BACKGROUND
the nucleotide sequences from numerous animal genomes have been derived and include examples from both vertebrate and invertebrate organisms.
in addition, determination of the genomic sequences of many more organisms are in progress, yielding a broad picture of the diversity and common pathways among differing organisms.
genome sequences for the insects apis mellifera , anopheles gambiae , drosophila melanogaster , and bombyx mori  have been reported  <cit> , and additional insect genome sequences including acyrthosiphon pisum , aedes aegypti and culex pipiens , several drosophila species, nasonia vitripennis , rhodnius prolixus , and tribolium castaneum  are anticipated.
in addition, a number of est databases derived from lepidoptera are available .
the lepidoptera  are the second largest order of the class insecta.
as such, they are a diverse group of insects distributed worldwide and throughout different climates ranging from that in siberia to the tropics.
thus, it is important to compare the genomes of a number of species within the order and to that of other insects.
lepidoptera are viewed as being among the most beautiful insects, yet their larvae are major pests to economically important crops and forests.
among the lepidoptera, the silkworm, b. mori, has been studied intensively, since it is a commercially important insect.
in addition, the lepidoptera are valued as models to examine insect-plant and insect-pathogen interactions.
their study and comparative genomic analyses will render valuable tools for insect pest management and the improvement of widely used lepidopteran pathogens, the baculoviruses, as foreign gene expression vectors.
in this study, we report the establishment of an expressed sequence tag  database of  <dig>  unique sequences from the cell line iplb-sf- <dig>   <cit> , a cell line derived from immature ovaries of pupae of the fall armyworm, spodoptera frugiperda.
this and other est databases can serve as the starting point from which other s. frugiperda genome clones can be surveyed or to explore gene expression profiles using microarray assays.
more importantly, these and additional ests can be the basis for comparative genomic analyses among lepidoptera or other genomes within the insecta.
RESULTS
general sequence survey
to start characterizing sf- <dig> sequences, two independent directionally cloned cdna libraries that had been previously constructed for use in yeast two-hybrid screens using the plasmid vectors pb42ad and pyes <dig>  were utilized.
initially, about  <dig> clones were partially sequenced from each library to assess library quality.
both libraries yielded acceptable results.
the library cloned in pyes <dig> was selected for further sequencing.
in all, a total of  <dig>  cloned inserts were subjected to single-pass sequencing from their 5' ends,  <dig> clones in the vector pb42ad and  <dig>  clones in the vector pyes <dig>  the  <dig>  sequences were trimmed of vector sequences, poly a/t tails, low quality, adaptor, and contaminating bacterial sequences, and screened for a minimum length of  <dig> bp.
this resulted in a total of  <dig>  high quality ests with an average length of  <dig> bases .
no attempt was made to carry out sequencing to saturation.
these ests were assembled using the cap <dig>  <cit>  program and verified using the phrap  <cit>  program.
both programs assemble overlapping ests to commence forming contigs.
a total of  <dig>  ests were assembled into  <dig> contigs, leaving  <dig> sequences as singlets.
contigs and singlets together resulted in  <dig>  unique sequences that putatively represent different transcripts.
the number of ests in the  <dig> contigs varied from  <dig> to 63; 56% of contig sequences had two ests, 10% had three ests, and 10% had greater than  <dig> ests .
the average length of the assembled contigs was  <dig> bases; longer than the average length of singlets .
the longest contig sequence, contig  <dig>  was  <dig>  bases.
highly redundant genes
a total of  <dig> contigs containing  <dig> ests were highly redundant.
this accounted for more than 13% of the total high quality ests.
the minimum number of ests that made up these most highly redundant contigs was  <dig> .
distribution of ests in each contig can be accessed via the estmd database  <cit>  using the contig viewer search function.
the best matched genes of  <dig> contigs, totaling  <dig> ests, are from s. frugiperda, verifying the source of the cdnas.
nearly half  of the highly redundant contigs, totaling  <dig> ests, had significant homology to various ribosomal proteins, indicating high transcript abundance of ribosomal protein genes, as expected.
four contigs totaling  <dig> ests had matches similar to sequences derived from mitochondrial cytochrome b or cytochrome oxidase subunits .
the most redundant contig was composed of  <dig> ests and had significant homology to nadh dehydrogenase subunit - <dig>  from s. frugiperda  <cit> .
comparative sequence analysis of s. frugiperda cdna data
we used the  <dig>  unique ests to search non-redundant protein databases using blastx .
a total of  <dig> sequences  matched known proteins at a cut-off expectation -value of 10- <dig> or below.
eleven sequences  had hits with e-values at e < 10- <dig>   <dig> sequences  had hits with e-values between 10- <dig> and 10- <dig>   <dig> sequences  had hits with e-values between 10- <dig> and 10- <dig>   <dig> sequences  had hits with e-values between 10- <dig> and 10- <dig>  and  <dig> sequences  had hits with e-values between 10- <dig> and 10- <dig>  the main matched e-value, between 10- <dig> and 10- <dig>  included  <dig> searched unique sequences, which was more than 70% of the  <dig> matched sequences.
the remainder of the unique sequences  had no meaningful matches .
given that drosophila is the most thoroughly annotated insect genome  <cit> , we compared s. frugiperda unique sequences with drosophila genes using blastx.
a total of  <dig> sequences had hits with drosophila genes at e < 10- <dig>  that is,  <dig> % of the  <dig>  unique sequences .
a subset of  <dig> unique sequences  matched to drosophila genes with the cut-off equal to e < 10- <dig>  a total of  <dig> sequences  had matches with drosophila genes between 10- <dig> and 10- <dig>   <dig> sequences  had matches between e-values of 10- <dig> and 10- <dig>  and  <dig> sequences  had matches between e-values of 10- <dig> and 10- <dig>
we compared our unique sequences from the sf- <dig> cell line with ests obtained from another s. frugiperda-derived cell line, sf <dig>  <cit> , using blastn  <cit> .
a total of  <dig> sequences  matched the ests from sf <dig> cells with an e-value equal to  <dig> .
a total of  <dig> sequences  were similar but not exact matches with ests from sf <dig> with e-values >  <dig> and < 10- <dig>  in addition, almost half of our ests  had no significant match with the sf <dig> ests.
therefore,  <dig> of our sequences  were not previously reported in the sf <dig> est project.
we also compared our sequences with about  <dig>  s. frugiperda midgut-specific ests available in ncbi dbest database using blastn.
only  <dig> sequences  matched with e-value equal to  <dig> .
the remaining sequences matched midgut ests to different extents:  <dig> sequences  had e-values between  <dig> and 10- <dig>   <dig> sequences  had e-values of 10- <dig> and 10- <dig>   <dig> sequences  had e-values of 10- <dig> and 10- <dig>   <dig> sequences  had e-values of 10- <dig> and 10- <dig>  and  <dig> sequences  had e-values of 10- <dig> and 10- <dig>  a total of  <dig> sequences  had no hits with the available midgut ests.
in addition, we compared our unique sequences with those of the silkworm b. mori.
we used blastn to search the all b. mori est sequences available using a blast search site  <cit> , given that the genome sequence is not fully annotated.
a total of  <dig> from the  <dig>  unique sequences  had hits with silkworm sequences at e < 10- <dig> .
of these,  <dig> unique ests  had e-values between 10- <dig> and 10- <dig>  a total of  <dig> sequences  had no matches with silkworm sequences.
conserved s. frugiperda and drosophila gene sequences
we found  <dig> highly conserved sequences between s. frugiperda and drosophila genes based on blastx analyses.
all of the  <dig> sequences were from contigs, with one, contig  <dig>  having an e-value of 10- <dig>  six sequences had matches with their homologous drosophila genes at an e-value of  <dig>
we chose contig  <dig> for phylogenetic analysis given it was the most conserved sequence between spodoptera and drosophila.
the sequences from heat shock  <dig> cognate  <dig> proteins were aligned with clustalw and only similar sequences with complete coding sequences  were included in the alignment as described in methods.
alignments of the heat shock protein  <dig> cognate  <dig>  with similar ones in the class insecta  showed that the heat shock protein  <dig> cognate  <dig> of s. frugiperda formed a single clade with trichoplusia ni, manduca sexta, bombyx mori, and lonomia oblique, as expected since all these organisms belong to the order lepidoptera.
this clade shares a common ancestor with members of other orders, diptera, orthoptera, and hymenoptera, and with insects in other clades .
functional classification of s. frugiperda ests
gene ontology  has been widely used to characterize gene function annotation and classification  <cit> .
go describes gene function using controlled vocabulary and hierarchy including molecular function, biological processes, and cellular communication.
in this report, we used well annotated go information of drosophila melanogaster to interpret the gene function of our ests.
each unique sequence from s. frugiperda was assigned the same gene function of the best blastx hit  with drosophila sequences based on the annotated go of drosophila  <cit> .
this method has been successfully used to annotate bee brain est function  <cit> .
the major go categories for the unique sequences included those outlining gene molecular function , biological processes , and cellular components .
the highest final child go term for molecular function was the hydrogen transporting two-sector atpase in the nucleotide binding category.
the highest final go term for biological processes was protein biosynthesis, under the protein metabolism and biosynthesis categories, which had  <dig> unique sequences accounting for 7% of the total unique sequences matched in this category.
the largest number for a final go term in cellular components was cytosolic large ribosomal subunit under both the ribosome and cytosol categories.
seventy-eight unique sequences belonged to this go term, which accounted for  <dig> % of the total unique sequences annotated for cellular components.
we found  <dig> unique sequences  showing significant similarity with drosophila signal transduction factors .
among these,  <dig> sequences belonged to the receptor binding category and the remaining  <dig> sequences belonged to receptor and receptor signaling proteins.
based on go, we also found one sequence for an apoptosis-related gene, pyes2-ct_017_g <dig> p1ca, which showed similarity to the dros ophila aac <dig> gene.
two additional sequences, pb42ad-1_001_f <dig> pb <dig> primer and pyes2-ct_010_g <dig> p1ca, showed significant similarity to drosophila gnbp <dig>  a gene involved in defense and immunity.
pathway analysis based on the kyoto encyclopedia of genes and genomes  classification
kegg has been widely used for pathway mapping  <cit> .
enzyme commission  numbers were used to judge which sequences pertained to a specific pathway.
twenty-nine unique sequences including  <dig> contigs and  <dig> singlets accounted for  <dig> % of unique sequences and matched enzymes with an ec number.
within these  <dig> sequences,  <dig> unique sequences  containing  <dig> contigs and  <dig> singlets were mapped to kegg biochemical pathways .
genes involved in amino acid metabolism had the highest mapping sequences  and  <dig> mappings.
genes involved in carbohydrate metabolism included  <dig> sequences and  <dig> mappings.
other genes included those involved in nucleotide metabolism , translation , energy metabolism , lipid metabolism , and metabolism of other amino acids .
contigs  <dig> and  <dig> each had  <dig> mappings to different pathways under a different metabolism category, which was the highest number for a single sequence.
contig  <dig>  contig  <dig>  pyes2-ct_008_e <dig> p1ca, and pyes2-ct_012_c <dig> p1ca mapped to two pathways.
the remaining pathway-assigned sequences only mapped to one pathway.
est database
to efficiently manage and retrieve information in the ests analyzed in this project, we developed an est model database   <cit> .
the est model database is a highly efficient, web-accessible, user-friendly relational database.
it provides several tools to search raw, cleaned, and assembled est sequences, genes and go, as well as pathway information.
the user may input and submit keywords or ids to the server using the web interface.
ests and annotated function data are in the relational database and results are sent back to the user in proper formats in response to a query.
it also provides a clear contig view and blast searches, data submission, and download pages.
in both the go and kegg pathway search pages, estmd allows users to search go and pathways not only by single gene name, symbol, or id, but also by using a file that contains a batch of sequence ids or flybase ids.
all the sequence function classification based on go and kegg pathway in this study was done using estmd.
the file search provision in estmd allows users to obtain information regarding the possible function of many ests or genes at one time instead of searching them individually .
discussion
single-pass sequencing was performed on  <dig>  cdna clones derived from two sf- <dig> cdna libraries.
using this sequence data, we have established an est database comprised of  <dig>  unique sequences from the sf- <dig> cell line, derived from the lepidopteran insect s. frugiperda.
a total of  <dig> unique sequences  had homology to sequences found in drosophila.
these sequences will be useful for comparative genomics within and outside the lepidoptera, establishing microarrays, and as probes to either clone or down-regulate genes of interest by rna interference in order to perform studies related to spodoptera, other closely related lepidoptera, or their pathogens.
this is one of two published annotated est studies available for s. frugiperda.
a prior report included a similar scale project as that reported here with  <dig>  ests of which  <dig>  were unique sequences obtained from a clonally-derived cell line of sf- <dig>  sf <dig>  <cit> .
the majority of unique sequences in the previous study consisted of the highly abundant ribosomal protein genes and these were found to have low codon usage bias  <cit> .
our data provides  <dig> novel s. frugiperda sequences.
a small percentage of our sequences  had similarities, whether these reflect cell line specific differences is not clear at this time.
together these two studies and other available s. frugiperda ests constitute seminal work on the genome sequence of s. frugiperda.
the sequences reported in this study have been made available for incorporation into spodobase  <cit> .
many insects within the lepidoptera, including the fall armyworm s. frugiperda , are pests that cause significant annual damage to a number of field crops and tree foliage worldwide.
deciphering their genomic sequences will aid in developing improved pest control agents, such as baculoviruses and polydnaviruses/parasitic wasps.
although these pathogens are being used or sought as biological control agents, there remains ample room for improvement of their entomopathogenic properties.
finally, molecular tools have been used in the study of lepidoptera or have been derived from lepidoptera.
the transposable element piggybac was discovered in the lepidopteran t. ni  and has been used to create somatic and germline transformations in a number of organisms including crickets, butterflies, plasmodium falciparum, and more recently, mice  <cit> .
lepidoptera are also amenable to down-regulation of genes by rna interference and transgenic techniques  <cit> .
thus, knowledge of the genomics of lepidoptera will aid in their manipulation or use as molecular tools.
CONCLUSIONS
we have established an est database from the s. frugiperda-derived cell line sf- <dig>  containing  <dig>  unique sequences.
lepidoptera are among the most diverse insects and as such, sequences and est databases from various genomes will be instrumental in assessing species-specific genes, phylogeny, and parallels within species of the same order.
in addition, comparative analyses with available genomes of other insects including a. mellifera, d. melanogaster, a. gambiae, ae.
aegypti, and t. castaneum will yield additional insights since these include members of distinct orders , providing a more accurate picture of the conserved pathways and the order-specific gene elements in the insecta.

 the nucleotide sequences from numerous animal genomes have been derived and include examples from both vertebrate and invertebrate organisms. in addition, determination of the genomic sequences of many more organisms are in progress, yielding a broad picture of the diversity and common pathways among differing organisms. genome sequences for the insects apis mellifera, anopheles gambiae, drosophila melanogaster, and bombyx mori have been reported, and additional insect genome sequences including acyrthosiphon pisum, aedes aegypti and culex pipiens, several drosophila species, nasonia vitripennis, rhodnius prolixus, and tribolium castaneum are anticipated. in addition, a number of est databases derived from lepidoptera are available. the lepidoptera are the second largest order of the class insecta. as such, they are a diverse group of insects distributed worldwide and throughout different climates ranging from that in siberia to the tropics. thus, it is important to compare the genomes of a number of species within the order and to that of other insects. lepidoptera are viewed as being among the most beautiful insects, yet their larvae are major pests to economically important crops and forests. among the lepidoptera, the silkworm, b. mori, has been studied intensively, since it is a commercially important insect. in addition, the lepidoptera are valued as models to examine insect-plant and insect-pathogen interactions. their study and comparative genomic analyses will render valuable tools for insect pest management and the improvement of widely used lepidopteran pathogens, the baculoviruses, as foreign gene expression vectors. in this study, we report the establishment of an expressed sequence tag database of unique sequences from the cell line iplb-sf-, a cell line derived from immature ovaries of pupae of the fall armyworm, spodoptera frugiperda. this and other est databases can serve as the starting point from which other s. frugiperda genome clones can be surveyed or to explore gene expression profiles using microarray assays. more importantly, these and additional ests can be the basis for comparative genomic analyses among lepidoptera or other genomes within the insecta.  general sequence survey to start characterizing sf- sequences, two independent directionally cloned cdna libraries that had been previously constructed for use in yeast two-hybrid screens using the plasmid vectors pb42ad and pyes were utilized. initially, about clones were partially sequenced from each library to assess library quality. both libraries yielded acceptable results. the library cloned in pyes was selected for further sequencing. in all, a total of cloned inserts were subjected to single-pass sequencing from their 5' ends, clones in the vector pb42ad and clones in the vector pyes the sequences were trimmed of vector sequences, poly a/t tails, low quality, adaptor, and contaminating bacterial sequences, and screened for a minimum length of bp. this resulted in a total of high quality ests with an average length of bases. no attempt was made to carry out sequencing to saturation. these ests were assembled using the cap program and verified using the phrap program. both programs assemble overlapping ests to commence forming contigs. a total of ests were assembled into contigs, leaving sequences as singlets. contigs and singlets together resulted in unique sequences that putatively represent different transcripts. the number of ests in the contigs varied from to 63; 56% of contig sequences had two ests, 10% had three ests, and 10% had greater than ests. the average length of the assembled contigs was bases; longer than the average length of singlets. the longest contig sequence, contig was bases. highly redundant genes a total of contigs containing ests were highly redundant. this accounted for more than 13% of the total high quality ests. the minimum number of ests that made up these most highly redundant contigs was. distribution of ests in each contig can be accessed via the estmd database using the contig viewer search function. the best matched genes of contigs, totaling ests, are from s. frugiperda, verifying the source of the cdnas. nearly half of the highly redundant contigs, totaling ests, had significant homology to various ribosomal proteins, indicating high transcript abundance of ribosomal protein genes, as expected. four contigs totaling ests had matches similar to sequences derived from mitochondrial cytochrome b or cytochrome oxidase subunits. the most redundant contig was composed of ests and had significant homology to nadh dehydrogenase subunit - from s. frugiperda. comparative sequence analysis of s. frugiperda cdna data we used the unique ests to search non-redundant protein databases using blastx. a total of sequences matched known proteins at a cut-off expectation -value of 10- or below. eleven sequences had hits with e-values at e < 10- sequences had hits with e-values between 10- and 10- sequences had hits with e-values between 10- and 10- sequences had hits with e-values between 10- and 10- and sequences had hits with e-values between 10- and 10- the main matched e-value, between 10- and 10- included searched unique sequences, which was more than 70% of the matched sequences. the remainder of the unique sequences had no meaningful matches. given that drosophila is the most thoroughly annotated insect genome, we compared s. frugiperda unique sequences with drosophila genes using blastx. a total of sequences had hits with drosophila genes at e < 10- that is, % of the unique sequences. a subset of unique sequences matched to drosophila genes with the cut-off equal to e < 10- a total of sequences had matches with drosophila genes between 10- and 10- sequences had matches between e-values of 10- and 10- and sequences had matches between e-values of 10- and 10- we compared our unique sequences from the sf- cell line with ests obtained from another s. frugiperda-derived cell line, sf, using blastn. a total of sequences matched the ests from sf cells with an e-value equal to. a total of sequences were similar but not exact matches with ests from sf with e-values > and < 10- in addition, almost half of our ests had no significant match with the sf ests. therefore, of our sequences were not previously reported in the sf est project. we also compared our sequences with about s. frugiperda midgut-specific ests available in ncbi dbest database using blastn. only sequences matched with e-value equal to. the remaining sequences matched midgut ests to different extents: sequences had e-values between and 10- sequences had e-values of 10- and 10- sequences had e-values of 10- and 10- sequences had e-values of 10- and 10- and sequences had e-values of 10- and 10- a total of sequences had no hits with the available midgut ests. in addition, we compared our unique sequences with those of the silkworm b. mori. we used blastn to search the all b. mori est sequences available using a blast search site, given that the genome sequence is not fully annotated. a total of from the unique sequences had hits with silkworm sequences at e < 10-. of these, unique ests had e-values between 10- and 10- a total of sequences had no matches with silkworm sequences. conserved s. frugiperda and drosophila gene sequences we found highly conserved sequences between s. frugiperda and drosophila genes based on blastx analyses. all of the sequences were from contigs, with one, contig having an e-value of 10- six sequences had matches with their homologous drosophila genes at an e-value of we chose contig for phylogenetic analysis given it was the most conserved sequence between spodoptera and drosophila. the sequences from heat shock cognate proteins were aligned with clustalw and only similar sequences with complete coding sequences were included in the alignment as described in methods. alignments of the heat shock protein cognate with similar ones in the class insecta showed that the heat shock protein cognate of s. frugiperda formed a single clade with trichoplusia ni, manduca sexta, bombyx mori, and lonomia oblique, as expected since all these organisms belong to the order lepidoptera. this clade shares a common ancestor with members of other orders, diptera, orthoptera, and hymenoptera, and with insects in other clades. functional classification of s. frugiperda ests gene ontology has been widely used to characterize gene function annotation and classification. go describes gene function using controlled vocabulary and hierarchy including molecular function, biological processes, and cellular communication. in this report, we used well annotated go information of drosophila melanogaster to interpret the gene function of our ests. each unique sequence from s. frugiperda was assigned the same gene function of the best blastx hit with drosophila sequences based on the annotated go of drosophila. this method has been successfully used to annotate bee brain est function. the major go categories for the unique sequences included those outlining gene molecular function, biological processes, and cellular components. the highest final child go term for molecular function was the hydrogen transporting two-sector atpase in the nucleotide binding category. the highest final go term for biological processes was protein biosynthesis, under the protein metabolism and biosynthesis categories, which had unique sequences accounting for 7% of the total unique sequences matched in this category. the largest number for a final go term in cellular components was cytosolic large ribosomal subunit under both the ribosome and cytosol categories. seventy-eight unique sequences belonged to this go term, which accounted for % of the total unique sequences annotated for cellular components. we found unique sequences showing significant similarity with drosophila signal transduction factors. among these, sequences belonged to the receptor binding category and the remaining sequences belonged to receptor and receptor signaling proteins. based on go, we also found one sequence for an apoptosis-related gene, pyes2-ct_017_g p1ca, which showed similarity to the dros ophila aac gene. two additional sequences, pb42ad-1_001_f pb primer and pyes2-ct_010_g p1ca, showed significant similarity to drosophila gnbp a gene involved in defense and immunity. pathway analysis based on the kyoto encyclopedia of genes and genomes classification kegg has been widely used for pathway mapping. enzyme commission numbers were used to judge which sequences pertained to a specific pathway. twenty-nine unique sequences including contigs and singlets accounted for % of unique sequences and matched enzymes with an ec number. within these sequences, unique sequences containing contigs and singlets were mapped to kegg biochemical pathways. genes involved in amino acid metabolism had the highest mapping sequences and mappings. genes involved in carbohydrate metabolism included sequences and mappings. other genes included those involved in nucleotide metabolism, translation, energy metabolism, lipid metabolism, and metabolism of other amino acids. contigs and each had mappings to different pathways under a different metabolism category, which was the highest number for a single sequence. contig contig pyes2-ct_008_e p1ca, and pyes2-ct_012_c p1ca mapped to two pathways. the remaining pathway-assigned sequences only mapped to one pathway. est database to efficiently manage and retrieve information in the ests analyzed in this project, we developed an est model database. the est model database is a highly efficient, web-accessible, user-friendly relational database. it provides several tools to search raw, cleaned, and assembled est sequences, genes and go, as well as pathway information. the user may input and submit keywords or ids to the server using the web interface. ests and annotated function data are in the relational database and results are sent back to the user in proper formats in response to a query. it also provides a clear contig view and blast searches, data submission, and download pages. in both the go and kegg pathway search pages, estmd allows users to search go and pathways not only by single gene name, symbol, or id, but also by using a file that contains a batch of sequence ids or flybase ids. all the sequence function classification based on go and kegg pathway in this study was done using estmd. the file search provision in estmd allows users to obtain information regarding the possible function of many ests or genes at one time instead of searching them individually. discussion single-pass sequencing was performed on cdna clones derived from two sf- cdna libraries. using this sequence data, we have established an est database comprised of unique sequences from the sf- cell line, derived from the lepidopteran insect s. frugiperda. a total of unique sequences had homology to sequences found in drosophila. these sequences will be useful for comparative genomics within and outside the lepidoptera, establishing microarrays, and as probes to either clone or down-regulate genes of interest by rna interference in order to perform studies related to spodoptera, other closely related lepidoptera, or their pathogens. this is one of two published annotated est studies available for s. frugiperda. a prior report included a similar scale project as that reported here with ests of which were unique sequences obtained from a clonally-derived cell line of sf- sf. the majority of unique sequences in the previous study consisted of the highly abundant ribosomal protein genes and these were found to have low codon usage bias. our data provides novel s. frugiperda sequences. a small percentage of our sequences had similarities, whether these reflect cell line specific differences is not clear at this time. together these two studies and other available s. frugiperda ests constitute seminal work on the genome sequence of s. frugiperda. the sequences reported in this study have been made available for incorporation into spodobase. many insects within the lepidoptera, including the fall armyworm s. frugiperda, are pests that cause significant annual damage to a number of field crops and tree foliage worldwide. deciphering their genomic sequences will aid in developing improved pest control agents, such as baculoviruses and polydnaviruses/parasitic wasps. although these pathogens are being used or sought as biological control agents, there remains ample room for improvement of their entomopathogenic properties. finally, molecular tools have been used in the study of lepidoptera or have been derived from lepidoptera. the transposable element piggybac was discovered in the lepidopteran t. ni and has been used to create somatic and germline transformations in a number of organisms including crickets, butterflies, plasmodium falciparum, and more recently, mice. lepidoptera are also amenable to down-regulation of genes by rna interference and transgenic techniques. thus, knowledge of the genomics of lepidoptera will aid in their manipulation or use as molecular tools.  we have established an est database from the s. frugiperda-derived cell line sf- containing unique sequences. lepidoptera are among the most diverse insects and as such, sequences and est databases from various genomes will be instrumental in assessing species-specific genes, phylogeny, and parallels within species of the same order. in addition, comparative analyses with available genomes of other insects including a. mellifera, d. melanogaster, a. gambiae, ae. aegypti, and t. castaneum will yield additional insights since these include members of distinct orders, providing a more accurate picture of the conserved pathways and the order-specific gene elements in the insecta. 
we have constructed an est database using two cdna libraries from the s. frugiperda-derived cell line, sf- the database consists of ests which were assembled into contigs and singlets for a total of unique sequences. in addition, cell lines derived from spodoptera frugiperda and other lepidopteran insects are routinely used for baculovirus foreign gene expression. this study reports the results of an expressed sequence tag sequencing project in cells from the lepidopteran insect s. frugiperda, the fall armyworm. little is known about the genome sequences of lepidopteran insects, although this group of insects has been studied extensively in the fields of endocrinology, development, immunity, and pathogen-host interactions. s. frugiperda is an agriculturally important pest insect and genomic information will be instrumental for establishing initial transcriptional profiling and gene function studies, and for obtaining information about genes manipulated during infections by insect pathogens such as baculoviruses.
 little is known about the genome sequences of lepidopteran insects, although this group of insects has been studied extensively in the fields of endocrinology, development, immunity, and pathogen-host interactions. in addition, cell lines derived from spodoptera frugiperda and other lepidopteran insects are routinely used for baculovirus foreign gene expression. this study reports the results of an expressed sequence tag sequencing project in cells from the lepidopteran insect s. frugiperda, the fall armyworm.  we have constructed an est database using two cdna libraries from the s. frugiperda-derived cell line, sf- the database consists of ests which were assembled into contigs and singlets for a total of unique sequences.  s. frugiperda is an agriculturally important pest insect and genomic information will be instrumental for establishing initial transcriptional profiling and gene function studies, and for obtaining information about genes manipulated during infections by insect pathogens such as baculoviruses. 