Complementarity of thermoregulatory rhythms in Micropterus salmoides and M. dolomieui

Largemouth (Micropterus salmoide) and smallmouth (M. dolomieui) blackbasses tested in an electronic shuttlebox exhibited behavioral thermoregulatory rhythms which were temporally complementary. With a LD 12 : 12 photoperiod, M. dolomieui exhibited a preferred-temperature peak of 30.1°C during the latter portion of the photophase, when M. salmoides reached a minimum of 27.1°C. M. dolomieui exhibited a minimum of 26.6°C during the latter portion of scotophase, while M. salmoides remained at a significantly higher plateau of about 29°C, with a peak of 29.5°C at the midpoint of scotophase. The phase relations of the thermoregulatory rhythms relative to photoperiod suggest that they are endogenously timed circadian rhythms entrained by photoperiod. The thermotemporal complementarity of these rhythms suggests an aspect of niche segregation between these largely sympatric congeneric species.     

Behavioral thermoregulation by Ammocoete larvae of the sea lamprey (Petromyzon marinus) in an electronic shuttlebox

Ammocoete larvae of the sea lamprey Petromyzon marinus, a member of the primitive vertebrate class Agnatha, were tested for thermoregulatory behavior in an electronic shuttlebox (ichthyotron). The final preferendum derived from pooled data for 24 individually tested ammocoetes was characterized by a mean of 13.6 ± 0.17 (s.e.m.)°C, a mode and median of 140°C, and a range of voluntarily occupied temperatures from 10–19°C over a 3-day period.     

Ultrastructure and isolation of glyoxysomes (microbodies) in zoospores of the fungusentophlyctis sp.

Summary A correlative approach, involving light and electron microscopic, cytochemical, and biochemical techniques, was used to study the structure and function of microbodies in zoospores ofEntophlyctis sp. The same population of microbodies already existing in the zoosporangium appeared to be segregated into zoospore initials during cytoplasmic cleavage. Microbodies laid at the anterior end of zoospores and were part of an organized assemblage of organelles, the microbody-lipid globule complex. In the microbody-lipid globule complex, endoplasmic reticulum occurred on the surface of the lipid globules toward the zoospore's exterior, and the microbody, subtended by mitochondria, was appressed to the opposite surface of the lipid globule. The organization of the microbody-lipid globule complex changed as the zoospore swam and encysted. As lipid globules coalesced, the microbody-lipid globule complex became disorganized. After lipid globule coalescence was completed, the microbody-lipid globule complex regained its order, and several microbodies were clustered adjacent to a single lipid globule. The microbodies persisted even in the encysted zoospore, but they were found on all sides of the lipid globule.Microbodies isolated from zoospores contained catalase as well as malate synthase and isocitrate lyase, two enzymes of the glyoxylate cycle. When zoospores encysted greater activities of these glyoxylate cycle enzymes could be detected. The presence of glyoxylate cycle enzymes and the close association between the microbody and lipid globule suggest that microbodies function as glyoxysomes in zoospores and encysted zoospores. The functional significance of the morphological organization of the microbody-lipid complex is discussed in terms of energy production and the conversion of storage lipid into structural components of the cell.     

Protoplast induction inMicrasterias andCosmarium

Summary Protoplasts of the desmidsMicrasterias angulosa, M. denticulata, M. thomasiana andCosmarium turpinii were obtained by incubating cells in Waris' liquid medium + 0.3 M mannitol + 2% Cellulysin for 1–3 hours. One osmotically fragile protoplast was formed at the isthmus from the joint contents of both semicells. The resultant protoplasts were bright green and remained so for more than 5 days in the osmotically protective medium. The protoplast yield was better than 80%. The empty cell walls were not digested by the Cellulysin or by autolytic enzymes.     

A 25,000 molecular weight protein constituent of human amyloid fibrils related to amyloid protein AA

Amyloid fibrils from a patient with diffuse amyloid disease are dissociated in 6 m guanidine hydrochloride and fractionated by gel chromatography. Two major components are separated on Sepharose 6B. Both proteins are characterized by chromatography, immunodiffusion, discontinuous gel electrophoresis, amino acid tryptic peptide mapping and amino acid sequence analysis. The smaller of the two components is typical of the known protein AA by size (8400 daltons), amino acid composition and a 30-residue N-terminal sequence. The larger of the components (25,000 daltons) undergoes electrophoresis as a single band and appears unaffected by thiol reduction. It differs from protein AA in amino acid content and by its tryptic peptide map, although it contains an N-terminal amino acid sequence identical to protein AA when carried to 20 residues. Treatment of this larger component by mild acid hydrolysis results in the release of the 8400-dalton protein AA. Fractionation after guanidine hydrochloride treatment of this particular amyloid fibril preparation is compared to the fractionation of a typical secondary amyloid preparation that contains only protein AA as the major component. The origin and relationship of the 8,400- and 25,000-dalton protein components is discussed.     

Factors affecting the yield of virus in a cloned cell line of Trichoplusia ni infected with a nuclear polyhedrosis virus

The TN-368 tissue culture line of the cabbage looper, Trichoplusia ni, has been cloned. The doubling times of three clones at 27°C were 27.6 ± 3.4 hr, 21.9 ± 1.7 hr, and 27.4 ± 5.9 hr and that of the uncloned culture was 15.8 ± 1.5 hr. Growth of cells in all cultures was arrested after infection with a nuclear polyhedrosis virus of T. ni. There was little difference in the yield of polyhedra from cultures of uncloned or cloned cells infected at a multiplicity of infection (m.o.i) = 4. Yields of polyhedra were about the same when a m.o.i. was in the range of 0.01–4.0, but the yield tripled in the range m.o.i. = 20–30. At higher multiplicities, up to m.o.i. = 500 the yield of polyhedra progressively fell. It is concluded that the observed variation in numbers of polyhedra borne by individual cells in culture is not due to genetic variability among cells, nor can it be accounted for as a consequence of differing m.o.i. by virus. It is postulated that variation in polyhedra yield among cells in culture may be due to such factors as (1) strain differences in the virus, (2) the stage in the cell cycle at which a particular cell is present when infected.     

Genome-Wide Association Studies in an Isolated Founder Population from the Pacific Island of Kosrae

It has been argued that the limited genetic diversity and reduced allelic heterogeneity observed in isolated founder populations facilitates discovery of loci contributing to both Mendelian and complex disease. A strong founder effect, severe isolation, and substantial inbreeding have dramatically reduced genetic diversity in natives from the island of Kosrae, Federated States of Micronesia, who exhibit a high prevalence of obesity and other metabolic disorders. We hypothesized that genetic drift and possibly natural selection on Kosrae might have increased the frequency of previously rare genetic variants with relatively large effects, making these alleles readily detectable in genome-wide association analysis. However, mapping in large, inbred cohorts introduces analytic challenges, as extensive relatedness between subjects violates the assumptions of independence upon which traditional association test statistics are based. We performed genome-wide association analysis for 15 quantitative traits in 2,906 members of the Kosrae population, using novel approaches to manage the extreme relatedness in the sample. As positive controls, we observe association to known loci for plasma cholesterol, triglycerides, and C-reactive protein and to a compelling candidate loci for thyroid stimulating hormone and fasting plasma glucose. We show that our study is well powered to detect common alleles explaining ≥5% phenotypic variance. However, no such large effects were observed with genome-wide significance, arguing that even in such a severely inbred population, common alleles typically have modest effects. Finally, we show that a majority of common variants discovered in Caucasians have indistinguishable effect sizes on Kosrae, despite the major differences in population genetics and environment.     

Pancreatic lineage analysis using a retroviral vector in embryonic mice demonstrates a common progenitor for endocrine and exocrine cells

The origin of pancreatic endocrine cells is unknown. Some studies have suggested that there is a common pancreatic progenitor which gives rise to both endocrine and exocrine cells, while others have suggested separate endocrine and exocrine lineages. Previous conclusions have been based on indirect data, such as the co-expression of molecular markers. We directly assessed the relationship between endocrine and exocrine cells during development using a lineage tracer. A replication-incompetent retrovirus was used to introduce the reporter gene alkaline phosphatase into single cells in explants of mouse embryonic pancreas. After a week in culture, the subsequent fate of the infected cells could then be determined. The results show that a common pancreatic progenitor cell exists, which gives rise to both endocrine and exocrine cells.     

Transgenic or tumor-induced expression of heparanase upregulates sulfation of heparan sulfate

Heparan sulfate proteoglycans (HSPGs) interact with numerous proteins of importance in animal development and homeostasis. Heparanase, which is expressed in normal tissues and upregulated in angiogenesis, cancer and inflammation, selectively cleaves beta-glucuronidic linkages in HS chains. In a previous study, we transgenically overexpressed heparanase in mice to assess the overall effects of heparanase on HS metabolism. Metabolic labeling confirmed extensive fragmentation of HS in vivo. In the current study we found that in liver showing excessive heparanase overexpression, HSPG turnover is accelerated along with upregulation of HS N- and O-sulfation, thus yielding heparin-like chains without the domain structure typical of HS. Heparanase overexpression in other mouse organs and in human tumors correlated with increased 6-O-sulfation of HS, whereas the domain structure was conserved. The heavily sulfated HS fragments strongly promoted formation of ternary complexes with fibroblast growth factor 1 (FGF1) or FGF2 and FGF receptor 1. Heparanase thus contributes to regulation of HS biosynthesis in a way that may promote growth factor action in tumor angiogenesis and metastasis.     

Using photogrammetry and color scoring to assess sexual dimorphism in wild western gorillas (Gorilla gorilla)

Investigating sexual dimorphism is important for our understanding of its influence on reproductive strategies including male-male competition, mate choice, and sexual conflict. Measuring physical traits in wild animals can be logistically challenging and disruptive for the animals. Therefore body size and ornament variation in wild primates have rarely been quantified. Gorillas are amongst the most sexually dimorphic and dichromatic primates. Adult males (silverbacks) possess a prominent sagittal crest, a pad of fibrous and fatty tissue on top of the head, have red crest coloration, their saddle appears silver, and they possess a silverline along their stomach. Here we measure levels of sexual dimorphism and within-male variation of body length, head size, and sexual dichromatism in a population of wild western gorillas using photogrammetry. Digital photogrammetry is a useful and precise method to measure sexual dimorphism in physical traits yielding sexual dimorphism indices (ISD), similar to those derived from traditional measurements of skeletal remains. Silverbacks were on an average 1.23 times longer in body length than adult females. Sexual dimorphism of head size was highest in measures of crest size (max ISD: 60.4) compared with measures of facial height (max ISD: 24.7). The most sexually dimorphic head size measures also showed the highest within-sex variation. We found no clear sex differences in crest coloration but there was large sexual dichromatism with high within-male variation in saddle coloration and silverline size. Further studies should examine if these sexually dimorphic traits are honest signals of competitive ability and confer an advantage in reproductive success.