Gene duplication in an African cichlid adaptive radiation.

BACKGROUND: Gene duplication is a source of evolutionary innovation and can contribute to the divergence of lineages; however, the relative importance of this process remains to be determined. The explosive divergence of the African cichlid adaptive radiations provides both a model for studying the general role of gene duplication in the divergence of lineages and also an exciting foray into the identification of genomic features that underlie the dramatic phenotypic and ecological diversification in this particular lineage. We present the first genome-wide study of gene duplication in African cichlid fishes, identifying gene duplicates in three species belonging to the Lake Malawi adaptive radiation (Metriaclima estherae, Protomelas similis, Rhamphochromis "chilingali") and one closely related species from a non-radiated riverine lineage (Astatotilapia tweddlei). RESULTS: Using Astatotilapia burtoni as reference, microarray comparative genomic hybridization analysis of 5689 genes reveals 134 duplicated genes among the four cichlid species tested. Between 51 and 55 genes were identified as duplicated in each of the three species from the Lake Malawi radiation, representing a 38%-49% increase in number of duplicated genes relative to the non-radiated lineage (37 genes). Duplicated genes include several that are involved in immune response, ATP metabolism and detoxification. CONCLUSIONS: These results contribute to our understanding of the abundance and type of gene duplicates present in cichlid fish lineages. The duplicated genes identified in this study provide candidates for the analysis of functional relevance with regard to phenotype and divergence. Comparative sequence analysis of gene duplicates can address the role of positive selection and adaptive evolution by gene duplication, while further study across the phylogenetic range of cichlid radiations (and more generally in other adaptive radiations) will determine whether the patterns of gene duplication seen in this study consistently accompany rapid radiation.

Sexual and social stimuli elicit rapid and contrasting genomic responses.

Sensory physiology has been shown to influence female mate choice, yet little is known about the mechanisms within the brain that regulate this critical behaviour. Here we examine preference behaviour of 58 female swordtails, Xiphophorus nigrensis, in four different social environments (attractive and unattractive males, females only, non-attractive males only and asocial conditions) followed by neural gene expression profiling. We used a brain-specific cDNA microarray to identify patterns of genomic response and candidate genes, followed by quantitative PCR (qPCR) examination of gene expression with variation in behaviour. Our microarray results revealed patterns of genomic response differing more between classes of social stimuli than between presence versus absence of stimuli. We identified suites of genes showing diametrically opposed patterns of expression: genes that are turned 'on' while females interact with attractive males are turned 'off' when interacting with other females, and vice versa. Our qPCR results identified significant predictive relationships between five candidate genes and specific mate choice behaviours (preference and receptivity) across females exposed to males, with no significant patterns identified in female or asocial conditions or with overall locomotor activity. The identification of stimulus- and behaviour-specific responses opens an exciting window into the molecular pathways associated with social behaviour and mechanisms that underlie sexual selection.

The utility of ultrasonographically guided large-core needle biopsy: results from 500 consecutive breast biopsies.

Five hundred ultrasonographically guided large-core needle breast biopsies of solid masses were performed in 446 women. Histopathologic results were correlated with imaging findings. Ultrasonographically guided large-core needle biopsy resulted in diagnosis of malignancy (n = 124) or severe atypical ductal hyperplasia (n = 4) in 128 lesions (26%). In the remaining 372 lesions (74%), ultrasonographically guided large-core needle biopsy yielded benign pathologic results. Follow-up of more than 1 year (n = 225), results of surgical excision (n = 50), or both were obtainable in 275 (74%) of the benign lesions. No malignancies were discovered at surgical excision or during follow-up of this group of benign lesions. There were no complications related to large-core needle biopsy that required additional treatment. Ultrasonographically guided large-core needle biopsy is a safe and accurate method for evaluating breast lesions that require tissue sampling.

Large-core needle biopsy of nonpalpable breast lesions.

CONTEXT: An increasing number of nonpalpable abnormalities requiring breast biopsy are being identified due to the widespread use of screening mammography. Large-core needle biopsy (LCNB) has become an alternative to surgical excision. OBJECTIVE: To determine whether LCNB is a safe and accurate technique to evaluate nonpalpable abnormalities found on breast imaging studies. DESIGN AND SETTING: Case series at an institutional referral center from August 1, 1991, to December 31, 1997. PATIENTS: A total of 1643 women with 1 or more suspicious breast abnormalities received LCNBs (n = 1836 lesions). INTERVENTION: The LCNB of the breast uses a 14- or 11-gauge needle with stereotactic localization or ultrasound guidance. MAIN OUTCOME MEASURE: Utility and potential limitations of LCNB compared with the criterion standard, surgical excision after wire localization. RESULTS: Of the 1836 breast lesions sampled, 444 (24%) were found to be malignant. A total of 412 (22%) were found to be malignant on the initial LCNB and 202 repeat biopsies yielded 32 additional malignancies. Complications were infrequent: 1 patient experienced a superficial infection and 1 developed a pneumothorax after LCNB. CONCLUSION: Image-guided LCNB is a reliable diagnostic alternative to surgical excision of suspicious nonpalpable breast abnormalities.

Large-needle core biopsy: nonmalignant breast abnormalities evaluated with surgical excision or repeat core biopsy.

PURPOSE: To classify lesions initially considered nonmalignant at large-needle core biopsy that were subsequently surgically excised or sampled at repeat biopsy. MATERIALS AND METHODS: From August 1, 1991, to December 31, 1996, 1,032 breast abnormalities (214 malignant and 818 nonmalignant lesions) were sampled at large-needle core biopsy. Of the nonmalignant lesions, 112 (14%) abnormalities were studied. Twenty-four abnormalities were subsequently excised because of discordant imaging and pathologic findings; 41 may have been missed at biopsy (25 were surgically excised, and 16 were sampled at repeat biopsy); 40 were surgically excised as recommended by the pathologist; and seven were excised for other indications. RESULTS: None of 24 abnormalities excised because of discordant findings was malignant. Among the 41 possibly missed lesions, infiltrating ductal carcinoma was found in one lesion that was removed surgically and in one sampled at repeat biopsy. Among the 40 lesions recommended for excision by the pathologist, 16 malignancies were found (ductal carcinoma in situ, 11; infiltrating ductal carcinoma, three; phyllodes tumor, two). None of the remaining seven lesions was malignant. CONCLUSION: Correlation of the technical quality of the biopsy, imaging features, and pathologic findings resulted in 96 surgical excisions and 16 repeat biopsies of lesions initially considered nonmalignant. Eighteen additional malignancies were identified.

Evaluation of nonpalpable solid breast masses with stereotaxic large-needle core biopsy using a dedicated unit.

OBJECTIVE: In our institution for the past 4 years, stereotaxic core breast biopsy using a 14-gauge needle has been offered as an alternative to surgical excision. The purpose of this paper is to describe our protocol, results, and lessons learned from our experience. MATERIALS AND METHODS: From August 1991 to July 1995, 388 stereotaxic needle core biopsies of clinically occult, noncalcified, mammographically detected solid masses were performed. In this group, 103 patients underwent subsequent surgical excision. Another 169 have had follow-up examinations 1 year or more after their biopsies. RESULTS: Of the 61 patients diagnosed with a malignant process on core biopsy, all had confirmation on subsequent surgical excision. Forty-one of the 42 core biopsies that showed a benign process were subsequently confirmed on surgical excision. One patient with atypical ductal hyperplasia on core biopsy had ductal carcinoma in situ on surgical excision. Patients with 169 benign masses on core biopsy have been followed for at least 1 year by mammography. Of these women, 110 have been followed for at least 2 years, and no malignant lesions have been found. CONCLUSION: Stereotaxic large-needle core biopsy appears to be an accurate alternative to surgical excision for evaluating a solid breast mass. However, the mammographic appearance, technical quality of the biopsy, and pathologic findings in each patient must be correlated to ensure the highest possible accuracy when using this technique.

Image-guided aspiration of solitary occult breast 'cysts'.

During the 30-month period from March 1, 1988, through August 31, 1990, image-guided aspirations of 183 solitary occult breast masses, which were considered possible cysts, were performed. Indications for aspiration included (1) mass on mammography, either invisible on ultrasonography or with features atypical of a cyst, in 111 patients; (2) enlarging solitary mass on mammography with ultrasonic features suggesting a cyst in 45 patients; and (3) mammographic mass with features typical of a cyst in 27 patients, with confirmation requested by the referring physician. Of the group, 151 (83%) lesions were fluid-filled and 32 (17%) were solid. All aspirates had normal cytologic features. Of the 32 aspirates found to be solid, 19 were subsequently removed after wire localization and 13 were unchanged on mammography for a minimum of 6 months after aspiration. This is a simple and safe procedure, confirming the innocuous nature of an occult solitary breast cyst, and obviates the need for surgical biopsy.

Acute rupture of a cystic ovarian teratoma complicating premature labor.

A cystic ovarian teratoma (COT), previously undiagnosed either clinically or by ultrasonography, presented as acute intra-abdominal disease complicating premature labor. This report emphasizes the potentially catastrophic complications of COT and stresses that, despite the availability of ultrasonography, there is still a need for conventional radiography in abdominal catastrophes in pregnant women.