the developing embryo.
Trends Genet 4 (8): 227-232 (1988)
Evolution and expression of vitellogenin genes.
Wahli W
C R Acad Sci III 306 (14): 441-446 (1988)
Evolution of vitellins in the ovary and during development in three
species of Diptera, Drosophila melanogaster, Calliphora vicina and Prasarcophaga
argyrostoma
Karlinsky A, Mendes H, Schoeller-Raccaud J, Thomas-Orillard M
Laboratoire de Physiologie des Insectes, Universite Pierre-et-Marie-Curie,
Paris.
The SDS electrophoresis reveals the asynchronous appearance of the three
vitellins V1, V2, V3 during the ovarian cycle. It is always the V3 which
appears first with the beginning of previtellogenesis. The vitellin degradation
occurs late at the end of embryogenesis. The presence of a protein migrating
at the level of V3 during the whole development is discussed.
Nucleic Acids Res 15 (24): 10405-10417 (1987)
A single gene encoding vitellogenin in the sea urchin Strongylocentrotus
purpuratus: sequence at the 5' end.
Shyu AB, Blumenthal T, Raff RA
Institute for Molecular and Cellular Biology, Indiana University, Bloomington
47405.
The synthesis of vitellogenin (yolk protein precursor) in the sea urchin,
Strongylocentrotus purpuratus, is unique in that both males and females
produce a high level of the protein. In this paper we show that this organism
also is unique in possessing only a single vitellogenin gene. Like the
genes that encode analogous proteins in vertebrates, the sea urchin gene
is large, about 19 kb in length. The sequence surrounding the 5' end of
the gene revealed several other similarities to vertebrate vitellogenin
genes: the signal sequence is exceptionally short and has a sequence similar
to those from frog and chick; there is a canonical TATA box at -32; and
there is a sequence closely resembling the estrogen-responsive element
at -207.
J Biol Chem 262 (32): 15377-15385 (1987)
Comparison of the organization and fine structure of a chicken and
a Xenopus laevis vitellogenin gene.
Nardelli D, van het Schip FD, Gerber-Huber S, Haefliger JA, Gruber
M, Ab G, Wahli W
Institut de Biologie Animale, Universite de Lausanne, Switzerland.
The structural organization and the coding nucleotide sequence of the Xenopus
laevis A2 and the chicken major vitellogenin genes have been compared.
Both genes show the same exon-intron organization. However, the degree
of homology between the nucleotide and derived amino acid sequences varies
extensively along the genes. Several of the 35 exons are quite similar,
and a unique cysteine motif in the lipovitellin II domain is conserved
between the two genes. In contrast, one internal region is quite divergent.
Part of this region encodes phosvitin, which appears to have evolved rapidly
by both point mutations and duplications of serines or short other amino
acid stretches. On the basis of these observations, we discuss the possible
mechanism of evolution of phosvitin in vertebrates.
Biochemistry 26 (20): 6397-6402 (1987)
Vertebrate and nematode genes coding for yolk proteins are derived
from a common ancestor.
Nardelli D, Gerber-Huber S, van het Schip FD, Gruber M, Ab G, Wahli
W
Institut de Biologie animale, Universite de Lausanne, Switzerland.
One of the most obvious characteristics of the egg cells of oviparous animals
is their large size resulting to a major extent from the deposition of
nutritional reserves, mainly constituted of yolk proteins. In general,
these are derived from a precursor called vitellogenin, which undergoes
posttranslational modifications during secretion and during transport into
and storage within the oocytes. Comparative analysis of the structural
organization of the vitellogenin gene and of its product in different species
shows that the vitellogenin gene is very ancient and that in vertebrates
the gene may have more resemblance to the earliest gene than in invertebrates.
Cell 46 (7): 1053-1061 (1986)
An estrogen-responsive element derived from the 5' flanking region
of the Xenopus vitellogenin A2 gene functions in transfected human cells.
Klein-Hitpass L, Schorpp M, Wagner U, Ryffel GU
In the human breast cancer cell line MCF-7, we observe estrogen induction
of the stable transfected Xenopus vitellogenin A2 gene. An estrogen-responsive
element (ERE) could be defined by using a vitellogenin-chloramphenicol
acetyltransferase hybrid gene in transient transfection experiments. The
ERE is located in the 5' flanking region and is able to confer estrogen
inducibility to the thymidine kinase gene promoter. By 5' and 3' deletions
we have determined a 35 bp sequence sufficient for high stimulation by
estradiol. Even 18 bp give a small estrogen response. The 35 bp ERE contains
the palindromic sequence 5'GGTCACAGTGACC-3' as an essential element. The
fact that the ERE of a frog gene functions in human cells demonstrates
that signals and factors involved in the control have been conserved during
evolution.
Mol Cell Biol 5 (10): 2495-2501 (1985)
The Caenorhabditis elegans vitellogenin gene family includes a gene
encoding a distantly related protein.
Spieth J, Blumenthal T
While the nematode Caenorhabditis elegans is more primitive than most egg-laying
organisms, it's vitellogenins, or yolk protein precursors, appear to be
more complex. C. elegans oocytes accumulate two major classes of yolk proteins.
The first consists of two polypeptides with an Mr of about 170,000 (yp170A
and yp170B) encoded by a family of five closely related genes called vit-1
through vit-5. The second class consists of two smaller proteins with Mr
values of 115,000 (yp115) and 88,000 (yp88) which are cut from a single
precursor. Here we report the cloning and analysis of a single-copy gene
(vit-6) that encodes this precursor. The lengths of the gene and its mRNA
are about 5 X 10(3) base pairs. Like vit-1 through vit-5, vit-6 is expressed
exclusively in adult hermaphrodites. Comparison of portions of the coding
sequence indicates that vit-6 is distantly related to the vit-1 through
vit-5 gene family. Thus, even though the two classes of yolk proteins are
antigenically and physically distinct, they are encoded by a single highly
diverged gene family.
Comp Biochem Physiol [B] 82 (3): 497-505 (1985)
Vitellogenin genes and their products in closely and distantly related
species of Xenopus.
Baker BS, Steven J, Tata JR
Plasma vitellogenins from two closely related species of Xenopus, X. laevis
and X. borealis, and a more ancient species, X. tropicalis, exhibited the
same size on gel electrophoresis and were immunologically related. Partial
peptide maps of 125I-labelled plasma vitellogenins, however, revealed marked
differences in th structure and organisation of vitellogenin in the three
Xenopus species. Northern blot hybridisation of liver RNA from oestrogen-treated
males and females, probed with cloned vitellogenin cDNA, revealed the presence
of mRNA of the same size in the three species of Xenopus, which was absent
in untreated male liver. Cell-free translation of total liver RNA showed
the presence of functional mRNA coding for vitellogenin subunit of the
same size (Mr congruent to 210,000). Restriction endonuclease digestion
patterns of genomic DNA from the three Xenopus species, using cloned X.
laevis vitellogenin cDNA as the hybridisation probe, revealed significant
differences in the organisation of these genes, which occur at a higher
multiplicity in X. laevis and X. borealis than in X. tropicalis. Thus,
despite a high degree of conservation of size, overall sequence and immunological
identity of vitellogenin genes and their products in the three species
of Xenopus, there is a substantial structural rearrangement during evolution
of Xenopus within this multigene family.
Nucleic Acids Res 12 (22): 8595-8609 (1984)
Evolution of vitellogenin genes: comparative analysis of the nucleotide
sequences downstream of the transcription initiation site of four Xenopus
laevis and one chicken gene.
Germond JE, Walker P, ten Heggeler B, Brown-Luedi M, de Bony E, Wahli
W
Electron microscopic analysis of heteroduplexes between the most distantly
related Xenopus vitellogenin genes (A genes X B genes) has revealed the
distribution of homologous regions that have been preferentially conserved
after the duplication events that gave rise to the multigene family in
Xenopus laevis. DNA sequence analysis was limited to the region downstream
of the transcription initiation site of the Xenopus genes A1, B1 and B2
and a comparison with the Xenopus A2 and the major chicken vitellogenin
gene is presented. Within the coding regions of the first three exons,
nucleotide substitutions resulting in amino acid changes accumulate at
a rate similar to that observed in globin genes. This suggests that the
duplication event which led to the formation of the A and B ancestral genes
in Xenopus laevis occurred about 150 million years ago. Homologous exons
of the A1-A2 and B1-B2 gene pairs, which formed about 30 million years
ago, show a quite similar sequence divergence. In contrast, A1-A2 homologous
introns seem to have evolved much faster than their B1-B2 counterparts.
Ciba Found Symp 98: 96-110 (1983)
Hormonal regulation and expression of vitellogenin multigene family.
Tata JR, James TC, Watson CS, Williams JL, Wolffe AP
Yolk proteins are the most abundant egg proteins in oviparous animals.
They are deposited during oocyte maturation for use after fertilization
and are synthesized in the liver or fat body as a common precursor termed
vitellogenin. Hybridization with cloned DNA complementary to vitellogenin
messenger RNA has revealed a surprisingly high degree of evolutionary conservation
of sequence of vitellogenin genes among insects, amphibians and birds.
The synthesis of vitellogenin in vertebrates is directly under the control
of oestrogen at the level of gene transcription. In the frog, Xenopus,
vitellogenin genes occur as a multigene family, four of which are actively
expressed and are grouped as A and B genes. This multiplicity offers a
useful system for investigating the possible selective hormonal regulation
of expression of individual members of multigene families. When X. laevis
vitellogenin genes were activated by oestrogen in the liver of whole animals
or in cultures of parenchymal cells, the two groups of expressed genes
were not induced in an identical manner in cells from male and female animals.
The activation of A and B groups of genes was non-coordinate in male hepatocytes
and coordinate in female cells. Prior exposure of male hepatocytes to oestradiol
in vivo or in culture caused the pattern of expression to shift to that
in female cells. Since the X. laevis oocyte itself does not synthesize
vitellogenin in response to oestrogen, an attempt was made to activate
its dormant vitellogenin genes by transferring oestrogen-binding proteins
from the liver. Preliminary results show that the microinjection into the
oocyte of a preparation containing liver receptor-hormone complex led to
the synthesis of vitellogenin by the oocyte. Extension of these experiments
will not only enable a more precise analysis of the activation of the vitellogenin
multigene family to be made but will also provide direct functional evidence
for the role played by steroid hormone receptors in regulating gene expression.
J. Mol Evol 18 (6): 405-413 (1982)
An evolutionary model for the insect vitellins.
Harnish DG, White BN
Insects can be divided into three groups based on the sizes of the polypeptide
constituents of their vitellogenins and vitellins. In order to determine
the relationships between these groups, antisera to the vitellins of seven
insects from six taxonomic orders were used to assess immunological cross-reactivity.
Antigenic relatedness was observed only between vitellins from species
within the same family. Amino acid compositional data for vitellins from
nine species were used to assess homology by difference matrices. The S
delta Q values were similar for both intra-order and inter-order comparisons
and strongly suggested relatedness. The S delta n comparisons supported
the immunological data that indicated that the vitellins were evolving
rapidly. For most insect vitellins there are two distinct size classes
of polypeptides that seem to be derived from a single asymmetric proteolytic
cleavage of a precursor. We propose a model that suggests that the different
size polypeptides represent distinct domains and that in the evolution
of the vitellogenin genes of the Diptera and Hymenoptera there has been
domain elimination.
DNA 1 (4): 345-353 (1982)
Evolutionary conservation of vitellogenin genes.
James TC, Bond UM, Maack CA, Applebaum SW, Tata JR
Homologous and heterologous hybridizations in solution were performed between
sheared genomic DNA and DNA complementary to vitellogenin mRNA of Xenopus,
chicken, and migratory locust. The kinetics of hybridization and the thermal
stability of the hybrids formed suggested a high degree of conservation
of coding sequences of insect, amphibian, and avian vitellogenin genes.
These cDNA probes hybridized to calf thymus DNA to a slight, but significant,
extent, and not at all to Micrococcus lysodektikus DNA. DNA complementary
to Xenopus albumin mRNA did not cross-hybridize significantly with locust
or chicken DNA. Further evidence for the evolutionary conservation of vitellogenin
genes was obtained from Southern blot analysis of restriction endonuclease-digested
genomic DNA from a variety of vertebrate and invertebrate oviparous animals
(Xenopus, chicken, migratory and desert locusts, yellow meal worm, carab
moth, and Mediterranean fruitfly). When probed with cloned vitellogenin
cDNAs from Xenopus and migratory locust, the DNA of these organisms showed
varying degrees of homology of parts of the vitellogenin coding sequences.
Southern blot analysis also showed that a part of the sequence specified
in the cloned Xenopus vitellogenin cDNA was represented as repetitive DNA
in the locust genome. However, cloned locust vitellogenin cDNA hybridized
to discrete fragments of the restricted vertebrate DNA. These studies demonstrate
a remarkably high degree of conservation of insect, amphibian, and avian
vitellogenin genes.