Karyotype of Pacific red abalone Haliotis rufescens (Archaeogastropoda: Haliotidae) using image analysis.ABSTRACT This report describes a karyotypic analysis in the Pacific red abalone Haliotis rufescens using image analysis. This is the first karyotype reported for this species. Chromosome number and karyotype are the basic information of a genome and important for ploidy ploidy Number of sets of chromosomes in the nucleus of a cell. In normal human body cells, chromosomes exist in pairs, a condition called diploidy. During meiosis the cell produces sex cells (gametes), each containing half the normal number of chromosomes, a condition called manipulation, genomic analysis, and our understanding about chromosomal evolution. In this study we found that the diploid diploid /dip·loid/ (dip´loid) 1. having two sets of chromosomes, as normally found in the somatic cells; in humans, the diploid number is 46. 2. an individual or cell having two full sets of homologous chromosomes. number of chromosomes in the red abalone was 36. Using image analysis by rank-order and digital morphologic filters, it was possible to determine total length of chromosomes and relative arm length in digitally enhanced image, elimination of noise and improving the contrast for the measurements. The karyotype consisted of eight pairs of metacentric chromosomes, eight pairs of submetacentric, one pair submetacentric/metacentric, and one pair of subtelocentric chromosomes. The black abalone, Haliotis cracherodii, also with 36 chromosomes and with a similar geographic distribution, has eight pairs of metacentric metacentric /meta·cen·tric/ (-sen´trik) having the centromere near the middle, so that the arms of the replicating chromosome are approximately equal in length. met·a·cen·tric adj. , eight pairs of submetacentric, and two pairs subtelocentric. This study contributes with new information about the karyology in the family Haliotidae found in California Coast waters and gives some support the Thetys' model about biogeographical bi·o·ge·og·ra·phy n. The study of the geographic distribution of organisms. bi  o·ge·og origin, from the Mediterranean Sea to the East
Pacific Ocean.
KEY WORDS: karyotype, Haliotis refescens, chromosome number, image analysis, red abalone INTRODUCTION Abalones are economically important marine gastropods that reach moderate-to-high prices in the world market (Oakes & Ponte 1996). To date, only eight species of abalone abalone (ăbəlō`nē), popular name in the United States for a univalve gastropod mollusk of the genus Haliotis, members of which are also called ear shells, or sea ears, as their shape resembles the human ear. , Haliotis corrugata, H. cracherodii, H. fulgens, H. kamtschatkana, kamtschatkana, H. k assimilis, H. sorenseni, H. walallensis, and H. rufescens, have been reported in the further East Pacific (Geiger & Poppe Poppe is a surname, and may refer to:
This page or section lists people with the surname Poppe. 2000). The Pacific red abalone, H. rufescens, is found from southern Oregon to northern California in the United States and to the Baja California Peninsula in Mexico (Lindberg 1992). Aquaculture aquaculture, the raising and harvesting of fresh- and saltwater plants and animals. The most economically important form of aquaculture is fish farming, an industry that accounts for an ever increasing share of world fisheries production. production of this species began during the last decade in Mexico, where the whole life cycle is managed under controlled conditions. In addition to the importance on conservation, taxonomic work and karyological analyzes are also useful tools in providing fundamental information for animal breeding programs such as interspecific hybridization interspecific hybridization the results of matings between members of different animal species. (Miyaki et al. 1997) and chromosome-set manipulation (Arai et al. 1986, Fujino et al. 1987, Kudo ku·do n. pl. ku·dos Usage Problem A praising remark; an accolade or compliment: "Children's book author Virginia Hamilton added another kudo to her prize-laden career" et al. 1991, Zhang et al. 1998). A review about the biogeographical origin of the Family Haliotidae reported by Geiger & Groves (1999) using chromosome data in abalone showed that the abalones could be classified in three groups according to their chromosomes number. The first group (2n = 28), inhabits the European-Mediterranean area. The second (2n = 32) inhabits the Indigo-Pacific region, and the third group (2n = 36) represents the abalones of the North Pacific region. Geiger & Groves (1999) suggest that the biogeographical origin of abalone was in the European-Mediterranean area because H. tuberculata (2n = 28) is a relict RELICT. A widow; as A B, relict of C D. species. Most probably this area could have been the starting point of the radiation, extending the distribution of the abalone forward to East from the Indo-Pacific to the North Pacific Ocean. This theory has been called the Tethys' model. In the California Cost, however, karyological data have been performed only for the black abalone H. cracherodii (Minkler, 1977). Thus, more studies are necessary to support the Tethys' model and to know the karyology of abalone species from California Coast. In recent years, great attention has been given to image processing by the use of rank-order statistics. Rank-order and morphologic digital filters can be applied to computer and optical research (Kober et al. 2001a). These digital filters are very efficient in removing additive and impulsive noise, as well as in image enhancing and restoring the microscopical images. The reason for their success in image processing is that they can suppress noise without destroying important image details, such as edges and fines lines. The aim of this work is to describe the karyotype of Pacific red abalone Haliotis rufescens by using rank-order and morphologic filters for suppression of noise and enhancing contrast of the chromosomal images. MATERIALS AND METHODS Gametes Pacific red abalone Haliotis rufescens were obtained from the broodstock kept in the commercial farm "Abulones Cultivados S.A" at Erendira, Baja California, Mexico. The abalones were maintained in a 250-L tank with a recirculating sea water system until the spawning induction. Gametes were obtained through induction spawning according to Morse et al. (1977). Eggs were collected in a 25-[micro]m sieve and resuspended into 2-L container with seawater filtered (0.45 [micro]m) and irradiated with ultraviolet light Ultraviolet light A portion of the light spectrum not visible to the eye. Two bands of the UV spectrum, UVA and UVB, are used to treat psoriasis and other skin diseases. . Fertilization was conducted by adding sperm to the eggs suspension at a final density of 50 sperms per egg. Chromosome Obtaining Twenty to 24 hours after fertilization, swimming trochophore troch·o·phore n. The small, free-swimming, ciliated aquatic larva of various invertebrates, including certain mollusks and annelids. [Greek trokhos, wheel (from trekhein, larvae Larvae, in Roman religion Larvae: see lemures. of pacific red abalone were placed in a 0.005% colchicine colchicine (kŏl`chəsēn'), alkaloid extracted from plants of the genus Colchicum and especially from the corms of the autumn crocus, Colchicum autumnale (see meadow saffron). solution for 3-4 h. After the antimitotic an·ti·mi·tot·ic adj. Preventing or interfering with mitosis: an antimitotic drug. an treatment, the samples were subjected to 45 min in a hypotonic hypotonic /hy·po·ton·ic/ (-ton´ik) 1. denoting decreased tone or tension. 2. denoting a solution having less osmotic pressure than one with which it is compared. solution (50% sea water and distilled water). The larvae were fixed in Carnoy solution (3:1, methanol: acetic acid acetic acid (əsē`tĭk), CH3CO2H, colorless liquid that has a characteristic pungent odor, boils at 118°C;, and is miscible with water in all proportions; it is a weak organic carboxylic acid (see carboxyl group). ) by rinsing the samples three times in the fixative fixative /fix·a·tive/ (fik´sit-iv) an agent used in preserving a histological or pathological specimen so as to maintain the normal structure of its constituent elements. fix·a·tive adj. at intervals of 10 min. Fixed cells were stored at 5[degrees]C overnight in a refrigerator. The sample of cellular suspension was made by cell dissociation in 50% acetic acid and strung agitation with a Pasteur pipette. The cellular suspension was then dropped onto a heated microscope slides (45[degrees]C) and air dried. Chromosome Observation via Computer The chromosomal images were obtained from unstained metaphases. The best 10 images were digitalized with a 24-bit video color frame grabber (model CG-7, Scion sci·on n. 1. A descendant or heir. 2. also ci·on A detached shoot or twig containing buds from a woody plant, used in grafting. Corp.) using a phase-contrast microscopy (Zeizz Axiolab) equipped with a RGB color video camera (model 1040 COHU). To remove impulse noise as well as small undesirable details in chromosomal image, we use rank-order filters with spatially connected neighborhoods (Kober et al. 2001a, 2001b). These filters use spatial and rank information of spatially connected areas of the input image within a moving window to produce the output. The used rank algorithm consists of two steps. Outliers and small details are first detected using spatial relationships between the color image components. Then, the detected pixels are replaced with the output of the vector median filter over a local spatially connected area excluding the outliers, while desired detail and noise-free pixels are left unaltered. The size of a moving window is 7 x 7 elements. The spatially connected neighborhood called as a CEV CEV Crew Exploration Vehicle (NASA) CEV Contemporary English Version (Bible) CEV Confédération Européenne de Volleyball CEV Confederation Européenne de Volleyball neighborhood is defined as a subset of pixels ([v.sub.n,m]) of the moving window, which are spatially connected with the central pixel [v.sub.k,l], and whose values deviate from the value of the central pixel at most by predetermined pre·de·ter·mine v. pre·de·ter·mined, pre·de·ter·min·ing, pre·de·ter·mines v.tr. 1. To determine, decide, or establish in advance: quantities. The rank filter is given by: [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. .] where Thrd is a threshold value of either outlier outlier /out·li·er/ (out´li-er) an observation so distant from the central mass of the data that it noticeably influences results. outlier an extremely high or low value lying beyond the range of the bulk of the data. or undesired detail detection, "-" denotes the set difference operation; S is a small subset of the pixels of the moving window. The pixels associated with outliers after the detection are excluded from the S neighborhood. MED and SIZE denote the median operation and the size of a set, respectively. Identification of homologue homologue /ho·mo·logue/ (hom´ah-log) 1. any homologous organ or part. 2. in chemistry, one of a series of compounds distinguished by addition of a CH2 group in successive members. chromosomes was performed by digital correlation. After identification of homologue chromosomes, determinations of chromosome arm lengths (short and large) were measured with an Image Pro-Plus software version 4.0 (Media Cybernetics cybernetics [Gr.,=steersman], term coined by American mathematician Norbert Wiener to refer to the general analysis of control systems and communication systems in living organisms and machines. ). The measurements were used for determiner relative lengths of chromosomes and centromeric cen·tro·mere n. The most condensed and constricted region of a chromosome, to which the spindle fiber is attached during mitosis. cen index (100 x length of short arm/total chromosome length). The relative lengths of the chromosome arm was plotted the karyo-ideogram according Spotorno (1985). Karyotype was arranged by decreasing size and classified according to Levan et al. (1964). RESULTS All chromosomal images in this study were processed using image analysis. The originals digitals images were obtained with the CCD camera, in this images were preset noise and contrast low, however, after digital image processing Digital image processing is the use of computer algorithms to perform image processing on digital images. Digital image processing has the same advantages over analog image processing as digital signal processing has over analog signal processing — it allows a much wider it is observed a good performance on image edge, enhanced contrast of the chromosomes and allowing mensurations morphologic more exact. Figure 1A, shows the images enhanced of unstained metaphase plate metaphase plate n. An imaginary plane perpendicular to the spindle fibers of a dividing cell, along which chromosomes align during metaphase. by the algorithm. [FIGURE 1 OMITTED] The karyological observations on larvae of Pacific red abalone showed a diploid number equal to 36 chromosomes (Fig. 1A). The distribution of relative chromosome lengths observed was derived to perform the karyotype of Pacific red abalone Haliotis rufenscens (Fig. 1B). The mean values and standard deviations of the relative lengths and total lengths of 18 chromosomes pairs were estimated from arm length measurements in well-spread unstained metaphase plates from the larvae using chromosomal image analysis, the maximum length of the chromosomes was 5.67 [+ or -] 0.56 [micro]m and the minimum was 3.75 [+ or -] 0.071 [micro]m (Table 1). The ratio of the chromosomes arms plotted in the karyo-ideogram indicated that this species possessed eight metacentric pairs (chromosome Nos. 1, 3, 6, 7, 14, 15, 17, and 18), eight submetacentric pair (nos. 2, 4, 5, 8, 9, 10, 11 and 13), one pair (no. 12) was classified as submetacentric/metacentric chromosome and one pair of subtelocentric chromosome (no. 16). Chromosome pairs 14 and 17 were difficult to identify using only such morphologic characteristics as the relative length, because of their mutually overlapping standard deviations (Fig. 2). [FIGURE 2 OMITTED] DISCUSSION To our knowledge, this is the first report of ploidy level and chromosome number in the Pacific red abalone Haliotis rufescens. Karyological studies of abalone species belonging to the North Oriental Pacific are scarce; in fact, only the karyotype of the black abalone H. cracherodii is described with 2n = 36 (Minkler, 1977), since unknown the karyology of Pacific red abalone H. rufescens in the California Coast at present. In contrast, karyological studies in abalones species have been reported in North Occidental Pacific (Arai et al. 1982, Nakamura 1986, Okumura et al. 1999). The morphologic comparison between H. rufescens and H. cracherodii showed that both species comprised 36 chromosomes. However, they are only similar in the metacentric chromosomes number equal to eight pairs. The differences are that red abalone has nine submetacentric pairs (chromosome no. 12, which is submetacentric/ metacentric) and one subtelocentric pair, whereas the back abalone has eight submetacentric pairs and two subtelocentric pairs. This conformation con·for·ma·tion n. One of the spatial arrangements of atoms in a molecule that can come about through free rotation of the atoms about a single chemical bond. of the karyotype in H. cracherodii suggest a deletion process of the short arm in one of submetacentric chromosome pairs, originating an extra subtelocentric pair. It is possible that H. cracherodii was divergent from the one species with more number of submetacentric chromosomes. This suggests that H. cracherodii has a higher genetic difference than H. rufescens. According to Owen et al. (1971) and Leighton (2000), relatively few cases of hybridization hybridization /hy·brid·iza·tion/ (hi?brid-i-za´shun) 1. crossbreeding; the act or process of producing hybrids. 2. molecular hybridization 3. in mollusks have been reported, however, in Haliotis, with the exception of H. cracherodii, each southern Californian species of abalones was found to have hybridized with at least other species. The impossibility the H. cracherodii for hybridize hy·brid·ize intr. & tr.v. hy·brid·ized, hy·brid·iz·ing, hy·brid·iz·es 1. To produce or cause to produce hybrids; crossbreed. 2. with other species of abalones proved genetic distantly related. Phylogenetic phy·lo·ge·net·ic adj. 1. Of or relating to phylogeny or phylogenetics. 2. Relating to or based on evolutionary development or history. relationships studies by Meyer (1967) among California species were analyzed by immunochemical im·mu·no·chem·is·try n. The chemistry of immunologic phenomena, as of antigen-antibody reactions. im comparing of the hemocyanins and showed that phylogenetically phy·lo·ge·net·ic adj. 1. Of or relating to phylogeny or phylogenetics. 2. Relating to or based on evolutionary development or history: a phylogenetic classification of species. close species were distinguished from those more distantly related. Two relatively closely related groups were found; 1) H. rufescens, H. sorenseni, and H. kamtschatkana assimilis, and 2) H. corrugata. H. fulgens, and H. walallensis appeared moderately distinct from these groups, whereas H. cracherodii was decidedly different from the other species. The amino acid amino acid (əmē`nō), any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins. sequences of lysin Lysin A term used to describe substances that will disrupt a cell, with the release of some of its constituents. Unless the damage is minor, this action leads to the death of the cell. proteins of seven California abalone species were deduced from the cDNA sequences (Lee & Vacquier 1992, 1995). These studies are in general agreement with the immunochemical comparison by Meyer (1967), but H. cracherodii was placed closer to H. corrugata, leaving H. fulgens in a more distant relationship to the other California species. Morphometric comparison of chromosomes between the other studied abalone species showed variations of diploid number among 28 to 36 chromosomes (Jarayabhand et al. 1998) (Table 2). The review of diploid chromosome number of the existing karyotypes abalone according to Geiger & Groves (1999), showed that the increment begins in European Mediterranean area with 2n = 28, Indo-Pacific region with 2n = 32 characteristic, except for H. aquatilis with diploid number equal to 34 chromosomes, south Japan area with 2n = 32 and finally Pacific North area with a chromosome number of 36. This study contributed with new information about the karology in the family Haliotidae found in California Cost waters and supports the Thetys' model about biogeographical origin discussed by Geiger & Groves (1999) and Geiger & Poppe (2000).
TABLE 1.
Relative lengths (LR), total lengths (TL), and centromeric index (CI)
of chromosomes of Haliotis rufescens
Chromosome LR (%) TL ([micro]m)
1 6.52 [+ or -] 0.56 5.67 [+ or -] 0.19
2 6.42 [+ or -] 1.03 5.58 [+ or -] 0.07
3 6.20 [+ or -] 0.55 5.39 [+ or -] 0.06
4 6.09 [+ or -] 0.78 5.30 [+ or -] 0.10
5 6.03 [+ or -] 0.91 5.24 [+ or -] 0.01
6 5.97 [+ or -] 0.26 5.20 [+ or -] 0.03
7 5.84 [+ or -] 0.44 5.08 [+ or -] 0.13
8 5.83 [+ or -] 0.68 5.07 [+ or -] 0.07
9 5.74 [+ or -] 1.01 4.99 [+ or -] 0.07
10 5.34 [+ or -] 0.80 4.65 [+ or -] 0.04
11 5.32 [+ or -] 0.70 4.63 [+ or -] 1.09
12 5.26 [+ or -] 0.52 4.58 [+ or -] 0.02
13 5.17 [+ or -] 0.78 4.50 [+ or -] 0.04
14 5.10 [+ or -] 0.17 4.44 [+ or -] 0.07
15 4.96 [+ or -] 0.31 4.32 [+ or -] 0.05
16 4.95 [+ or -] 1.63 4.31 [+ or -] 0.05
17 4.45 [+ or -] 0.27 4.46 [+ or -] 0.06
18 4.31 [+ or -] 0.34 3.75 [+ or -] 0.07
Chromosome CI Type
1 43.95 [+ or -] 0.15 M
2 32.53 [+ or -] 0.18 SM
3 46.91 [+ or -] 0.11 M
4 31.30 [+ or -] 0.13 SM
5 29.91 [+ or -] 0.09 SM
6 44.66 [+ or -] 0.15 M
7 41.68 [+ or -] 0.03 M
8 31.72 [+ or -] 0.29 SM
9 26.38 [+ or -] 0.15 SM
10 28.97 [+ or -] 0.13 SM
11 29.70 [+ or -] 0.13 SM
12 34.67 [+ or -] 0.08 SM/M
13 27.59 [+ or -] 0.17 SM
14 46.34 [+ or -] 0.21 M
15 42.74 [+ or -] 0.20 M
16 16.31 [+ or -] 0.14 ST
17 45.56 [+ or -] 0.15 M
18 44.48 [+ or -] 0.19
MM, metacentric; SM, submetacentric: ST, subtelocentric.
TABLE 2.
Review of diploid chromosome number of abalone.
Haliotis Diploid Number Geographic Occurrence (a)
H. tuberculata 28 European-Mediterranean
H. lamellose 32 European-Mediterranean
H. diversicolor aquatilis 32 Indo-Pacific
H. aquatilis 34 Indo-Pacific
H. diversicolor 32 Indo-Pacific
H. planata 32 Indo-Pacific
H. varia 32 Indo-Pacific
H. asinina 32 Indo-pacific
H. ovina 32 Indo Pacific
H. exigua 32 South Japan
H. discus discus 36 North Pacific
H. discus hannai 36 North Pacific
H. modaka 36 North Pacific
H. cracherodii 36 North Pacific
H. rufenscens 36 North Pacific
Haliotis Reference
H. tuberculata Arai & Wilkins 1986
H. lamellose Colombera & Tagliaferri 1983
H. diversicolor aquatilis Nakamura 1985
H. aquatilis Nakamura 1985
H. diversicolor Arai et al. 1988
H. planata Arai et al. 1988
H. varia Jarayabhand et al. 1998
H. asinina Jarayabhand et al. 1998
H. ovina Jarayabhand et al. 1998
H. exigua Arai et al. 1988
H. discus discus Arai et al. 1982
H. discus hannai Arai et al. 1982, Okumura et al. 1999
H. modaka Nakamura 1986
H. cracherodii Winkler 1977
H. rufenscens This study
(a) Geographical areas according Geiger & Groves 1999.
ACKNOWLEDGMENTS This study was supported by the Mexican National Council of Science and Technology (Project 36075-B). The authors thank to C. Paniagua for manuscript review and for technical assistance. LITERATURE CITED Arai, K. & N. Wilkins. 1986. Chromosomes of Haliotis tuberculata L. Aquaculture 58:305-308. Arai, K., K. Fujino & M. Kudo. 1988. Karyotypes and zymogram zy·mo·gram n. A strip or band of electrophoretic medium showing the pattern of enzymes or isoenzymes after their separation by electrophoresis. differences among three species of the abalones Haliotis planate, H. varia var·i·a n. A miscellany, especially of literary works. [Latin, from neuter pl. of varius, various.] and H. diversicolor diversicolor. Bull. Jpn. Soc. Sci. Fisheries 54: 2055-2064. Arai, K., H. Tsubaki, Y. Ishitani & K. Fujino. 1982. Chromosome of Haliotis discus hannai Inn and H. discus Reeve. Bull. Jpn. Soc. Sci. Fisheries 48:1689-1691. Arai, K., F. Naito & K. Fujino. 1986. Triploidization of the pacific abalone with temperature and pressure treatments. Bull. Jpn. Soc. Sci. Fisheries 52:417-422. Colombera, D. & F. Tagliaferri. 1983. Chromosomes of Haliotis tuberculata and H. lamellose Lam´el`lose` a. 1. Composed of, or having, lamellæ; lamelliform. . Caryologia 36:231-234. Fujino, K., S. Okumura & H. Inayoshi. 1987. Temperature tolerance difference among normal diploid and triploid triploid /trip·loid/ (trip´loid) having triple the haploid number of chromosomes (3n). trip·loid adj. Having three times the haploid number of chromosomes in the cell nucleus. n. Pacific abalones. Nippon Suisan Gakkishi 53:12-21. Geiger, D. & L, Groves. 1999. Review of fossil abalone (Gastropoda: Vestigastropoda: Haliotidae) with comparison to recent species. J. Paleontol. 73:872-885. Geiger, D. & G. Poppe. 2000. A conchological con·chol·o·gy n. The branch of zoology that deals with the study of mollusks and shells. con cho·log iconography. The
Family Haliotidae. New York New York, state, United StatesNew York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of : ConchBooks, pp.327. Jarayabhand, P., R. Yom-La & A. Popongviwat. 1998. Karyotypes of marine mollusks in the family Haliotidae found in Thailand. J. Shellfish Res. 17:761-764, Kober, V., M, Mozerov, J., Alvarez-Borrego. J. Ovseyevich. 2001a. Rank image processing using spatially adaptive neighborhoods, Pattern Recognition Image Analysis 11:542-552. Kober, V., M, Mozerov & J. Alvarez-Borrego. J. 2001b. Nonlinear filters with spatially-connected neighborhoods. Optical Eng, 40:971-983. Kudo, M., K. Arai & K. Fujino. 1991. Triploidization of Halliotis diversicolor diversicolor. Nippon Suisan Gakkishi 57:1263-1267. Lee, Y. & V. Vacquier. 1992. The divergence of species-specific abalone sperm lysins is promoted by positive Darwinian selection. Biol. Bull. 182:97-104. Lee, Y. & V. Vacquier. 1995. Evolution and systematics systematics: see classification. in Haliotidae (Mollusca: Gastrapoda): inferences from DNA sequences of sperm lysin. Marine Biol. 124:267-278. Leighton, D. 2000. The biology and culture of the California abalones. Pittsburgh, PA: Dorrance Publishing Co., Inc. Levan, A., K. Gredga & A. Sandberg. 1964. Nomenclature for centromere centromere Structure in a chromosome that holds together the two chromatids. It is the point of attachment to the structure that pulls the chromatids to opposite ends of the cell during cell division (see mitosis). position on chromosome. Hereditas 52:201-220. Lindberg, D. 1992. Evolution, distribution and systematics of Haliotidae. In: S. Shepherd, M. Tegner & S. Guzman, editors. Abalone of the word. biology, fisheries and cultured. 3-18. Oxford: Fishing News Books. Meyer, R. 1967. Hemocyanins and the systematics of California Haliotis. Ph.D. Dissert dis·ser·tate also dis·sert intr.v. dis·ser·tat·ed also dis·sert·ed, dis·ser·tat·ing also dis·sert·ing, dis·ser·tates also dis·serts To discourse formally. . Stanford Univ. 92 pp. Minkler, J. 1977. Chromosomes of the black abalone (Haliotis cracherodii). Experientia 33:1143. Miyaki, K., O. Tabeta & H. Kayano. 1997. Karyotypes of the two species of abalone Nordotis discus and N. gigantean. Fisheries Sci. 63:179-180. Morse, D., H. Duncan, N. Hooker & A. Morse. 1977. Hydrogen peroxide induces spawning in mollusks, with activation of prostaglandin endoperoxide synthetase synthetase /syn·the·tase/ (-the-tas) a term used in the names of some of the ligases, no longer favored because of its similarity to synthase and its emphasis on reaction products. syn·the·tase n. . Science 196:298-300. Nakamura, H. 1985. The chromosomes of Haliotis diversicolor aquatilis (Archaeogastropoda: Haliotidae). Mol. Rev. 18: 113-114. Nakamura, H. 1986. Chromosomes of Archacogastropoda (Mollusca: Prosobranchia), with some remarks on their citotaxonomy and phylogeny. Pub. Seto Marine Biol. Lab. 31:191-297. Oakes, F. & R. Ponte. 1996. The abalone market: opportunities for cultured abalone. Aquaculture 140:187-195. Okumura, S., S. Kinugawa. A. Fujimaki. W. Kawai. H. Maehata, K. Yoshioka, R. Yoneda & K. Yamamori. 1999. Analysis of karyotype, chromosome banding, and nucleolus organizer region Nucleolus organizer region (NOR) is a chromosomal region around which the nucleolus forms. It is also called the "nucleolar organizer". The region contains several tandem copies of ribosomal RNA genes. See also
Owen, B., J. Mclean & R. Meyer. 1971. Hybridization in the Eastern Pacific abalones (Haliotis). Bull. Los Angeles County Museum Los Angeles County Museum, Los Angeles, Calif. The original museum opened in 1913. Among its important patrons was William Randolph Hearst, whose enormous collection brought the museum major status among the country's art houses. Natural History Sci. 9:1-37. Spotorno, A. 1985. Conceptos y metodos en cariologia descriptiva y comparada. In: Fernandez-Dononso R., editor. El nucleo, los Cromosomas y la Evolucion. UNESCO UNESCO: see United Nations Educational, Scientific, and Cultural Organization. UNESCO in full United Nations Educational, Scientific and Cultural Organization , pp.135-163. Zhang, G., Z. Wang, Y. Chang. Y. Song, Y. Ding, Y. Wang & R. Wang. 1998. Triploid induction in the pacific abalone Haliotis discus hannai Ino by 6-dimethylaminopurine and the performance of triploid juveniles, J. Shellfish Res. 17:783-788. CRISTIAN GALLARDO-ESCARATE, (1,2) JOSUE ALVAREZ-BORREGO, (2), * MIGUEL ANGEL DEL RIO PORTILLA, (1) AND VITALY KOBER (3) (1) Departamento de Acuicultura. Division de Oceanologia, (2) Departamento de Optica, (3) Departamento de Ciencias de la Computacion, Division de Fisica Aplicada, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada. Km 107 Carretera Tijuana--Ensenada, Codigo Postal 22860. Ensenada, B.C. Mexico * Corresponding author. E-mail: josue@cicese.mx |
|
||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion