Parent Colony Research Articles

Plant Rake and Algal Pouch of the Larvae in the Tropical Ascidian Diplosoma similis: An Adaptation for Vertical Transmission of Photosynthetic Symbionts Prochloron sp

The embryos of Diplosoma similis are brooded within the thick walled tunic of the colony in isolation from the symbiotic algae Prochloron sp., which are in the cloacal cavity of the parent colony. Prior to the spawning, the plant rake, a tassel-like structure, protrudes from the postero-dorsal end of the larval trunk and extends into the cloacal cavity. The algal cells in the cloacal cavity adhere to the plant rake. When the larvae are spawned, the trunk tunic extends posteriorly and forms a pouch entirely covering the plant rake. The algal cells are packed in the pouch (algal pouch) enveloping the basal part of the tail. The cell density of the algae in the pouch is much higher than that in the colony, suggesting that the plant rake functions for gathering and concentrating the symbionts into the algal pouch. In the course of metamorphosis, the algal pouch expands and turns into the cloacal cavity of the young colony. The high density of algal cells in the pouch would ensure that the young colony possesses the symbiotic algae of appropriate cell density in the cloacal cavity, and the colony can sufficiently receive benefits from the symbionts just after the settlement.

Influence of Social Environment on Genetically Based Subfamily Signature in the Honeybee

In honeybees, the cuticular hydrocarbon profiles are partly genetically based and differ between subfamilies, which suggests that they might be used by the workers as labels for subfamily recognition. This ability could potentially form the basis for nepotistic conflicts between subfamilies that would be detrimental to the inclusive fitness of the colony. Here we have compared the subfamily hydrocarbon profiles of 5-day-old workers maintained in isolation with those kept in their parental colony. We demonstrate that the cuticular hydrocarbon profiles tend to be less distant between most subfamilies within the hive compared with those held in isolation. The main consequence of this partial homogenization of the majority of subfamily signatures may result in a reduction of the number of recognizable subfamilies in the colony. Nevertheless, a few subfamilies retain very distinct cuticular hydrocarbon profiles.

Highly resistant Burkholderia pseudomallei small colony variants isolated in vitro and in experimental melioidosis

Burkhloderia pseudomallei is the causative agent of melioidosis, a disease in which treatment failures and relapses are common. This study reports on slow growing B. pseudomallei 'small colony variants' (SCVs), isolated either in vitro after exposure to ceftazidime, ciprofloxacin or gentamicin or from the spleen and liver in a mouse model of melioidosis after treatment with ceftazidime. Interestingly, SCVs isolated by either method or antimicrobial agent showed a significant increase in the minimal inhibitory concentrations of various unrelated classes of antimicrobial agents. B. pseudomallei SCVs did not differ from their parental strains in standard biochemical profiles, nor by pulsed field gel electrophoresis or electron microscopy. Although the SCV phenotype was stable throughout numerous passages on antibiotic-free solid media, revertants with the parental colony morphology and, most importantly, with the parental susceptibility pattern occurred. These revertants led to rapid overgrowth of SCVs in liquid media without added antibiotics. Future studies will have to determine the clinical relevance of B. pseudomallei SCVs especially in treatment failure and relapse of infection.

Long-Term Selection for Resistance to Bacillus thuringiensis Cry1Ac Endotoxin in a Minnesota Population of European Corn Borer (Lepidoptera: Crambidae)

Transgenic corn, expressing the insecticidal δ-endotoxin of Bacillus thuringiensis Berliner, provides high levels of control of some lepidopteran pests, particularly the European corn borer, Ostrinia nubilalis (Hubner). However, resistance to B. thuringiensis has been documented recently in laboratory colonies of agronomically important Lepidoptera, including O. nubilalis. For the past 4 yr, we have selected for Cry1Ac resistance in a population of O. nubilalis from southeastern Minnesota. Increasing resistance to B. thuringiensis was noted after only 8 generations of selection, with a peak at 162-fold resistance, based on comparisons of LC50s to a nonselected parental strain. This resistance was found to decrease at the same rate in the absence of B. thuringiensis selection, with one selected colony becoming nearly as sensitive to the Cry1Ac toxin as the nonselected colony after 9 generations without exposure to B. thuringiensis. The most resistant of the colonies, S-I, was only marginally cross-resistant to Cry1Ab, yet another selected colony, S-IV, did demonstrate a 16-fold cross-resistance. In addition, larvae from the S-IV colony had significantly greater weight gain when feeding on diet incorporated with B. thuringiensis -transgenic corn than did larvae from the nonselected parental colony. These findings emphasize the need for careful deployment of B. thuringiensis corn to preserve this effective pest management technology.

Chemical defence of the soft coral Parerythropodium fulvum fulvum (Forskål) in the Red Sea against generalist reef fish

Abstract Laboratory feeding assays comparing chemical and sclerite deterrence capabilities of Parerythropodium fulvum fulvum revealed that the organic extract deterred feeding by the generalist reef fish Thalassoma klunzingeri (Fowler and Steinitz) and T. lunare (Linnaeus), whereas the sclerites were palatable. The mean number of pellets, containing natural extract concentration as in the living coral, eaten by the test fish was 0.25±0.43, while the mean number of sclerite pellets was 7.0±1.58 out of 10 pellets offered. Extracts of the two colour morphs of the studied species taken from colonies from both shallow and deep reefs deterred feeding by the wrasses even at concentrations as low as 12.5% of the natural concentration present in the coral. Feeding experiments using extracts of embryos of the P. f. fulvum yellow morph revealed that they are chemically protected against predation. A higher level of deterrence was found with extracts of embryos combined with the mucus in which they are embedded. The present study shows that effective defence against predation in the surface-brooded embryos of P. f. fulvum is accomplished by the aggregation of chemically defended embryos, embedded within mucus possessing predator repellent properties; and by the close proximity of the brood to the chemically defended parent colony.

Molecular genetic evidence for the prevalence of outcrossing in the hermaphroditic brooding bryozoan Celleporella hyalina

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 188:73-79 (1999) - doi:10.3354/meps188073 Molecular genetic evidence for the prevalence of outcrossing in the hermaphroditic brooding bryozoan Celleporella hyalina K. Hoare*, R. N. Hughes, A. J. Goldson Brambell Building, School of Biological Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, Wales, UK *Present address: School of Ocean Sciences, University of Wales Bangor, Menai Bridge, Gwynedd LL59 5EY, Wales, UK. E-mail: kh@fferal.freeserve.co.uk ABSTRACT: The occurrence of inbreeding was investigated in Celleporella hyalina, which has been reported as being capable of selfing. In total, 4 tetranucleotide microsatellite markers were scored in populations from sites within the Menai Strait (Wales) and the Yealm Estuary (Plymouth, England). All loci in all populations were in Hardy-Weinberg equilibrium, with insignificant Fis values, which indicates that C. hyalina in these populations generally outbreed. No significant differences were found between populations up to 8 km apart, indicating sufficient gene flow on this scale to form a single breeding population despite geographic separation. The Plymouth population was significantly (p < 0.00001) deviant from the others, indicating possible isolation by distance at the scale of 900 km. C. hyalina cultured in the laboratory were observed to spawn sperm into the surrounding seawater. Sib larvae were found to settle randomly with respect to each other. In isolation C. hyalina failed to produce offspring, though a small proportion brooded abortive embryos. Pairings between individuals of differing genotypes resulted in the production of offspring, all of which, when genotyped with respect to the parent colonies, were found to be the result of outcrossing. KEY WORDS: Inbreeding · Fertilisation · Outcrossing · Sibs · Genetics · Bryozoan · Celleporella Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 188. Publication date: November 03, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Rapid inter-generational changes in morphology and behaviour in colonies of Africanized and European honey bees (Apis mellifera) from tropical Yucatan, Mexico

SUMMARYAn evaluation of honey bee (Apis mellifera) defensive behaviour, worker morphometrics and worker brood cell size was conducted in an apiary in an area undergoing Africanization with the aim of documenting the rate of change of these traits across generations, and their reliability to accurately identify colonies. Ten European and 10 Africanized parental colonies (generation P; groups 1and 2, respectively) were selected in accordance with their morphometrics and subjective evaluation of their behaviour in the field. These colonies were tested for three traits of defensiveness using a standard protocol. Colonies' worker morphometrics and worker cell dimensions were also measured. After the P generation colonies were tested, queens were removed and colonies were allowed to requeen themselves. The virgin queens of the following generation (F1) were allowed to mate freely and, six months later, colonies were again tested. This procedure of mother-daughter queen replacement and testing of colonies was performed two more times (F2 and F3 generations). Wilcoxon- Mann-Whitney tests and Pearson's correlation analysis were used to test for differences between groups in defensive and morphological traits and to determine the relationship between traits in each generation. The results of this study showed that individual colonies dramatically changed their worker morphometrics and defensive behaviour from one generation to the next. However, all colonies, whether originally Africanized or European, came to resemble more the Africanized type across subsequent generations. Correlations between morphometrics and defensive behaviour were not always consistent. Although morphometrics might still be a reliable method for quick identification of colonies it seems that defensive behaviour alone may provide an inadequate trait by which to discriminate among neotropical honey bee types, especially Africanized-European hybrid colonies.

Taxonomic re‐examination of a Chinese strain labeled ‘Eudorinasp.’ (Volvocaceae, Chlorophyta) based on morphological and DNA sequence data

SUMMARYA culture strain, CCFA 646, originating from the People's Republic of China and designated as ‘Eudorinasp.’ in the Culture Collection of Freshwater Algae at the Institute of Hydrobiology, Chinese Academy of Sciences, was re‐examined taxonomically based on light and electron microscopy and molecular phylogenetic analyses. Vegetative colonies of CCFA 646 were sub‐spherical or ovoid and contained 16 or 32 cells of identical size. The cells had a cup‐shaped chloroplast with a single basal pyrenoid. During asexual reproduction, each daughter colony developed within a transparent vesicle inside the parental colony. Under the electron microscope, the vegetative colony exhibited a tripartite colonial boundary of the extracellular matrix. Inside the boundary, each cell was tightly enclosed by a dense fi‐brillar layer of the matrix (cellular envelope). These morphological characteristics suggested that CCFA 646 is assignable toEudorina unicoccaG. M. Smith orYa‐magishiella unicocca(Rayburn et Starr) Nozaki. In addition, 1128 base pairs of the large subunit of ribulose‐1, 5‐bisphosphate carboxylase/oxygenase (rbcL) gene were sequenced from CCFA 646 and NIES‐578 ofY. unicocca. Phylogenetic trees were constructed based on these sequence data as well as on the previously publishedrbcLgene sequences from five strains ofY. unicocca, six strains of fourEudorinaspecies and 28 related species. The sequence data suggested with high bootstrap values that CCFA 646 and all six strains ofYama‐gishiellaform a monophyletic group positioned outside the large monophyletic group comprisingEudorina, Pleo‐dorinaandVolvox(except for sect.Volvox). Therefore, CCFA 646 can be assigned toY. unicocca, which has not previously been reported from P. R. China.

Development of a colony lift immunoassay to facilitate rapid detection and quantification of Escherichia coli O157:H7 from agar plates and filter monitor membranes.

E. coli O157:H7 is a food-borne adulterant that can cause hemorrhagic ulcerative colitis and hemolytic uremic syndrome. Faced with an increasing risk of foods contaminated with E. coli O157:H7, food safety officials are seeking improved methods to detect and isolate E. coli O157:H7 in hazard analysis and critical control point systems in meat- and poultry-processing plants. A colony lift immunoassay was developed to facilitate the positive identification and quantification of E. coli O157:H7 by incorporating a simple colony lift enzyme-linked immunosorbent assay with filter monitors and traditional culture methods. Polyvinylidene difluoride (PVDF) membranes (Millipore, Bedford, Mass.) were prewet with methanol and were used to make replicates of every bacterial colony on agar plates or filter monitor membranes that were then reincubated for 15 to 18 h at 36 +/- 1 degree C, during which the colonies not only remained viable but were reestablished. The membranes were dried, blocked with blocking buffer (Kirkegaard and Perry Laboratories [KPL], Gaithersburg, Md.), and exposed for 7 min to an affinity-purified horseradish peroxidase-labeled goat anti-E. coli O157 antibody (KPL). The membranes were washed, exposed to a 3,3',5,5'-tetramethylbenzidine membrane substrate (TMB; KPL) or aminoethyl carbazole (AEC; Sigma Chemical Co., St. Louis, Mo.), rinsed in deionized water, and air dried. Colonies of E. coli O157:H7 were identified by either a blue (via TMB) or a red (via AEC) color reaction. The colored spots on the PVDF lift membrane were then matched to their respective parent colonies on the agar plates or filter monitor membranes. The colony lift immunoassay was tested with a wide range of genera in the family Enterobacteriaceae as well as different serotypes within the E. coli genus. The colony lift immunoassay provided a simple, rapid, and accurate method for confirming the presence of E. coli O157:H7 colonies isolated on filter monitors or spread plates by traditional culture methods. An advantage of using the colony lift immunoassay is the ability to test every colony serologically on an agar plate or filter monitor membrane simultaneously for the presence of the E. coli O157 antigen. This colony lift immunoassay has recently been successfully incorporated into a rapid-detection, isolation, and quantification system for E. coli O157:H7, developed in our laboratories for retail meat sampling.

Embryogenesis, Planulae Longevity, and Competence in the Octocoral Dendronephthya hemprichi

The development of the azooxanthellate octocoral Dendronephthya hemprichi from spawned gametes to planula larvae has been described, using scanning electron microscopy (SEM). Development of fertilized eggs is holoblastic, occurring until the 32-cell stage either by superficial divisions or by total cleavage. The pseudospiral development from the eight-cell stage leads to round stereoblastulae, followed by the appearance of embryos with bizarre forms. All developmental stages until the mature planulae are negatively buoyant. The planulae have a densely flagellated surface, and swim actively. The duration of development to mature planulae followed a seasonal pattern, ranging between 27-45 h from summer (at 26?C) to winter (at 20?-21?C), and probably reflected temperature effects. Similarly, in summer the first cleavage furrow was observed 2 h after mixing the gametes, whereas in winter this did not occur for at least 4 h. A significant variation was noted in egg diameter and planulae size from different colonies collected at the same time (December 1990). Longevity and maximal competency periods of 100 and 65 days, respectively, were found for the planulae during JulySeptember 1990, suggesting a potential for long distance dispersal in the reef environment. Additional key words: Cnidaria, Octocorallia, development, Red Sea Three modes of larval development have been reported for octocorals to date: a) externally in broadcast spawners, b) by retention of larvae in parent colonies among brooders, or c) in mucous material adhering to the surface of the mother colony (Coma et al. 1995; Benayahu 1997). More than a hundred years ago the mode of cleavage of octocoral eggs had already been illustrated for several species (Kowalevsky & Marion 1883). A century later, embryogenesis and subsequent development into planulae have been documented for a variety of other octocoral species: the gamete spawners Sarcophyton glaucum (Benayahu & Loya 1986), Lobophytum crassum (Uehara et al. 1987), and Plexaura kuna (Lasker & Kim 1996); the brooders Xenia umbellata (Benayahu et al. 1988) and Heteroxeniafuscescens (Benayahu et al. 1989); and the surface brooders Parerythropodium fulvum fulvum (Benayahu & Loya 1983) and Clavularia hamra (Benayahu 1989). Species that spawn gametes provide a ready source for studies on early ontogenetic stages, as opposed to internal brooders for which detection of the developing larvae is complicated by the retention of the embryo a Author for correspondence. E-mail: denlit@ccsg.tau.ac.il in the parent colony (e.g., Babcock & Heyward 1986; Benayahu et al. 1992). Octocorals generally have fairly yolky eggs that undergo holoblastic cleavage (e.g., Benayahu & Loya 1983; Benayahu 1989; Uehara et al. 1987; Lasker & Kim 1996). Their development includes a tendency to superficial cleavage, production of a solid embryo (stereoblastula), and a later transfer of nutritive substances into the archenteron concurrent with germ layer formation (see also Mergner 1971). There are still gaps in the descriptions of various embryonic stages in octocorals, and timing of the developmental events has not been completely mapped. If questions of larval structural or behavioral features, or their longevity and competence, are to be investigated quantitatively, planulae must be raised through to settlement (Babcock & Heyward 1986). In order to accomplish these goals such a study should be preceded by detailed examination of the embryonic cascade, including both structural and temporal aspects. The importance of Octocorallia on many Indo-Pacific reefs, and the lack of information on reproduction of species of the family Nephtheidae (order Alcyonacea), have led us in recent years to examine various aspects of their life history (Benayahu et al. 1992; Benayahu 1997). The azooxanthellate reef-inhabitants of This content downloaded from 157.55.39.180 on Mon, 25 Apr 2016 07:05:15 UTC All use subject to http://about.jstor.org/terms

Aberrant lacrimal gland development in an anophthalmic mutant strain of rat.

Anophthalmia (congenital absence of eyeball) is a rare congenital defect seen in laboratory animals of different species1–6 as well as in humans.7 Several instances of hereditary anophthalmia have been reported,3–6 where both unilateral and bilateral anophthalmic phenotypes have been found. Anophthalmia is also known to result as a teratogenic effect of drugs.7,8 Such teratogenic anophthalmia reported for laboratory rats was found to be bilateral as well as unilateral.8 Our institution has recently isolated a strain of mutant anophthalmic rats that were derived from a parent colony of inbred CFY rats.6

Flow-mediated resource competition in the suspension feeding gorgonian Plexaura homomalla (Esper)

To assess the importance of resource competition in suspension feeders, growth of a common Caribbean gorgonian Plexaura homomalla (Esper) was examined with and without conspecifics. Five small branch sections (i.e., transplants) from a single parent colony were set next to each other in a linear array on a cement flat and maintained in situ in an area characterized by oscillating flow. After one year, we found a systematic decrease in growth rate from the outer to the middle position on these flats, a pattern consistent with expectations of flow-mediated competition for water-borne resources. Competition for water-borne resources is seldom considered among reef taxa, but such competition can play an important role in affecting both intra- and interspecific interactions.

Combined Olfactory Contact with the Parent Colony and Direct Contact with Nonbreeding Animals Does Not Maintain Suppression of Ovulation in Female Naked Mole-Rats (Heterocephalus glaber)

The study investigated the role of odor cues from two naked mole-rat colonies, in conjunction with behavioral cues from nonbreeding colony members, in maintaining suppression of ovulation in subordinate female naked mole-rats isolated from the two parent colonies. Four high ranking nonbreeding female naked mole-rats were removed from their respective parent colonies and singly housed in separate burrow systems. For a 64-day period, the removed females were maintained in daily odor contact with their parent colony by daily rotating soiled bedding material between the parent colony and the burrow systems of removed females. In addition, subsets of nonbreeding animals from the respective parent colony were regularly moved into the burrow systems of removed females for 2-day periods during this 64-day period. Removed females were therefore in continual social contact with subsets of parent colony animals except for the breeding pair. All four removed females exhibited raised levels of urinary progesterone (< 2 ng/mg Cr) indicative of the onset of ovarian function within 3 days of being separated from the parent colony. Removed females exhibited a normal ovulatory cycle with levels of progesterone remaining elevated for 25–35 days (mean concentration of progesterone ± SEM; 16.2 ± 2 ng/mg Cr). Initiation of aggression and sexual behavior by removed females increased significantly when they were isolated from the parent colony. The results demonstrated that odor cues from the complete colony in conjunction with behavioral / tactile / vocal cues from the nonbreeding colony members were not the major cues maintaining reproductive suppression in nonbreeding female naked mole-rats. Instead, our results suggest that female reproductive suppression in naked mole-rats is caused by a dominance-related behavioral mechanism requiring direct contact with the breeding female.

Suggestion of an Environmental Influence on Intercolony Agonism of Formosan Subterranean Termites (Isoptera: Rhinotermitidae)

The role of environmental factors in the intercolonial kin recognition of Coptotermes formosanus Shiraki was investigated using laboratory colonies under similar environmental conditions. Investigation of the parental field colonies found prediction of agonistic interactions based on geographic distance to be unreliable. Agonism did not occur between non-nestmate groups from laboratory colonies. Pairings of field and laboratory groups demonstrated reduced agonism. These results suggested that an environmental cue is part of a multiple component system for intercolony kin recognition in this species.

Longevity, competence and energetic content in planulae of the soft coral Heteroxenia fuscescens

The longevity and competence period of the azooxanthellated planulae of the soft coral Heteroxenia fuscescens, a common shallow-reef inhabitant on the Red Sea reefs, were studied for the first time. The caloric content of the planulae in the course of their life is determined and its possible significance for the longevity and competence periods is considered. H. fuscescens planulae are able to metamorphose immediately upon release and tend to settle adjacent to their parent colonies. The current study presents evidence for absence of a pre-competence period. A maximal longevity of 50 days and a competence of 49 days were recorded, providing an effective dispersal time which encompasses virtually the entire lifespan of the planulae. A monthly variation was found in longevity and competence, possibly temperature related; significantly higher metamorphosis rates occurred during the hotter months of the year, indicating the occurrence of additional temporal variations related to the species reproduction. During late stages of the experiments most of the planulae underwent partial metamorphosis, probably due to a lack of necessary inducers for settlement. It is hypothesized that these polyps may obtain zooxanthellae through their mouth opening, thus acquiring the energy to extend their pelagic life, until they encounter such settlement inducers. Two-day old planulae had a caloric content of 0.58 ± 0.05 cal × planula −1; which decreased gradually with age, to a minimum of 0.35 ± 0.005 cal × planula −1 in 16-day old planulae. H. fuscescens has a wide distribution along the eastern coast of Africa, probably due to the longevity and competence of its planulae.

Immunocytochemical and biochemical characterization of glial phenotypes in normal and immortalized cultures derived from 3-day-old chick embryo encephalon.

We examined properties of glia derived from very early neurogenesis in the chick embryo, as well as their behavior in response to extended cell passages and at various periods in culture. Primary cultures derived from the telencephalic region of 3-day-old chick embryo (stage 19) exhibited intense staining for vimentin (Vim; indicative of immature glial phenotypes) throughout the 17-day culture period, transitioning to Vim-positive/glial fibrillary acidic protein (GFAP)-positive astroblasts after a single cell passage at 13 days in vitro (DIV). With subsequent passage (P; through P6), cell continued to coexpress Vim/GFAP with the occasional appearance of fibronectin (Fib). By P11, Vim staining was faint, whereas GFAP staining gained in intensity, indicating the presence of mature astrocytes. These cultures also featured significant activity of glutamine synthetase (GS), which increased slightly with both cell passage and days in culture, correlating well with immunocytochemical findings. The activity of 2'3'-cyclic nucleotide 3'-phosphohydrolase (CNP) remained low, indicating a low percentage of mature oligodendrocytes. Thus, embryonic day (E)3H glia cultures mature into astrocytes given sufficient time in culture. To obtain a stable population of glia at various stages of astrocytic differentiation, we immortalized and subcloned homogenous colonies of E3H glia precursors at specific stages of development. A cell suspension was electroporetically transfected with the pSV40neo gene for large T antigen (E3H.SV5). After 5 passages, the parent colonies consisted of a heterogeneous population of cells, most of which were vim and GFAP positive. Following subcloning, one line (colony 7) displayed the staining pattern of mature astrocytes. However, with advancing age in culture, staining for both vim and GFAP became increasingly faint. Compared with control (normal) cultures, transfected cells exhibited a significantly lower activity of GS that did not fluctuate with days in culture but decreased with advancing cell passage. Furthermore, CNP activity in E3H.SV5 colony 7 was approximately double that observed in normal cultures at the same cell passage. This observation suggests that the phenotype of transfected glia was less stable than that observed in normal glial cultures.

Life-history variation in three coexisting cheilostome bryozoan species of the genus Stylopoma in Panam�

Life-history variation was studied in three sympatric species of Stylopoma Levinsen [S. spongites (Pallas), S. projecta Canu and Bassler and Stylopoma n. sp. 15] in Panama. Bryozoan colonies were collected from 27 reefs along 300 km of the Caribbean coast of Panama. The distribution and abundance of each species were very patchy, but with broad overlap in occurrence among localities and depths. Nevertheless, species differed considerably in colony size, size at first reproduction and numbers of brooding larvae; implying that interspecific differences in life-history traits may contribute to their coexistence. To examine closely this variation in life-history patterns, we grew, in a common garden experiment, the offspring of the two most common species that were obtained from parent colonies collected from several reefs. There were highly significant differences in growth rates and the timing and extent of sexual reproduction which corresponded well to patterns observed in individuals from the field. Other factors, including size of larvae, extent of secondary zooidal calcification and numbers of avicularia were also correlated with differences in life histories. Despite this additional complexity, however, ecological consequences of trade-offs in life history among modular species such as Stylopoma spp. appear very similar to those among unitary species.

Density‐Dependent Dynamics of Soft Coral Aggregations: The Significance of Clonal Growth and Form

In clonal plants and animals, stolons and runners often promote rapid directional growth and escape from crowded microhabitats. Here we evaluate the effects of density on clonal growth and dispersal by stolons, on colony mortality, and on recruitment in the soft coral Efflatounaria sp. This colonial organism forms dense aggregations on mid—shelf and outer reefs of the Great Barrier Reef, Australia, where it is subjected to frequent physical and biological disturbances. Stolonal growth and asexual recruitment of new colonies (by budding) were enhanced by experimentally reducing local density. Within unmanipulated aggregations of Efflatounaria, per—capita rates of asexual recruitment were higher at low density, but colony survivorship was lower. Furthermore, the effect of density on stolonal growth and dispersal of daughter colonies varied as a function of a colony's history of disturbance. Disturbance was simulated by detaching from the substrate a newly budded colony that was still connected by a stolon to the parent colony. At low density, these pairs of partially detached colonies moved apart, while at high density, stolonally connected colonies moved closer together. Our results suggest that Efflatounaria employs a plastic life—history strategy that promotes recovery from injuries and the formation of dense aggregations. At low density, stolons facilitate rapid directional growth, asexual recruitment, and aggregation. At high density, clonal growth is inhibited, and mortality rates are greatly reduced. Enhanced survival within aggregations provides the adaptive context for interpreting the influence of density and disturbance history on the population dynamics of this clonal organism.

Localization of a tumor suppressor gene in 11p15.5 using the G401 Wilms' tumor assay.

Multiple studies have underscored the importance of loss of tumor suppressor genes in the development of human cancer. To identify these genes, we used somatic cell hybrids in a functional assay for tumor suppression in vivo. A tumor suppressor gene in 11p15.5 was detected by transferring single human chromosomes into the G401 Wilms' tumor cell line. In order to better map this gene, we created a series of radiation-reduced t(X;11) chromosomes and characterized them at 24 loci between H-RAS and beta-globin. Interestingly, three of the chromosomes were indistinguishable as determined by genomic and cytogenetic analyses. Each contains an interstitial deletion with one breakpoint in 11p14.1 and the other breakpoint between the D11S601 and D11S648 loci in 11p15.5. PFGE analysis localized the 11p15.5 breakpoints to a 175 kb MluI fragment that hybridized to D11S601 and D11S648 probes. Genomic fragments from this 175 kb region were hybridized to DNA from mouse hybrid lines containing the delta t(X;11) chromosomes. This analysis detected the identical 11p15.5 breakpoint which disrupts a 7.8 kb EcoRI fragment in all three of the delta t(X;11) chromosomes, suggesting they are subclones of the same parent colony. Upon transfer into G401 cells, one of the chromosomes suppressed tumor formation in nude mice, while the other two chromosomes lacked this ability. Thus, our mapping data indicate that the gene in 11p15.5 which suppresses tumor formation in G401 cells must lie telomeric to the D11S601 locus. Koi et al. (Science 260: 361-364, 1993) have used a similar functional assay to localize a growth suppressor gene for the RD cell line centromeric to the D11S724 locus. The combination of functional studies by our lab and theirs significantly narrows the location of the tumor suppressor gene in 11p15.5 to the approximately 500 kb region between D11S601 and D11S724.

Analysis of mandible of newly developing strain of Japanese white rabbit (Nib:JWNS).

In the present paper, we applied analysis of the mandible to a new strain of Japanese White rabbit being developed (Nib: JWNS), at 5th and 8th generations (F5 and F8), and evaluated the process of establishment, making comparison with the parent colonies (I, K and L), and other established JW colonies (A, E, O and R). The mandibles were measured at 12 sites and the data obtained were calculated by principal component analysis and discriminant analysis. As a result of principal component analysis, the parent colonies were found to be close to one another with intermediate size of the mandible and height of condyloid and angular processes, but in F5 and F8 the mandibles were slightly shorter in height and different from those in the parent colonies. On the other hand, results of discriminant analysis revealed that mandibles were discriminated correctly 100% in colonies A, O and R, and 90% in E and I. Colonies A, O, R, E and I were therefore regarded as established strains. In the developing colonies, the discriminant rate was 70% in F5 and 80% in F8. One mandible from F5 and two from F8 were wrongly classified to the parent colony L, which was the lowest discriminant rate among the colonies examined (61.5%). The results of both statistical analyses suggest that the JWNS are almost established at 8th generation as a new strain.