Niraparib first-line maintenance therapy in patients with newly diagnosed advanced ovarian cancer: final overall survival results from the PRIMA/ENGOT-OV26/GOG-3012 trial.

BACKGROUND: The phase III PRIMA/ENGOT-OV26/GOG-3012 trial met its primary endpoint. Niraparib first-line maintenance significantly prolonged progression-free survival (PFS) among patients with newly diagnosed advanced ovarian cancer that responded to first-line platinum-based chemotherapy, regardless of homologous recombination deficiency (HRD) status. Final overall survival (OS) results are reported. PATIENTS AND METHODS: Patients were randomized 2:1 to niraparib or placebo, stratified by response to first-line treatment, receipt of neoadjuvant chemotherapy, and tumor HRD status. After reaching 60% target maturity, OS was evaluated via a stratified log-rank test using randomization stratification factors and summarized using Kaplan-Meier methodology. OS testing was hierarchical [overall population first, then the homologous recombination-deficient (HRd) population]. Other secondary outcomes and long-term safety were assessed; an updated, ad hoc analysis of investigator-assessed PFS was also conducted (cut-off date, 8 April 2024). RESULTS: The median follow-up was 73.9 months. In the overall population, the OS hazard ratio was 1.01 [95% confidence interval (CI) 0.84-1.23; P = 0.8834] for niraparib (n = 487) versus placebo (n = 246). In the HRd (n = 373) and homologous recombination-proficient (n = 249) populations, the OS hazard ratios were 0.95 (95% CI 0.70-1.29) and 0.93 (95% CI 0.69-1.26), respectively. Subsequent poly(ADP-ribose) polymerase inhibitor therapy was received by 11.7% and 15.8% of niraparib patients and 37.8% and 48.4% of placebo patients in the overall and HRd populations, respectively. The 5-year PFS rate numerically favored niraparib in the overall (niraparib, 22%; placebo, 12%) and HRd populations (niraparib, 35%; placebo, 16%). Myelodysplastic syndromes/acute myeloid leukemia incidence was <2.5% (niraparib, 2.3%; placebo, 1.6%). No new safety signals were observed. CONCLUSIONS: In patients with newly diagnosed advanced ovarian cancer at high risk of recurrence, there was no difference in OS between treatment arms. In the HRd population, patients alive at 5 years were two times as likely to be progression free with niraparib treatment than placebo. Long-term safety remained consistent with the established niraparib safety profile.

Health-related quality of life with pembrolizumab monotherapy in patients with previously treated advanced microsatellite instability high/mismatch repair deficient endometrial cancer in the KEYNOTE-158 study.

OBJECTIVE: Pembrolizumab demonstrated a clinically meaningful objective response rate in patients with previously treated, advanced MSI-H/dMMR endometrial cancer in the multicohort phase 2 KEYNOTE-158 study (ClinicalTrials.gov, NCT02628067). We present health-related quality of life (HRQoL) results for these patients. METHODS: This analysis included patients from cohorts D (endometrial cancer with any MSI status) and K (any MSI-H/dMMR solid tumor except colorectal) who had previously treated, advanced MSI-H/dMMR endometrial cancer. Patients received pembrolizumab 200 mg Q3W for 35 cycles. EORTC QLQ-C30 and EQ-5D-3L questionnaires were administered at baseline, at regular intervals during treatment, and 30 days after treatment discontinuation. Pre-specified exploratory analyses included changes from baseline to week 9 in QLQ-C30 global health status (GHS)/QoL and EQ-5D-3L visual analog scale (VAS) score for all patients and by best overall response. RESULTS: 84 of 90 enrolled patients completed ≥1 HRQoL questionnaire and were included in the analysis. QLQ-C30 and EQ-5D-3L compliance rates were 90% and 94%, respectively, at baseline, and 92% and 93% at week 9. Mean (95% CI) QLQ-C30 GHS/QoL scores improved from baseline to week 9 by 6.08 (0.71-11.46) points in the overall population, with greater improvement in patients who achieved complete or partial response (11.67 [5.33-18.00]-point increase). Mean (95% CI) EQ-5D-3L VAS scores improved by 6.00 (2.25-9.75) points in the overall population and 9.11 (5.24-12.98) points in patients with CR/PR. CONCLUSIONS: Pembrolizumab maintained or improved HRQoL in patients with previously treated, advanced MSI-H/dMMR endometrial cancer, further supporting efficacy and safety results from KEYNOTE-158 and pembrolizumab use in this setting.

A phase Ib/II and pharmacokinetic study of EP0057 (formerly CRLX101) in combination with weekly paclitaxel in patients with recurrent or persistent epithelial ovarian, fallopian tube, or primary peritoneal cancer.

BACKGROUND: EP0057 (formerly CRLX101) is an investigational nanoparticle-drug conjugate (NDC) of a cyclodextrin-based polymer backbone plus camptothecin, a topoisomerase-1 inhibitor. Prior studies showed efficacy in recurrent or persistent, epithelial ovarian, fallopian tube or primary peritoneal cancer (EOC). METHODS: This phase Ib/2 trial assessed safety and efficacy of EP0057 Q2W plus weekly paclitaxel in patients with EOC. The recommended phase 2 dose (RP2D) was identified using a 3+3 design. The single-arm phase 2 assessed overall response (ORR) per RECIST 1.1 in patients previously treated with bevacizumab. Secondary objectives included progression free survival (PFS) and duration of response. RESULTS: The RP2D was established as 15 mg/m2 EP0057 Q2W plus 80 mg/m2 paclitaxel administered 3 weeks on/1 week off. Nine patients enrolled on phase 1b, with no DLTs; 21 additional patients enrolled on phase 2. All completed >1 cycle. Median age was 62 (44-76) years, 57% ≥3 prior therapies. For the primary analysis, 6/19 patients with prior bevacizumab had confirmed responses (ORR=31.6% (95% CI: 15.4% to 54.0%)) including one complete response (CR). Median PFS was 5.4 months. Most common grade 3/4 adverse events attributed to treatment were decreased neutrophil count (13, 43%) and anemia (3, 10%). CONCLUSIONS: Although the observed ORR was not statistically better than the historical control rate, EP0057 remains an interesting option for treatment of recurrent EOC. EP0057 exhibits high plasma drug retention, slow clearance, and controlled slow release of CPT from the polymer when administered alone and with paclitaxel. (NCT02389985) 242 words.

Intraperitoneal chemotherapy following neoadjuvant chemotherapy and optimal interval tumor reductive surgery for advanced ovarian cancer.

OBJECTIVES: Intraperitoneal (IP) chemotherapy following neoadjuvant chemotherapy (NACT) and interval tumor reductive surgery (TRS) for advanced ovarian cancer is feasible, however, the impact on disease outcomes remains unclear. We compare outcomes of patients treated with IP chemotherapy versus intravenous (IV) chemotherapy following NACT and interval TRS. METHODS: In this retrospective review, patients with advanced ovarian cancer were included if they received NACT followed by optimal interval TRS between 1/2004 and 4/2017. Patients were excluded if they had an ECOG PS >1, received >6 cycles of NACT or postoperative chemotherapy, and/or received bevacizumab during primary therapy. Primary outcomes were progression free survival (PFS) and overall survival (OS). RESULTS: There were 134 patients included in this study, 37 (28%) received IP and 97 (72%) received IV chemotherapy postoperatively. Patients in the IV group were older (median 66.3 vs 59.7 years, p = 0.0039) though there were no differences in BMI, race, BRCA status, stage, or histology. Median PFS was 3 months longer in the IP group (14.5 versus 11.5 months, p = 0.028) however there was no significant difference in OS. On univariate analysis, increasing number of NACT cycles (HR 1.914, 95% CI 1.024-3.497) and residual disease at completion of TRS (HR 1.541, 95% CI 1.042-2.248) were associated with decreased PFS; IP chemotherapy was associated with increased PFS (HR 0.633, 95% CI 0.414-0.944). These associations remained on multivariate analysis. Toxicity was comparable between the groups. CONCLUSIONS: IP after NACT and optimal interval TRS was associated with in improved PFS compared to IV chemotherapy without significant differences in toxicity.

Outcomes following percutaneous upper gastrointestinal decompressive tube placement for malignant bowel obstruction in ovarian cancer.

OBJECTIVE: The objective of this study was to evaluate peri-operative and survival outcomes of ovarian cancer patients undergoing percutaneous upper gastrointestinal decompression for malignant bowel obstruction (MBO). METHODS: Retrospective chart review was used to identify patients with ovarian, peritoneal, or fallopian tube cancer who underwent palliative decompressive treatment for MBO from 1/2002 to 12/2010. Kaplan-Meier methods were used to estimate the median survival (MS) and multivariate analysis used to determine if any variables were associated with the hazard of death. RESULTS: Fifty-three patients met inclusion criteria. Median length of diagnosis prior to intervention was 21 months. Fifteen (28.3%) patients experienced complications and 9 required revision. Forty-nine (92.5%) experienced relief of symptoms after placement, and 91% tolerated some form of oral intake. Following placement, 19 (36%) patients received additional chemotherapy and 21(41%) patients received total parental nutrition (TPN). Thirty-five patients were discharged home/outpatient facility, 16 to hospice care, and 2 died prior to discharge. MS for all patients was 46 days. Patients who received chemotherapy had a MS of 169 days compared to 33 days (p<0.001). We failed to find an association between survival and TPN or performance status. CONCLUSIONS: Malignant bowel obstruction is a common complication of ovarian cancer. Management is palliative; risks and benefits of any therapy must be considered. Percutaneous decompressive therapy provides relief from associated symptoms, and allows patients to be discharged home. Median survival in this group is limited, and decisions regarding aggressive therapy should be individualized.

Effect of chemotherapy delays and dose reductions on progression free and overall survival in the treatment of epithelial ovarian cancer.

INTRODUCTION: Hematologic, gastrointestinal, and neurologic complications are common side effects of the platinum and taxane-based chemotherapy used in the primary treatment of epithelial ovarian cancer (EOC). These side effects and the impact of the resultant chemotherapy dose modification on disease free interval have not been extensively studied. The goal of this study was to determine the effect of chemotherapy delays and dose reductions on progression free survival (PFS) and overall survival (OS). METHODS: A review of patients with primary epithelial ovarian, peritoneal, and fallopian tube carcinoma treated between 1/2000 and 12/2007 was performed. Inclusion criteria were advanced stage disease and first line chemotherapy with a platinum and taxane regimen. Cox proportional hazard models were used to determine the effect of chemotherapy reductions and delays on PFS and OS. RESULTS: One hundred and fifty seven patients met the inclusion criteria. Patients were divided into four groups: no delays or reductions (48%), delay only (27%), reduction only (8%), and both delay and reduction (18%). The mean number of delays/reductions per patient was 1.1 (range=0-5) and therapy was delayed a mean of 8 days. The most common reasons for delays/reductions were neutropenia (n=51), thrombocytopenia (n=45), and neuropathy (n=18). There were no differences detected in PFS or OS between groups. CONCLUSIONS: There were no differences detected in survival between patients who required dose adjustments and treatment delays and those who did not. The lack of association between survival and chemotherapy alterations suggests that in specific circumstances patients with advanced ovarian cancer should have individualized treatment plans.

Which factors predict bowel complications in patients with recurrent epithelial ovarian cancer being treated with bevacizumab?

BACKGROUND: Increased rates of bowel perforation in patients with recurrent epithelial ovarian cancer (EOC) treated with bevacizumab have been reported, but the risk factors for this association are uncertain. We sought to identify factors associated with bowel perforation and fistula formation in recurrent EOC patients treated with bevacizumab. METHODS: A chart review of all patients treated with bevacizumab for recurrent EOC at a single institution was performed. Pertinent patient characteristics and treatment information were collected. Univariate logistic regression was performed to analyze multiple variables. RESULTS: One hundred twelve patients who were treated with 160 different bevacizumab regimens were identified. The median age was 60 years (range, 29-78 years). Patients had received a median of 4 prior chemotherapy regimens (range, 1-10). The median number of cycles was 4 (range, 0.5-31). Ten patients (9%) were diagnosed with bowel perforations, and another 2 patients (1.8%) were diagnosed with fistulas. The 30-day mortality following perforation was 50%, with 30% of patients dying within 1 week. Patients with rectovaginal nodularity were more likely to develop a bowel perforation or fistula than those who did not have this finding, OR=3.64 (95% CI=1.1 to 12.1, p=0.04). None of the other variables were significantly associated with bowel perforations or fistula formation. CONCLUSIONS: Rectovaginal nodularity is associated with an increased risk of bowel perforation or fistula formation for patients with recurrent EOC treated with bevacizumab. Careful consideration should be given prior to initiating bevacizumab treatment in EOC patients with rectovaginal nodularity since the mortality rate with bevacizumab associated bowel perforations is 50%.

Activation of a multisensory, multifunctional nucleus in the zebrafish midbrain during diverse locomotor behaviors.

Action potentials from the brain control the activity of spinal neural networks to produce, by as yet unknown mechanisms, a variety of motor behaviors. Particularly lacking are details on how identified descending neurons integrate diverse sensory inputs to generate specific locomotor patterns. We have examined the operations of the principal neurons in an intriguing midbrain nucleus, the nucleus of the medial longitudinal fasciculus (nMLF), in the larval zebrafish. The nMLF is the most rostral grouping of neurons that projects from the brain well into the spinal cord of teleost fishes, yet there is little direct physiological data available regarding its function. We report here that a distinct set of large, individually-identifiable neurons in nMLF (the MeL and MeM neurons) are activated by diverse sensory stimuli and contribute to distinct locomotor behaviors. Using in vivo confocal calcium imaging we observed that both photic and mechanical stimuli elicit calcium responses indicative of the firing of action potentials. Calcium responses were observed simultaneously with distinct swimming, turning and struggling movements of the larval trunk. While selectively contralateral responses were at times observed in response to a head-tap stimulus, these nMLF cells showed roughly similar numbers of bilateral responses. Calcium responses were observed at a range of latencies, suggesting involvement with both slow swimming patterns and the burst swimming component of the escape behavior. The MeL cells in particular were strongly activated during light-evoked slow swimming. The activation of MeL cells during the slow and burst forward swim gaits is consistent with their driving and/or coordinating the activity of slow and fast central pattern generators in spinal cord. As such, the MeL cells may help to shape a variety of larval behaviors including the optomotor response, escape swimming and prey capture.

Sustained progression-free survival with weekly paclitaxel and bevacizumab in recurrent ovarian cancer.

OBJECTIVE: To determine efficacy, toxicity, and survival in patients with recurrent epithelial ovarian cancer (EOC) receiving combination of weekly paclitaxel and biweekly bevacizumab (PB). METHODS: We reviewed chemotherapy logs identifying all patients receiving combination PB. Toxicities were graded using CTCAEv3.0 criteria. Response rates (RR) were measured using RECIST criteria or by CA-125 levels per modified Rustin criteria. RR and progression-free survival (PFS) were determined and plotted using Kaplan-Meier survival analysis. RESULTS: Fifty-one patients receiving at least two cycles of chemotherapy were evaluable for survival and 55 patients receiving one cycle of PB were evaluable in toxicity analysis. The mean number of previous regimens was four. The overall median PFS was 7 months and median OS was 12 months. The overall response rate (ORR) was 60% (CR 25% and PR 35%). Median PFS for complete and partial responders were 14 and 5 months respectively. Stable disease was seen in 26% with median PFS of 6 months. Thirteen experienced treatment delays for a variety of factors. The most G3/4 toxicities were fatigue (16%), hematologic (9%) and neurotoxicity (7%). Three patients (5%) experienced bowel perforations. CONCLUSIONS: Combination of paclitaxel and bevacizumab is feasible and demonstrates an acceptable toxicity profile and a high response rate. These observations should be useful in planning future clinical trials with this combination therapy.

Automated identification of neurons in 3D confocal datasets from zebrafish brainstem.

Many kinds of neuroscience data are being acquired regarding the dynamic behaviour and phenotypic diversity of nerve cells. But as the size, complexity and numbers of 3D neuroanatomical datasets grow ever larger, the need for automated detection and analysis of individual neurons takes on greater importance. We describe here a method that detects and identifies neurons within confocal image stacks acquired from the zebrafish brainstem. The first step is to create a template that incorporates the location of all known neurons within a population - in this case the population of reticulospinal cells. Once created, the template is used in conjunction with a sequence of algorithms to determine the 3D location and identity of all fluorescent neurons in each confocal dataset. After an image registration step, neurons are segmented within the confocal image stack and subsequently localized to specific locations within the brainstem template - in many instances identifying neurons as specific, individual reticulospinal cells. This image-processing sequence is fully automated except for the initial selection of three registration points on a maximum projection image. In analysing confocal image stacks that ranged considerably in image quality, we found that this method correctly identified on average approximately 80% of the neurons (if we assume that manual detection by experts constitutes 'ground truth'). Because this identification can be generated approximately 100 times faster than manual identification, it offers a considerable time savings for the investigation of zebrafish reticulospinal neurons. In addition to its cell identification function, this protocol might also be integrated with stereological techniques to enhance quantification of neurons in larger databases. Our focus has been on zebrafish brainstem systems, but the methods described should be applicable to diverse neural architectures including retina, hippocampus and cerebral cortex.

Residents' perspectives on surgical training and the resident-fellow relationship: comparing residency programs with and without gynecological oncology fellowships.

The effect of a gynecological oncology fellow on obstetrics and gynecology resident education and training is uncertain. The objective is to assess the effect of gynecological oncology fellows on the surgical training of residents in obstetrics and gynecology. Fourth year residents in obstetrics and gynecology in the United States were identified and stratified as to the presence or absence of an oncology fellowship program. Demographics, surgical volume, procedures performed, and self-assessment of surgical proficiency were collected. Responses were compared between residency programs with and without fellowships. Responses were received from 40% of programs. Residents at programs without a fellowship more frequently operated with attendings than did residents at programs with fellows, 91% vs 77%, P= 0.016, and more frequently were responsible for complicated cases, 39% vs 22%, P < 0.0001. Over 90% of residents in both groups reported surgical training as positive and valuable; both groups reported a similar perceived lack of proficiency in radical hysterectomy and lymphadenectomy. Attitudes toward the fellows were generally positive; however, competition for cancer cases was reported by over 66% of residents from programs with fellows. While fellows are often thought of as a detracting factor to residency training, they do not appear to affect the perception of the quality of resident surgical training.

Genetics and imaging to assess oocyte and preimplantation embryo health.

Two major criteria are currently used in human assisted reproductive technologies (ART) to evaluate oocyte and preimplantation embryo health: (1) rate of preimplantation embryonic development; and (2) overall morphology. A major gene that regulates the rate of preimplantation development is the preimplantation embryo development (Ped) gene, discovered in our laboratory. In mice, presence of the Ped gene product, Qa-2 protein, results in a fast rate of preimplantation embryonic development, compared with a slow rate of preimplantation embryonic development for embryos that are lacking Qa-2 protein. Moreover, mice that express Qa-2 protein have an overall reproductive advantage that extends beyond the preimplantation period, including higher survival to birth, higher birthweight, and higher survival to weaning. Data are presented that suggest that Qa-2 increases the rate of development of early embryos by acting as a cell-signalling molecule and that phosphatidylinositol-32 kinase is involved in the cell-signalling pathway. The most likely human homologue of Qa-2 has recently been identified as human leukocyte antigen (HLA)-G. Data are presented which show that HLA-G, like Qa-2, is located in lipid rafts, implying that HLA-G also acts as a signalling molecule. In order to better evaluate the second criterion used in ART (i.e. overall morphology), a unique and innovative imaging microscope has been constructed, the Keck 3-D fusion microscope (Keck 3DFM). The Keck 3DFM combines five different microscopic modes into a single platform, allowing multi-modal imaging of the specimen. One of the modes, the quadrature tomographic microscope (QTM), creates digital images of non-stained transparent cells by measuring changes in the index of refraction. Quadrature tomographic microscope images of oocytes and preimplantation mouse embryos are presented for the first time. The digital information from the QTM images should allow the number of cells in a preimplantation embryo to be counted non-invasively. The Keck 3DFM is also being used to assess mitochondrial distribution in mouse oocytes and embryos by using the k-means clustering algorithm. Both the number of cells in preimplantation embryos and mitochondrial distribution are related to oocyte and embryo health. New imaging data obtained from the Keck 3DFM, combined with genetic and biochemical approaches, have the promise of being able to distinguish healthy from unhealthy oocytes and embryos in a non-invasive manner. The goal is to apply the information from our mouse model system to the clinic in order to identify one and only one healthy embryo for transfer back to the mother undergoing an ART procedure. This approach has the potential to increase the success rate of ART and to decrease the high, and undesirable, multiple birth rate presently associated with ART.

Rapid lesioning of large numbers of identified vertebrate neurons: applications in zebrafish.

Establishing a causal role between the activity of specific individual nerve cells and the behaviors they produce (or the neural computations they execute) is made difficult in vertebrate animals because of the large numbers of neurons involved. Traditional techniques for establishing causal roles, such as tract cutting and electrolytic lesions, are limited because they produce damage that affects a variety of different cell types, invariably intermingled, and often of uncertain identity. We propose here an alternative lesioning technique in which large numbers of neurons are lesioned, but the lesioned neurons are specifically identified by fluorescent labeling. We use the locomotor control system of the larval zebrafish to illustrate this approach. In this example, the technique involves injection of fluorescent dextrans into far-rostral spinal cord to label descending nerve fibers. Such injections appear to interrupt the descending nerve fibers, and therefore their accompanying locomotor control signals. This protocol is shown to produce significant behavioral deficits. Because the CNS of the larval zebrafish is transparent, the entire population of lesioned cells can be imaged in vivo and reconstructed using confocal microscopy. This large-scale lesioning technique is important, even in this relatively 'simple' vertebrate animal, because the ablation of smaller numbers of neurons, using more precise laser-ablation techniques, often fails to produce observable behavioral deficits. While this technique is most readily applied in simpler and transparent vertebrate animals, the approach is general in nature and might, in principle, be applied to any vertebrate nerve tract.

Elucidation of new structures in lignins of CAD- and COMT-deficient plants by NMR.

Studying lignin-biosynthetic-pathway mutants and transgenics provides insights into plant responses to perturbations of the lignification system, and enhances our understanding of normal lignification. When enzymes late in the pathway are downregulated, significant changes in the composition and structure of lignin may result. NMR spectroscopy provides powerful diagnostic tools for elucidating structures in the difficult lignin polymer, hinting at the chemical and biochemical changes that have occurred. COMT (caffeic acid O-methyl transferase) downregulation in poplar results in the incorporation of 5-hydroxyconiferyl alcohol into lignins via typical radical coupling reactions, but post-coupling quinone methide internal trapping reactions produce novel benzodioxane units in the lignin. CAD (cinnamyl alcohol dehydrogenase) downregulation results in the incorporation of the hydroxycinnamyl aldehyde monolignol precursors intimately into the polymer. Sinapyl aldehyde cross-couples 8-O-4 with both guaiacyl and syringyl units in the growing polymer, whereas coniferyl aldehyde cross-couples 8-O-4 only with syringyl units, reflecting simple chemical cross-coupling propensities. The incorporation of hydroxycinnamyl aldehyde and 5-hydroxyconiferyl alcohol monomers indicates that these monolignol intermediates are secreted to the cell wall for lignification. The recognition that novel units can incorporate into lignins portends significantly expanded opportunities for engineering the composition and consequent properties of lignin for improved utilization of valuable plant resources.

High-throughput AFLP analysis using infrared dye-labeled primers and an automated DNA sequencer.

Amplified fragment length polymorphism (AFLP) analysis is currently the most powerful and efficient technique for the generation of large numbers of anonymous DNA markers in plant and animal genomes. We have developed a protocol for high-throughput AFLP analysis that allows up to 70,000 polymorphic marker genotype determinations per week on a single automated DNA sequencer. This throughput is based on multiplexed PCR amplification of AFLP fragments using two different infrared dyelabeled primer combinations. The multiplexed AFLPs are resolved on a two-dye, model 4200 LI-COR automated DNA sequencer, and the digital images are scored using semi-automated scoring software specifically designed for complex AFLP banding patterns (AFLP-Quantar). Throughput is enhanced by using high-quality genomic DNA templates obtained by a 96-well DNA isolation procedure.

Evaluation of major genetic loci contributing to inbreeding depression for survival and early growth in a selfed family of Pinus taeda.

The magnitude of fitness effects at genetic loci causing inbreeding depression at various life stages has been an important question in plant evolution. We used genetic mapping in a selfed family of loblolly pine (Pinus taeda L.) to gain insights on inbreeding depression for early growth and viability. Two quantitative trait loci (QTLs) were identified that explain much of the phenotypic variation in height growth through age 3 and may account for more than 13% inbreeding depression in this family. One of these QTLs maps to the location of cad-nl, a lignin biosynthesis mutation. Both QTLs show evidence of overdominance, although evidence for true versus pseudo-overdominance is inconclusive. Evidence of directional dominance for height growth was noted throughout the genome, suggesting that additional loci may contribute to inbreeding depression. A chlorophyll-deficiency mutation, spf did not appear to be associated with growth effects, but had significant effects on survival through age 3. Previously identified embryonic viability loci had little or no overall effect on germination, survival, or growth. Our results challenge, at least in part, the prevailing hypothesis that inbreeding depression for growth is due to alleles of small effect. However, our data support predictions that loci affecting inbreeding depression are largely stage specific.

Locomotor repertoire of the larval zebrafish: swimming, turning and prey capture.

Larval zebrafish (Brachydanio rerio) are a popular model system because of their genetic attributes, transparency and relative simplicity. They have approximately 200 neurons that project from the brainstem into the spinal cord. Many of these neurons can be individually identified and laser-ablated in intact larvae. This should facilitate cellular-level characterization of the descending control of larval behavior patterns. Towards this end, we attempt to describe the range of locomotor behavior patterns exhibited by zebrafish larvae. Using high-speed digital imaging, a variety of swimming and turning behaviors were analyzed in 6- to 9-day-old larval fish. Swimming episodes appeared to fall into two categories, with the point of maximal bending of the larva's body occurring either near the mid-body (burst swims) or closer to the tail (slow swims). Burst swims also involved larger-amplitude bending, faster speeds and greater yaw than slow swims. Turning behaviors clearly fell into two distinct categories: fast, large-angle escape turns characteristic of escape responses, and much slower routine turns lacking the large counterbend that often accompanies escape turns. Prey-capture behaviors were also recorded. They were made up of simpler locomotor components that appeared to be similar to routine turns and slow swims. The different behaviors observed were analyzed with regard to possible underlying neural control systems. Our analysis suggests the existence of discrete sets of controlling neurons and helps to explain the need for the roughly 200 spinal-projecting nerve cells in the brainstem of the larval zebrafish.

Genetic discontinuity revealed by chloroplast microsatellites in eastern North American Abies (Pinaceae).

Development of conservation strategies for Fraser fir (Abies fraseri) in the southern Appalachian Mountains depends in part on recognition of the extent to which Fraser fir is genetically distinct from the closely related balsam (A. balsamea) and intermediate (A. balsamea var. phanerolepis) fir. These sibling species have exhibited intergrading, clinal variation in morphological, chemical, and genetic characteristics in prior research. Chloroplast microsatellite markers were polymerase chain reaction amplified from genomic DNA samples of 78 individuals representing the geographic ranges of Fraser, balsam, and intermediate fir. Gene diversity levels at two loci ranged among taxa from 0.65 to 0.84. Allele frequencies demonstrated significant differentiation among taxa, with R(ST) values of 0.36 and 0.10. Haplotype diversity and D(SH) were highest for balsam fir and lowest for intermediate fir. A haplotype network analysis based on allele size distribution for the two loci revealed two distinct clusters of haplotypes and population-specific haplotypes. Ninety-two percent of the haplotypes in one cluster were from balsam fir and intermediate fir, and 84% of the haplotypes in the other cluster were from Fraser fir and intermediate fir. The genetic differentiation of chloroplast DNA markers provides justification for the recognition of Fraser fir as a distinct Management Unit (MU) for conservation purposes, regardless of its taxonomic classification.

Whole-genome characterization of embryonic stage inbreeding depression in a selfed loblolly pine family.

Inbreeding depression is important in the evolution of plant populations and mating systems. Previous studies have suggested that early-acting inbreeding depression in plants is primarily due to lethal alleles and possibly epistatic interactions. Recent advances in molecular markers now make genetic mapping a powerful tool to study the genetic architecture of inbreeding depression. We describe a genome-wide evaluation of embryonic viability loci in a selfed family of loblolly pine (Pinus taeda L.), using data from AFLP markers from an essentially complete genome map. Locus positions and effects were estimated from segregation ratios using a maximum-likelihood interval mapping procedure. We identified 19 loci showing moderately deleterious to lethal embryonic effects. These loci account for >13 lethal equivalents, greater than the average of 8.5 lethal equivalents reported for loblolly pine. Viability alleles show predominantly recessive action, although potential overdominance occurs at 3 loci. We found no evidence for epistasis in the distribution of pairwise marker correlations or in the regression of fitness on the number of markers linked to deleterious alleles. The predominant role of semilethal alleles in embryonic inbreeding depression has implications for the evolution of isolated populations and for genetic conservation and breeding programs in conifers.