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Topic: Karyogamy

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	Phycologia: Karyogamy follows plasmogamy in the life cycle of Derbesia tenuissima (Chlorophyta) (Site not responding. Last check: 2007-10-09)
		The finding of zygotic karyogamy suggests that the sporophyte of this species develops from a diploid homokaryotic zygote, and this disputes interpretations of the life history of Derbesia based on microspectrophotometric studies.
		The life cycle of all three species was reported to be haplo- heterokaryotic because the level of nuclear DNA contents found in both sporophytes and gametophytes was the same as that in haploid gametes and because nuclei with diploid DNA levels were found only in young sporangia.
		In mating experiments with D. tenuissima gametes (female gametes were prestained with acridine orange), two unfused nuclei in a 15-min-old zygote and four nuclei in a 4-h-old zygote were observed, suggesting that in the zygote of Der!oesia, mitosis of both male and female gametic nuclei might occur without the nuclei being fused.
	www.findarticles.com /p/articles/mi_qa3850/is_199809/ai_n8823327 (1354 words)

	Sexual reproduction (from fungus) -- Britannica Concise Encyclopedia - The online encyclopedia you can trust!
		The nucleolus is usually also retained and divided between the daughter cells, although it may be expelled from the nucleus, or it may be dispersed within the nucleus but detectable.
		Karyogamy results in the fusion of these haploid nuclei and the formation of a diploid nucleus (i.e., a nucleus containing two sets of chromosomes, one from each parent).
		Once karyogamy has occurred, meiosis (cell division that reduces the chromosome number to one set per cell) generally follows immediately and restores the haploid phase.
	www.britannica.com /ebc/article-57957 (1263 words)

	Medmicro Chapter 73
		Sexual reproduction occurs by the fusion of two haploid nuclei (karyogamy), followed by meiotic division of the diploid nucleus.
		The union of two hyphal protoplasts (plasmogamy) may be followed immediately by karyogamy, or it may be separated in time.
		Karyogamy may be delayed until considerably later in the life history of the fungus.
	gsbs.utmb.edu /microbook/ch073.htm (2093 words)

	KAR5 Encodes a Novel Pheromone-inducible Protein Required for Homotypic Nuclear Fusion -- Beh et al. 139 (5): 1063 -- ...
		Nuclear envelope fusion during karyogamy is a prime example of homotypic membrane fusion.
		the karyogamy genes KAR4, KAR5, KAR7, KAR8, and KAR9.
		KAR2, a karyogamy gene, is the yeast homologue of the mammalian BiP/GRP78 gene.
	www.jcb.org /cgi/content/full/139/5/1063 (8656 words)

	Genetic Interactions between KAR7/SEC71, KAR8/JEM1, KAR5, and KAR2 during Nuclear Fusion in Saccharomyces cerevisiae -- ...
		Nuclear fusion (karyogamy) is the last step in the mating pathway that culminates in the formation of a diploid cell.
		on the karyogamy phenotype of sec63-201 × sec63-201 zygotes (48%
		Gammie, A., Stewart, B.G., Scott, C.F., and Rose, M.D. The two forms of karyogamy transcription factor Kar4p are regulated by differential initiation of transcription, translation, and protein turnover.
	www.molbiolcell.org /cgi/content/full/10/3/609 (7286 words)

	Sequential involvement of Cdk1, mTOR and p53 in apoptosis induced by the HIV-1 envelope
		Karyogamy induced by the Env−CD4/CXCR4 interaction occurred before apoptotic nuclear chromatin condensation (detected with Hoechst 33342, Figure 1A) and DNA degradation (detected by TUNEL staining, Figure 1B).
		Unexpectedly, however, rapamycin reduced karyogamy in HeLa Env/HeLa CD4 heterokarya (Figure 4C), an observation that is reminiscent of that obtained in Saccharomyces cerevisiae, in which rapamycin can inhibit karyogamy (Choi et al., 2000).
		Altogether, these changes resemble 'mitotic catastrophe' (Pines, 1999), an apoptosis-like process that begins in prophase, after dissolution of the nuclear membrane, and is associated with the entry of Cdk1 and cyclin B into the nucleus, which can be found in a minority of stage I cells (Figure 2G).
	www.nature.com /cgi-taf/dynapage.taf?file=/emboj/journal/v21/n15/full/7594613a.html (6438 words)

	Learn more about Fungus in the online encyclopedia. (Site not responding. Last check: 2007-10-09)
		The result is that nuclei move from one mycelium into the other, forming a heterokaryon (meaning different nuclei).
		Actual fusion to form diploid nuclei is called karyogamy, and may not occur until sporangia are formed.
		In the Zygomycota, the heterokaryon produces multiple fruiting bodies, in the form of minuscule stalks with sporangia at the end.
	www.onlineencyclopedia.org /f/fu/fungus.html (1101 words)

	Borchsenius, A.S. - Antisuppressor effect of mutants with impaired karyogamy in Saccharomyces cerevisiae. (Site not responding. Last check: 2007-10-09)
		Borchsenius, A.S. - Antisuppressor effect of mutants with impaired karyogamy in Saccharomyces cerevisiae.
		Antisuppressor effect of mutants with impaired karyogamy in Saccharomyces cerevisiae.
		Mutants with defect in karyogamy and increased translation fidelity simultaneously (HfcAsu-mutants) suggest connection between translation termination and cell processes in yeast.
	www.yeastgenome.org /community/meetings/yeast96/f3020.html (207 words)

	Plasmodiphorid Home Page (Site not responding. Last check: 2007-10-09)
		Although meiosis has been extensively documented during cleavage of transitional sporogenic plasmodia into resting spores, location of karyogamy in plasmodiophorid life cycles remains a problem and merits further research.
		Several publications have interpreted some light and/or transmission electron microscopic images of nuclei close together as evidence for karyogamy, but Braselton (1995) questioned whether karyogamy was conclusively observed, which was consistent with Karling's (1968, page 28) summary of our knowledge of sexuality in plasmodiophorids: ".
		Kole's article (1954, page 14) summarized observations of fusion of zoospores, and pointed out that karyogamy was not observed in fused zoospores.
	oak.cats.ohiou.edu /~braselto/plasmos/fert.html (135 words)

	Interaction of the yeast gamma -tubulin complex-binding protein Spc72p with Kar1p is essential for microtubule function ... (Site not responding. Last check: 2007-10-09)
		Karyogamy efficiency was determined as described in Materials and methods.
		Amino acids 106-192 of Kar1p (green) are involved in karyogamy, whereas the C-terminal domain (red and blue) containing the hydrophobic membrane anchor (blue) is essential for SPB duplication and for the localization of Kar1p to the half bridge of the SPB (Vallen et al., 1992
		Karyogamy efficiency of wild-type and mutant cells was determined as described in Materials and methods.
	embojournal.npgjournals.com /cgi/content/full/18/15/4180 (7389 words)

	Sequential involvement of Cdk1, mTOR and p53 in apoptosis induced by the HIV-1 envelope
		Representative fluorescence micrographs of Hoechst 33342-counterstained syncytia exhibiting cytoplasmic fusion without nuclear fusion ('pre-karyogamy'), nuclear fusion without apoptosis ('karyogamy') and nuclear fusion with apoptosis are shown.
		Figure 3 Involvement of Cdk1 in karyogamy and apoptosis.
		(I) Karyogamy triggered by microinjection of cyclin B−Cdk1.
	www.nature.com /emboj/journal/v21/n15/fig_tab/7594613ft.html (1629 words)

	Summary (Site not responding. Last check: 2007-10-09)
		Sexual reproduction involves the conjugation of hyphae (plasmogamy), although karyogamy (nuclear fusion) is usually delayed with the life cycle of many fungi including a prolonged dikaryotic stage.
		When it finally occurs, karyogamy is usually followed immediately by meiosis.
		Karyogamy and meiosis within a basidium produce externally borne, haploid basidiopores.
	www.mcgraw-hill.com.au /mhhe/biology/knox2e/stu/Ch36summary.htm (770 words)

	Huddler, Donald P - KAR8 is a dnaJ homolog that is involved in karyogamy. (Site not responding. Last check: 2007-10-09)
		Huddler, Donald P - KAR8 is a dnaJ homolog that is involved in karyogamy.
		KAR8 is a dnaJ homolog that is involved in karyogamy.
		Mating in the budding yeast involves several discrete phases: (1) sensing and response to mating pheromone (GPA1 and STE genes) (2) cell wall modification and zygote formation (FUS genes) (3) nuclear congression (class I KAR genes) and (4) nuclear envelope fusion (class II KAR genes).
	www.yeastgenome.org /yeast96/f2345.html (265 words)

	Sequential involvement of Cdk1, mTOR and p53 in apoptosis induced by the HIV-1 envelope -- Castedo et al. 21 (15): 4070 ... (Site not responding. Last check: 2007-10-09)
		phosphorylation correlates with karyogamy in syncytia elicited by HIV-1 Env
		Syncytia were generated on unpatterned substrates or on specialized culture substrates designed to increase cellular spreading and syncytial size (5/10 SAM) or to exert an external constraint on cell size (square-shaped SAM 20 µM in diameter).
		Ferri,K.F., Jacotot,E., Geuskens,M. and Kroemer,G. (2000b) Apoptosis and karyogamy in syncytia induced by HIV-1–ENV/CD4 interaction.
	embojournal.npgjournals.com /cgi/content/full/21/15/4070 (5858 words)

	Fundació Irsicaixa
		Syncytia arising from the fusion of cells expressing the HIV-1-encoded Env gene with cells expressing the CD4/CXCR4 complex undergo apoptosis following the nuclear translocation of mammalian target of rapamycin (mTOR), mTOR-mediated phosphorylation of p53 on Ser15 (p53(S15)), p53-dependent upregulation of Bax and activation of the mitochondrial death pathway.
		Karyogamy is secondary to a transient upregulation of cyclin B and a mitotic prophase-like dismantling of the nuclear envelope.
		Peripheral blood mononuclear cells from HIV-1-infected patients exhibit an increase in cyclin B and mTOR expression, correlating with p53(S15) phosphorylation and viral load.
	www.irsicaixa.org /english/research/abstract.php3?codigo=193 (170 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		Karyogamy is the fusing of the two nuclei, and is immediately followed by meiosis.
		The diploid cells produced by karyogamy, are basidia basidia.
		The basidiocarps, emerging from the mycelium are where karyogamy takes place in basidiomycetes.
	www.personal.psu.edu /students/a/t/atw5003/unique.html (299 words)

	LiAbstract (Site not responding. Last check: 2007-10-09)
		Using spread preparations of meiotic nuclei, we confirmed previous studies that showed that at six hours post-karyogamy essentially all meiotic nuclei are in pachytene.
		We found that homolog pairing occurs rapidly after karyogamy, that a 1 Mb chromosome does not associate more quickly than a 2.5 Mb chromosome, and that interstitial, single copy sites can associate stably prior to nucleolar fusion.
		Analysis of two probes for the same pair of homologs revealed that by four hours after karyogamy each chromosome examined was at least partially paired in all meiotic cells.
	sunflower.bio.indiana.edu /~mzolan/Oldzolan/zolanlab/LiAbst.html (129 words)

	Fission Yeast Mutants Affecting Telomere Clustering and Meiosis-Specific Spindle Pole Body Integrity -- Jin et al. 160 ...
		Distribution pattern of Taz1::GFP and Sad1 in meiotic cells of WT and dot mutants during karyogamy or horsetail stages.
		A wild-type meiotic cell is shown in the karyogamy stage before nuclear fusion (A), in the horsetail stage (B), in meiosis I (C), in meiosis II (D), and in the sporulation stage (E).
		In the dot1-182 mutant, 25% of cells in meiosis II have spindle defects as shown in F–H. The most typical and severe defect is the absence of microtubule bundles around the four daughter nuclei after meiosis II (I).
	www.genetics.org /cgi/content/full/160/3/861 (7201 words)

	Fungusoverview
		Plasmogamy occurs forming dikaryotic zygosporangium, inactive and resistant to desiccation and freezing.
		When conditions change karyogamy occurs and haploid recombined spores are released.
		Karyogamy in the terminal cells of the gills produce diploid basidia.
	users.rcn.com /rpohlman/fungusoverview.htm (569 words)

	A Novel Fission Yeast Gene, tht1+, Is Required for the Fusion of Nuclear Envelopes during Karyogamy -- Tange et al. 140 ... (Site not responding. Last check: 2007-10-09)
		A Novel Fission Yeast Gene, tht1+, Is Required for the Fusion of Nuclear Envelopes during Karyogamy -- Tange et al.
		We have been interested in the karyogamy in Schizosaccharomyces pombe, because cytological studies have proven it to be an
		a karyogamy gene, is the yeast homolog of the mammalian Bip/GRP78
	www.jcb.org /cgi/content/full/140/2/247 (7214 words)

	Sexual Structure Questions
		Plasmogamy is immediately followed by karyogamy, followed by meiosis.
		In the remaining fungi, plasmogamy need not be followed immediately by karyogamy.
		Further, karyogamy need not be followed immediately by meiosis.
	bugs.bio.usyd.edu.au /Mycology/Reprodn_Dispersal/questions/sexualStructQ.html (365 words)

	Untitled Document (Site not responding. Last check: 2007-10-09)
		These are either saprophytic or parasitic and digest food extracellularly; cell walls of chitin; predominately haploid with plasmogamy and karyogamy often separated in time resulting in the occurrence of a persistent dikaryotic stage.
		an ascus with ascospores; also hyphae cellular with incomplete septations, asexual reproduction often by conidia, plasmogamy and karyogamy separated in time resulting in a dikaryotic stage.
		Blue mold; the source of penicillin, gives blue cheese its color, produces an abundance of conidia resulting in its blue color; be able to recognize conidia and conidiophores, be able to interpret questions reflecting your understanding of the organism's life cycle
	botit.botany.wisc.edu /courses/botany_130/Div/Fungi.html (200 words)

	PROTOZOA - LoveToKnow Article on PROTOZOA (Site not responding. Last check: 2007-10-09)
		Hence true syngamy may be distinguished as karyogamy from the process of plastogamy, or fusion of the protoplasmic bodies, of frequent occurrence in many forms of Protozoa.
		True syngamy consists, as has been said, of nuclear fusion or karyogamy.
		It rarely, if ever, happens, however, that such fusion takes place without the conjugating nuclei having undergone some process of reduction by elimination of a portion of the nuclear substance, in a manner analogous to the maturation of the germ-cells in the Metazoa.
	43.1911encyclopedia.org /P/PR/PROTOZOA.htm (10571 words)

	Fungi (Site not responding. Last check: 2007-10-09)
		Hyphae are the filamentous cells or linked-together cells that represent the bulk of the bodies of molds and macrofungi (e.g., mushrooms)
		Karyogamy (a process) (= fusion of haploid nuclei)
		The fusion of haploid nuclei found in dikaryonic fungal cells is called karyogamy
	www.mansfield.ohio-state.edu /~sabedon/campbl31.htm (723 words)

	ICPP98 Paper Number 1.8.15 (Site not responding. Last check: 2007-10-09)
		Previously, we have observed karyogamy within 2 weeks in heterokaryons formed by hyphal anastomosis.
		We have used a battery of genetic and molecular markers including auxotrophy, allozymes, electrophoretic karyotyping and amplified fragment length polymorphisms (AFLP) to investigate the formation of intra- and inter-VCG heterokaryons by both hyphal anastomosis and protoplast fusion.
		We are investigating the time course of karyogamy in heterokaryons formed by protoplast fusion, through allozyme and AFLP analysis of the uninuclear microconidia of the heterokaryons.
	www.bspp.org.uk /icpp98/1.8/15.html (419 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations (Site not responding. Last check: 2007-10-09)
		Posttranscriptional regulation of the karyogamy gene by Kem1p/Xrn1p exoribonuclease and Rok1p RNA helicase of Saccharomyces cerevisiae
		Mutational analysis has shown that Kem1p/Xrn1p participates in microtubule-related functions such as nuclear fusion (karyogamy) during mating, chromosome transmission, and spindle pole body duplication.
		Here, evidence is presented that Kem1p plays a specific role in nuclear fusion by affecting, at the posttranscriptional level, the pheromone induction of the karyogamy-specific transcription factor Kar4p and the expression of Rok1p, a putative RNA helicase.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=20606672 (285 words)

	Untitled Document (Site not responding. Last check: 2007-10-09)
		These are either saprophytic or parasitic and digest food extracellularly; no flagella; cell walls of chitin; predominately haploid with plasmogamy and karyogamy often separated in time resulting in the occurrence of a persistent dikaryotic stage.
		Know four types of hyphae and be able to recognize a zygosporangium and to interpret questions in light of your knowledge of the life cycle.
		Blue mold; the source of penicillin, gives blue cheese its color, produces an abundance of conidia resulting in its blue color; be able to recognize conidia and conidiophores.
	botit.botany.wisc.edu /courses/Botany_130/Div/fungi/Fungi.html (327 words)

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