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  • 1
    Electronic Resource
    Electronic Resource
    Nerol: An alarm substance of the stingless bee,Trigona fulviventris (Hymenoptera: Apidae) (1982)
    Springer
    Journal of chemical ecology 8 (1982), S. 1167-1181 
    Details
    ISSN: 1573-1561
    Keywords: Alarm substance ; nest defense ; nerol ; mandibular gland ; Hymenoptera ; Apidae ; Meliponinae ; stingless bees ; Trigona fulviventris ; Apiomerus pictipes ; Hemiptera ; Reduviidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Bees of the genusTrigona and subgenusTrigona possess volatile materials in their mandibular glands, used as alarm substances and as marking pheromones. Heads of workers ofTrigona fulviventris were analyzed by gas chromatography-mass spectrometry. The two major volatile components were nerol (∼ 50%), and octyl caproate (∼ 20%). Relative to other substances tested at a Costa Rican nest, treatments containing 20 μg of nerol attractedT. fulviventris, depressed numbers of bees leaving the nest by about 50%, and elicited wing vibration and biting. The responses were similar to those obtained with the contents of one worker head. Attraction and biting were also seen in response to captures of colony members by assassin bugs (Apiomerus pictipes) outside a nest entrance; one bee responded in about 15% of the captures. This alarm behavior, although weak, is of interest since it was thought thatT. fulviventris was unusual for its subgenus in its lack of nest defense behaviors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00990750
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  • 2
    Electronic Resource
    Electronic Resource
    Alarm substances of the stingless bee,Trigona silvestriana (1985)
    Springer
    Journal of chemical ecology 11 (1985), S. 409-416 
    Details
    ISSN: 1573-1561
    Keywords: Alarm substances ; nest defense ; 2-heptanol ; 2-nonanol ; mandibular gland ; Hymenoptera ; Apidae ; Meliponinae ; stingless bees ; Trigona silvestriana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 2-Nonanol, 2-heptanol, octyl decanoate, and octyl octanoate were identified from the heads ofTrigona silvestriana workers. When presented at the nest, 2-nonanol, 2-heptanol, and the mixture of the four compounds elicited angular flights, landing, and buzzing of guard bees. Octyl octanoate elicited a weaker response. No response was given to octyl decanoate, to the ether solvent, or to the control volatile, vanillin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00989552
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  • 3
    Electronic Resource
    Electronic Resource
    Germ cell degeneration in normal and microwave-irradiated rats: Potential sperm production rates at different developmental steps in spermatogenesis (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 209 (1984), S. 501-507 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Germ cell degeneration in 14 normal and 14 microwave-irradiated, adult (400-500 gm), Sprague-Dawley rats was compared by evaluating potential sperm production rates at different developmental steps in spermatogenesis. Following 9 days of irradiation at 1.3 GHz (6 hours/day at 6.3 mW/gm using 1-μsec pulsewidth at 600 pulses/second) or sham treatment, rats were killed at 6.5, 13.0, 26.0, or 52.0 days following treatment. Testes were perfused with 2% glutaraldehyde, embedded in Epon, and sectioned at 0.5 μm for morphometric analyses. Plasma LH and FSH concentrations were determined by radioimmunoassay from blood collected on the day of death. Considering nuclear size, percentage of nuclei in the parenchyma, and life span of different cells, potential daily sperm production was determined for type B spermatogonia, preleptotene or pachytene primary spermatocytes, or spermatids with round nuclei. No differences (P 〉 .05) in parameters tested were found among time periods following irradiation. With the possible exception of sperm production per testis (P 〈 .05) based on pachytene spermatocytes, microwave irradiation had no effect on the parameters evaluated. No degeneration was detected in spermatogenesis when potential sperm production rates were determined either from type B spermatogonia to spermatids or from type B spermatogonia to a posttesticular approximation of sperm production rate. Thus, it appears that regulation of sperm production rates must take place during spermatogonial mitoses, since once the number of type B spermatogonia is determined, there is essentially no subsequent alteration in sperm production potential in normal or irradiated adult rats.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092090410
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  • 4
    Electronic Resource
    Electronic Resource
    Flow sorting of X and Y chromosome-bearing mammalian sperm: Activation and pronuclear development of sorted bull, boar, and ram sperm microinjected into hamster oocytes (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 21 (1988), S. 335-343 
    Details
    ISSN: 0148-7280
    Keywords: flow cytometry ; sperm separation ; DNA ; sex ratio ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Flow cytometric techniques were used to measure relative DNA content of X and Y chromosome-bearing bull, boar, and ram sperm populations and to separate the two sex-determining populations. Neat semen was prepared for flow cytometric analysis by washing, light sonication, and staining with 9 μM Hoechst 33342. Computer analysis of the bimodal histograms showed mean X-Y DNA differences of 3.9, 3.7, and 4.2% for bull, boar, and ram, respectively. Flow cytometric reanalysis of sorted bull, boar, and ram sperm showed purities greater than 90%. Bull, boar, and ram sperm nuclei were microinjected into hamster oocytes. Microinjected sperm were either unsorted, sorted, unsorted plus dithio-threitol (DTT) exposure, or sorted plus DTT exposure. Following microinjection, eggs were incubated 3 hr, fixed, and stained. A total of 579 eggs was observed for sperm activation (decondensation or formation of a male pronucleus). A lower percentage of sorted than unsorted (3 vs. 23%) boar sperm was activated (P 〈.05). However, sorted and unsorted DTT-exposed boar sperm or sorted and unsorted bull or ram sperm, regardless of DTT treatment, did not differ significantly. Sorted sperm nuclei of both rams and bulls exhibited higher activation rates than sorted boar sperm (P 〈.05). Treatment of sperm with DTT increased the activation rate (P 〈 .05) for sorted boar sperm but not for bull or ram sperm. These data represent the first separation of bull, boar, and ram X and Y chromosome-bearing sperm populations and the first evidence that sperm of domestic animals sorted on the basis of DNA by flow cytometric procedures have the ability to decondense and to form pronuclei upon injection into a hamster egg.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120210402
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  • 5
    Electronic Resource
    Electronic Resource
    The movement characteristics of rabbit spermatozoa before and after activation (1981)
    New York, NY : Wiley-Blackwell
    Gamete Research 4 (1981), S. 275-282 
    Details
    ISSN: 0148-7280
    Keywords: spermatozoa ; activation ; oviduct ; sperm movements ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Spermatozoa were flushed with mineral oil from the lower isthmus of the rabbit oviduct at four hours postcoitus (pc) and 11 hours pc. Videotapes were made of sperm behavior in the native isthmic fluid and after dilution of the fluid with culture medium. The tapes showed that, initially, spermatozoa in the native isthmic fluid were virtually immotile, but immediately resumed movement on contact with the culture medium. Isthmic sperm motility then evolved over a five- to 10-minute interval into the characteristic biphasic pattern of activated movement. Cine films of isthmic spermatozoa taken with a high-speed camera were analyzed to determine flagellar beat frequency, maximum flagellar curvature, and swimming velocity. Progressiveness ratios and hydrodynamic power outputs were then calculated for individual spermatozoa. Two phases of activated sperm movement, a whiplash phase and a progressive phase, were identified and characterized. The power output of activated spermatozoa increased twentyfold in comparison with the preactivated state. The power output of activated spermatozoa did not differ between the two phases of activated movement.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120040403
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of liquid storage and cryopreservation of boar spermatozoa on acrosomal integrity and the penetration of zona-free hamster ova in vitro (1987)
    New York, NY : Wiley-Blackwell
    Gamete Research 16 (1987), S. 193-204 
    Details
    ISSN: 0148-7280
    Keywords: sperm penetration ; storage ; semen quality ; swine ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effect of liquid storage and cryopreservation of boar spermatozoa on sperm motility, acrosomal integrity, and the penetration of zona-free hamster (ZFH) ova was examined. The sperm penetration assay (SPA) provides valuable information on specific events of fertilization and is a potentially useful indicator of sperm fertility. Ejaculated semen from 4 boars was subjected to 3 treatments: fresh (FRE, no storage), liquid-stored (LIS, stored at 18°C for 3 days), and frozen (FRO, frozen by pellet method and stored at -196°C for 3 days). A highly motile sperm population was isolated by the swim-up procedure (1 hr). FRE and LIS were incubated an additional 3 hr at 39°C in a Tris-buffered medium to elicit capacitation and the acrosome reaction. Sperm motility and acrosomal integrity were assessed before and after incubation. For the SPA, sperm and eggs were incubated at 39°C for 3 hr in Hams F-10 medium. Each egg was assessed for sperm penetration, sperm binding, and stage of development. Percentages of sperm motility and sperm with a normal apical ridge (NAR) prior to incubation were 78 and 78 (FRE), 75 and 69 (LIS), and 28 and 50 (FRO). After incubation, percentages of motility, NAR, and acrosome-reacted sperm were 34, 10, and 73 (FRE); 43, 24, and 51 (LIS); and 18, 13, and 59 (FRO). A somewhat higher (P 〈 .05) percentage of ZFH ova was penetrated by FRE (45.8) than by LIS (42.0). Penetration of ZFH ova by FRO was markedly (P 〈 .05) reduced (30.2). Sperm penetration was not significantly correlated with motility or acrosomal integrity before or after incubation, regardless of treatment. These data suggest that the SPA can be used in conjunction with conventional measures of semen analysis in assessing the potential fertilizing capacity of boar sperm and that liquid storage is superior to frozen storage with respect to preserving sperm fertility.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120160302
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  • 7
    Electronic Resource
    Electronic Resource
    Novel gene exon homologous to pancreatic phospholipase A2: Sequence and chromosomal mapping of both human genes (1989)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 39 (1989), S. 327-337 
    Details
    ISSN: 0730-2312
    Keywords: phospholipase A2 ; human genes ; pancreatic ; human chromosome mapping ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We described previously the cloning and DNA sequence of the human gene encoding pancreatic phospholipase A2 [DNA 5, 519]. When pancreatic phospholipase A2 (PLA2) cDNA was used to screen a human genomic library, two classes of clones were obtained. One class encoded the pancreatic enzyme, and a second class encoded one exon of an apparently related PLA2. No additional PLA2 gene exons displayed sufficient homology to be detected by the probe. A homologous sequence in both rat and porcine genomic DNA was detected by DNA blot hybridization, and the corresponding gene fragments were cloned and sequenced. Within the deduced amino acid sequences, the presence of known functional residues along with the high degree of interspecies conservation suggests the genes encode a functional PLA2 enzyme form. The encoded sequence lacks Cys11, as do the “type II” viperid venom and other nonpancreatic mammalian PLA2 enzymes. The sequence is distinct from porcine intestinal PLA2 and appears not to be a direct homolog of the recently published rabbit ascites and rat platelet enzymes. Hybridization of DNA probes containing sequences from these genes to genomic DNA blots of mouse/human somatic cell hybrids permitted chromosomal assignment for both. The pancreatic gene mapped to human chromosome 12, and the homologous gene mapped to chromosome 1.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240390312
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  • 8
    Electronic Resource
    Electronic Resource
    Proliferative variability of endothelial clones derived from adult bovine aorta: Influence of fibroblast growth factor and smooth muscle cell extracellular matrix (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 114 (1983), S. 7-15 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Four endothelial cell clones derived from adult bovine aorta were examined with respect to their proliferative characteristics In vitro. Three of these clones, derived in the absence of fibroblast growth factor (FGF), displayed variable basal proliferative rates. One of these non-FGF derived clones grew at a maximal rate which could not be further enhanced with FGF. The other two clones grew at a suboptimal rate which was stimulated by low doses of FGF (10-50 ng/ml) and inhibited by higher doses (100-250 ng/ml). The fourth clone, derived in the presence of FGF, was stimulated by FGF in a dose-dependent manner (10-250 ng/ml) and was not growth inhibited at high FGF concentrations (250-1,000 ng/ml). Growth of all four clones on extracellular matrix (ECM) derived from bovine aortic smooth muscle (BASM) cells was optimal in the absence of FGF. ECM-coated dishes also significantly increased the sensitivity of all clones by at least fivefold to mitogenic stimulation by serum. The proliferative lifespans of the clones ranged between 60 and 120 generations with the most actively proliferating clones attaining the greatest lifespan. Continuous subculture of two of the endothelial clones in the presence of FGF or on ECM-coated dishes did not induce a dependence of the cells on either factor for subsequent growth in its absence. The results indicate that aortic endothelial cells display considerable clonal variability in ther basal proliferative rate and in their response to FGF. This clonal variability is not observed when the cells are maintained on ECM-coated dishes derived from vascular smooth muscle cells.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041140103
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  • 9
    Electronic Resource
    Electronic Resource
    Inhibition of low density lipoprotein uptake in confluent endothelial cell monolayers correlates with a restricted surface receptor redistribution (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 100 (1979), S. 481-495 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Binding of either low density lipoprotein (LDL) or Concanavalin A (ConA) to actively growing vascular endothelial cells is associated with a redistribution of the appropriate cell surface receptor sites which form patches and caps. This receptor lateral mobility is greatly restricted when endothelial cells reach confluence and adopt the configuration of a cell monolayer composed of closely apposed and non-overlapping cells. In this case, although the cells still exhibit specific LDL binding to the appropriate cell surface receptor sites, neither the binding of LDL nor of ConA induces a receptor redistribution. The lack of LDL receptor redistribution correlates with a marked decrease in the rate of LDL internalization. In contrast, no such a density-dependent changes are observed in cell types which grow on top of each other and form multiple cell layers at confluence. Thus, neither LDL nor ConA induced cap formation in either sparse or confluent smooth muscle cell cultures and the same rate of LDL internalization is observed at both cell densities. Similarly, adsorptive endocytosis of cationized LDL (which enters the cell independently of the LDL receptor sites) was not correlated with a detectable receptor redistribution, nor was it significantly affected by changes in cell density and spatial organization.The formation of a confluent cell monolayer resting on an underlying basement membrane might therefore provide, via a change in membrane dynamics, a mechanism whereby the endothelium of large blood vessels can function as a protective barrier against the high circulating levels of LDL in plasma.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041000311
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  • 10
    Electronic Resource
    Electronic Resource
    Delayed processing/export of messenger RNA under conditions of reduced protein synthesis (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 115-121 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rates of processing and export of a variety of nuclear RNA species into the cytoplasmic compartment were studied by determining the rates of incorportion of tritiated uridine into nuclear and cytoplasmic RNA species. In exponentially growing cells, the rates of nuclear processing/export varied by more than a factor of ten for the six different mRNA species that were examined. Differences in the rates did not appear to be correlated with either the number or the sizes of introns in the genes for the RNA species. When cells were maintained under conditions of reduced protein synthesis (starvation for isoleucine and glutamine or exposure to cycloheximide), the processing rates for each species decreased by a factor of about 3. The decrease was not caused by the inability of hnRNA to associate with proteins, since the nuclear RNP distribution appeared normal in amino acidstarved cells.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041350116
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