CONTEMPORARY EVOLUTION OF SEA URCHIN GAMETE-RECOGNITION PROTEINS: EXPERIMENTAL EVIDENCE OF DENSITY-DEPENDENT GAMETE PERFORMANCE PREDICTS SHIFTS IN ALLELE FREQUENCIES OVER TIME

In 1959, Afzelius observed the presence of two rows of arms projecting from each outer doublet microtubule of the so-called 9 + 2 pattern of cilia and flagella, and suggested a possibility that the outer doublet microtubules slide with respect to each other with the aid of these arms during ciliary and flagellar movement. The identification of the arms as an ATPase, dynein, by Gibbons (1963)strengthened this hypothesis, since the ATPase-bearing heads of myosin molecules projecting from the thick filaments pull the thin filaments by cross-bridge formation during muscle contraction. The first experimental evidence for the sliding mechanism in cilia and flagella was obtained by examining the tip patterns of molluscan gill cilia by Satir (1965) who observed constant length of the microtubules during ciliary bending. Further evidence for the sliding-tubule mechanism was given by Summers and Gibbons (1971), using trypsin-treated axonemal fragments of sea urchin spermatozoa. Upon the addition of ATP, the outer doublets telescoped out from these fragments and the total length reached up to seven or more times that of the original fragment. Thus, the arms on a certain doublet microtubule can walk along the adjacent doublet when the doublet microtubules are disconnected by digestion of the interdoublet links which connect them with each other, or the radial spokes which connect them with the central pair-central sheath complex as illustrated in Fig. 1. On the basis of these pioneer works, the sliding-tubule mechanism has been established as one of the basic mechanisms for ciliary and flagellar movement.

Download Full-text

What makes a species common? No evidence of density-dependent recruitment or mortality of the sea urchin Diadema antillarum after the 1983–1984 mass mortality

Oecologia ◽

10.1007/s00442-013-2871-9 ◽

2014 ◽

Vol 175 (1) ◽

pp. 117-128 ◽

Cited By ~ 24

Author(s):

Don R. Levitan ◽

Peter J. Edmunds ◽

Keeha E. Levitan

Keyword(s):

Sea Urchin ◽

Mass Mortality ◽

Diadema Antillarum ◽

Density Dependent

Download Full-text

DENSIDAD POBLACIONAL DE CUATRO ESPECIES DE ERIZO (ECHINODERMATA: ECHINOIDEA) EN EL ARRECIFE DE LA ENTREGA, OAXACA

CICIMAR Oceánides ◽

10.37543/oceanides.v20i1-2.22 ◽

2005 ◽

Vol 20 (1-2) ◽

pp. 65

Author(s):

P. Zamorano ◽

G. E. Leyte-Morales

Keyword(s):

Population Density ◽

Sea Urchin ◽

Sea Urchins ◽

Depth Range ◽

Deep Zone ◽

Total Abundance ◽

Subsequent Increase ◽

Shallow Zone ◽

Over Time ◽

Shallow Part

De octubre de 2002 a agosto de 2003 se realizaron muestreos bimestrales de la abundancia de erizos en el arrecife de La Entrega. El arrecife fue dividido en dos profundidades (somero 0-6 m y profundo 6-12 m). En cada profundidad se realizaron seis transectos de 50 m de largo por 1 m de ancho. La mayor densidad anual correspondió a Diadema mexicanum (5.96±0.85 ind/m2), seguido de Eucidaris thouarsii (0.46±0.14 ind/m2); Echinometra vanbrunti y Toxopneustes roseus presentaron densidades bajas (0.03±0.01 ind/m2 y 0.02±0.01 ind/m2, respectivamente). Las cuatro poblaciones de erizos presentaron diferencias entre profundidades observándose mayor densidad en lo profundo; si consideramos la abundancia total de erizos en el arrecife, no se registraron diferencias temporales. Empero, al analizar por separado las profundidades, sólo E. thouarsii no presentó diferencias temporales en ambas profundidades. En diciembre, las densidades de D. mexicanum y E. thouarsii disminuyeron en lo profundo y aumentaron en lo somero, posiblemente porque sucedió una mortalidad coralina en lo somero del arrecife y el incremento de las algas motivó a estas especies a desplazarse a la parte dañada. Actualmente el arrecife de La Entrega se encuentra en avanzado estado de erosión lo que puede favorecer que la abundancia de erizos se incremente al igual que su actividad bioerosionadora. Population density of four species of sea urchin (Echinodermata: Echinoidea) at La Entrega Reef, Oaxaca Bimonthly samples of sea urchins fauna inhabiting the La Entrega Reef, Oaxaca, Mexico, were obtained from October 2002 to August 2003. The reef area was divided in two sampling zones, corresponding to shallow (0-6 m) and deep (6-12 m) water. Six transects of 50 m length by 1 m wide were sampled in each zone. Greatest annual density corresponded to Diadema mexicanum (5.96 ± 0.85 ind/m2),followed by Eucidaris thouarsii (0.46 ± 0.14 ind/m2); Echinometra vanbrunti and Toxopneustes roseus presented low densities (0.03 ± 0.01 indv/m2 and 0.02 ± 0.01 ind/m2, respectively). Density of the four populations varied considerably and higher densities were observed in the deep zone. Total abundance of sea urchins (shallow and deep samples) did not vary significantly over time. Abundance per depth range, however, was different over time for all species except for E. thouarsii. In December densities of D. mexicanum and E. thouarsii decreased in the deep zone and increased in the shallow zone, due to massive mortality of coral in the shallow part of the reef and to subsequent increase of algal coverage attracting these species to the shallowest part of the reef. The La Entrega reef is presently in an advanced state of erosion that could favor an increase of sea urchins abundance and of their bioerosion activity.

Download Full-text

Do Sperm Really Compete and Do Eggs Ever Have a Choice? Adult Distribution and Gamete Mixing Influence Sexual Selection, Sexual Conflict, and the Evolution of Gamete Recognition Proteins in the Sea

The American Naturalist ◽

10.1086/694780 ◽

2018 ◽

Vol 191 (1) ◽

pp. 88-105 ◽

Cited By ~ 15

Author(s):

Don R. Levitan

Keyword(s):

Sexual Selection ◽

Sexual Conflict ◽

Gamete Recognition ◽

Gamete Recognition Proteins

Download Full-text

Effects of Egg Size on Postlarval Performance: Experimental Evidence from a Sea Urchin

Evolution ◽

10.2307/2410967 ◽

1997 ◽

Vol 51 (1) ◽

pp. 141 ◽

Cited By ~ 43

Author(s):

Richard B. Emlet ◽

Ove Hoegh-Guldberg

Keyword(s):

Experimental Evidence ◽

Sea Urchin ◽

Egg Size

Download Full-text

Selection on Gamete Recognition Proteins Depends on Sex, Density, and Genotype Frequency

Science ◽

10.1126/science.1122183 ◽

2006 ◽

Vol 312 (5771) ◽

pp. 267-269 ◽

Cited By ~ 115

Author(s):

D. R. Levitan

Keyword(s):

Genotype Frequency ◽

Gamete Recognition ◽

Gamete Recognition Proteins

Download Full-text

BRCA1/2 reversion mutations revealed in breast and gynecologic cancers sequenced during routine clinical care using tissue or liquid biopsy.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.5551 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. 5551-5551 ◽

Cited By ~ 1

Author(s):

Paul Mayor ◽

Laurie M. Gay ◽

Erica Gornstein ◽

Samantha Morley ◽

Garrett Michael Frampton ◽

...

Keyword(s):

Missense Mutation ◽

Liquid Biopsy ◽

Clinical Care ◽

Metastatic Breast ◽

Allele Frequencies ◽

Genomic Alteration ◽

Liquid Biopsies ◽

Peritoneal Cancer ◽

Routine Clinical Care ◽

Over Time

5551 Background: Tumors with genomic alteration (GA) of BRCA1 or BRCA2 ( BRCA) may be more sensitive to platinum (Pt) therapies and PARP inhibitors (PARPi). However, secondary reversion mutations (revGA) can arise that may restore BRCA function and underlie reduced sensitivity to Pt compounds or PARPi. Methods: DNA extracted from FFPE tumor tissue or blood samples obtained during routine clinical care for patients with predominantly relapsed, refractory or metastatic breast cancer (10967) or ovarian/peritoneal cancer (8352) was analyzed by hybrid-capture, next-generation sequencing for all classes of GA: base substitutions, indels, rearrangements, and copy number changes. RevGA were any GA that could restore the reading frame if in cis with a nonsense or frameshift (fs) GA. Results: 1900/19329 (9.8% ± 0.4%) tumors had ≥1 deleterious BRCA GA. 38 samples harbored potential revGA in BRCA1 (16) or BRCA2 (22): breast carcinoma (Ca) (21), ovarian or peritoneal serous Ca (10), ovarian or peritoneal adenocarcinoma (3), and ovarian epithelial Ca NOS (4). 35/38 sequenced samples were metastases. All potential revGA were somatic and fell into 3 classes: overlapping indel (21), compensatory fs (6), and missense mutation (11). One case harbored both an overlapping indel and a missense mutation with potential to revert a nonsense alteration. For 6 patients, testing of multiple tissue samples reveals the acquisition of revGA over time. RevGA are generally observed at allele frequencies lower than the deleterious GA they may revert. Clinical histories for patients with reversion mutations will be presented. Conclusions: Genomic profiling of breast and gynecological carcinomas, using either tissue or liquid biopsies, reveals potential revGA that may restore some level of BRCA function. RevGA, although rare, can be acquired during the course of treatment. We identified potentially compensatory missense, fs and indel mutations with CGP. Comparison of allele frequencies suggests that revGA often arise as subclones. The acquisition of a revGA over time can be observed through testing of multiple samples, either tissue or liquid biopsy.

Download Full-text