A performance-based cost to honest signalling in male green anole lizards (Anolis carolinensis)

Sexual signals are considered costly to produce and maintain under the handicap paradigm, and the reliability of signals is in turn thought to be maintained by these costs. Although previous studies have investigated the costly nature of signal production, few have considered whether honesty might be maintained not by the costliness of the signal itself, but by the costs involved in producing the signalled trait. If such a trait is itself costly to produce, then the burden of energetic investment may fall disproportionately on that trait, in addition to any costs of signal maintenance that may also be operating. Under limited resource conditions, these costs may therefore be great enough to disrupt an otherwise reliable signal-to-trait relationship. We present experimental evidence showing that dietary restriction decouples the otherwise honest relationship between a signal (dewlap size) and a whole-organism performance trait (bite force) in young adult male Anolis carolinensis lizards. Specifically, while investment in dewlap size is sustained under low-resource condition relative to the high-resource treatment, investment in bite force is substantially lower. Disruption of the otherwise honest dewlap size to bite force relationship is therefore driven by costs associated with the expression of performance rather than the costs of signal production in A. carolinensis.     

SIBLING SPECIES,CALL DIFFERENCES,AND SPECIATION IN GREEN LACEWINGS (NEUROPTERA: CHRYSOPIDAE: CHRYSOPERLA)

Green lacewings of the morphologically homogeneous carnea-plorabunda-downesi group within the chrysopid genus Chrysoperla produce unique, species-specific, substrate-borne songs during courtship and mating; both sexes sing, and partners must reciprocally exchange their acoustical signals before copulation will occur. Two widespread, sympatric North American representatives of this complex, the sibling species pair C. plorabunda and C. downesi, hybridize readily in the laboratory but not in nature. This species pair has been presented as exemplifying sympatric speciation by disruptive selection. Here, it is shown from tape-playback and female-choice experiments that calls represent bona fide reproductive isolating mechanisms between the two species. Furthermore, call analyses of F₁, F₂, F₃, and backcross progeny of the two species confirm polygenic control of call expression, in which different alleles at each of several loci are fixed in each taxon. Sex linkage of traits is absent, but the various features of the calls are not completely independent of one another in their patterns of inheritance. These and other life-history data cast doubt on several major premises of the sympatric speciation hypothesis and suggest that call alteration might have triggered the speciation event giving rise to the siblings. A complex of cryptic “song morphs” physically and ecologically identical to C. plorabunda and C. downesi, but singing different songs, exists in the mountains of western North America, while the Alps of central Europe harbor populations of C. carnea that have undergone call differentiation in an analogous but independent manner. It is proposed that call divergence may in itself be driving the speciation process within this section of Chrysoperla, by greatly accelerating the rate at which full reproductive isolation between populations can be achieved.     

LIGHT-HARVESTING PIGMENT-PROTEIN COMPLEXES OF THE ULVOPHYCEAE (CHLOROPHYTA):CHARACTERIZATION AND PHYLOGENETIC SIGNIFICANCE1

Photosystem II light-harvesting complexes were isolated from a number of ulvophycean algae. Some of these light-harvesting complexes displayed unusual features, most notably a high apparent molecular weight (ca. 58,000) when isolated by lithium doderyl sulfate polyarrylamide gel electrophoresis. Other ulvophycean light-harvesting complexes had a low-molecular weight (ca. 30,000). The distribution of the high-molecular weight complex was limited to certain members of the Caulerpales and Blastophysa rhizopus (Siphanocladales). Within the Caulerpales, there were also spectral differences between the high-molecular weight and low-molecular weight light-harvesting complex types. The differences in light-harvesting complexes in the Ulvophyceae suggest that there are two lines of evolution in the Caulerpales and that Blastophysa may be an intermediate between the Siphon-ocladales and the Caulerpales.     

Cell adhesion: More than just glue (Review)

The ability of cells to interact with each other and their surroundings in a co-ordinated manner depends on multiple adhesive interactions between neighbouring cells and their extracellular environment. These adhesive interactions are mediated by a family of cell surface proteins, termed cell adhesion molecules. Fortunately these adhesion molecules fall into distinct families with adhesive interactions varying in strength from strong binding involved in the maintenance of tissue architecture to more transient, less avid, dynamic interactions observed in leukocyte biology. Adhesion molecules are extremely versatile cell surface receptors which not only stick cells together but provide biochemical and physical signals that regulate a range of diverse functions, such as cell proliferation, gene expression, differentiation, apoptosis and migration. In addition, like many other cell surface molecules, they have been usurped as portals of entry for pathogens, including prions. How the mechanical and chemical messages generated from adhesion molecules are integrated with other signalling pathways (such as receptor tyrosine kinases and phosphatases) and the role that aberrant cell adhesion plays in developmental defects and disease pathology are currently very active areas of research. This review focuses on the biochemical features that define whether a cell surface molecule can act as an adhesion molecule, and discusses five specific examples of how cell adhesion molecules function as more than just 'sticky’ receptors. The discussion is confined to the signalling events mediated by members of the integrin, cadherin and immunoglobulin gene superfamilies. It is suggested that, by controlling the membrane organization of signalling receptors, by imposing spatial organization, and by regulating the local concentration of cytosolic adapter proteins, intercellular and cell-matrix adhesion is more than just glue holding cells together. Rather dynamic ‘conversations’ and the formation of multi-protein complexes between adhesion molecules, growth factor receptors and matrix macromolecules can now provide a molecular explanation for the long-observed but poorly understood requirement for a number of seemingly distinct cell surface molecules to be engaged for efficient cell function to occur.     

ISOLATION AND CHARACTERIZATION OF A VIRUS INFECTING PHAEOCYSTIS POUCHETII (PRYMNESIOPHYCEAE)1

A virus infecting the haptophyte Phaeocystis pouchetii (Hariot) Lagerheim was isolated from Norwegian coastal waters in May 1995 at the end of a bloom of this phytoplankter. The virus was specific for P. pouchetii because it did not lyse 10 strains of P. globosa Scherffel, Phaeocystis sp., and P. antarctica Karsten. It was a double-stranded DNA virus, and the viral particle was a polyhedron with a diameter of 130–160 nm. The virus had a main polypeptide of about 59 kDa and at least five minor polypeptides between 30 and 50 kDa. The latent period of the virus when propagated in cultures of P. pouchetii was 12–18 h, and the time required for complete lysis of the cultures was about 48 h. The burst size was estimated to be 350–600 viral particles per lysed cell.     

ISOLATION AND PARTIAL CHARACTERIZATION OF NITRATE ASSIMILATION MUTANTS OF DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE)1

Fifteen nitrate assimilation-deficient mutants of the euryhaline green alga, Dunaliella tertiolecta Butcher were selected by their chlorate resistance. Ten mutants, unable to grow on NO₃^? but able to grow on NO₂^?, had no detectable nitrate reductase activity. Five mutants, unable to grow on either NO₃^? or NO₂^?, had depressed levels of both nitrate and nitrite reductase. A method for assaying methyl viologen-nitrate reductase in the presence of nitrite reductase is described.     

商陆根中抗真菌蛋白的分离和特性研究

从美洲商陆(Phytolacca americana L.)夏天采集的2—4年生宿根中分离了二种抗真菌蛋白,称为PAFP-R_1和PAFP-R_2。分离程序包括用盐溶液提取,经CM-Sephadex离子交换层析、凝胶过滤层析和羟基磷灰石柱层析纯化。在PGA培养基上,0.1mg/ml蛋白明显抑制木霉菌丝的生长;但对细菌的增殖,即使1mg/ml也无抑制作用。用SDS-PAGE测得二者的相对分子量各为13kD和15kD,单多肽链,等电点约为5.8。用酚-硫酸法未测出含糖。二种蛋白均高含半胱氨酸(19mol/mol)。用Edman降解法测得二者的N末端均为Ala。秋天采集的根中,这二种蛋白含量均很低,但富含由二条PAFP-R_1肽链以双硫键联结的二聚体,它无抗真菌活性。冬天宿根中抗真菌蛋白主要成分是Mr为17kD的单肽链蛋白。上述蛋白对于人红血球均无凝集活性,因此不是PWM的成分。以上结果说明,商陆根中有多种具抗真菌活性的蛋白,成分随季节发生变化,它们都是不含糖,高含半胱氨酸,分子量小于20kD的单肽链蛋白。     

ISOLATION AND CHARACTERIZATION OF DOMINANT TUNICAMYCIN RESISTANCE MUTATIONS IN CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE)1

Seven independent mutations that confer resistance to the nucleoside antibiotic tunicamycin in the unicellular green alga Chlamydomonas reinhardtii were isolated in wild-type diploid cells. Upon resolution to haploidy, all the mutations segregated as single mutations and were semi-dominant when retested in heterozygous diploids. In addition, the TUN1-3 allele affects the ability of cells to agglutinate during conjugation in the absence of tunicamycin. The seven mutations map to a single locus on linkage group VIII. These mutations may be useful as a selectable marker in transformation studies of Chlamydomonas and in studies of processes that require asparagine-linked glycosylation.     

ISOLATION AND CHARACTERIZATION OF SIX cDNAs INVOLVED IN CARBON METABOLISM IN LAMINARIA DIGITATA (PHAEOPHYCEAE)

An expressed sequence tag (EST) approach was used to retrieve cDNA clones involved in carbon metabolism in Laminaria digitata Lamouroux. Six partial open reading frames were identified, respectively encoding an α-type carbonic anhydrase (CA), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), phosphoglycerate kinase (PGK), glycolate oxidase (GLO), and GDP-4-keto-6-d-mannose-3,5-epimerase-4-reductase, also known as fucose synthase (FS). These enzymes were further characterized through Southern blot analyses, amino acid sequence comparisons, and patterns of expression. In contrast to the other genes, which are expressed in both the gametophytic and sporophytic generations of L. digitata, the α-type carbonic anhydrase messenger RNA was shown by RT-PCR and northern blot analyses to be present in the gametophytes only. The evolutionary relationships of these genes and their interest as molecular tools for investigating carbon fluxes in brown algae are discussed.     

Interaction of Bcl-2 with the Autophagy-related GABAA Receptor-associated Protein (GABARAP): BIOPHYSICAL CHARACTERIZATION AND FUNCTIONAL IMPLICATIONS*

Apoptosis and autophagy are fundamental homeostatic processes in eukaryotic organisms fulfilling essential roles in development and adaptation. Recently, the anti-apoptotic factor Bcl-2 has been reported to also inhibit autophagy, thus establishing a potential link between these pathways, but the mechanistic details are only beginning to emerge. Here we show that Bcl-2 directly binds to the phagophore-associated protein GABARAP. NMR experiments revealed that the interaction critically depends on a three-residue segment (EWD) of Bcl-2 adjacent to the BH4 region, which is anchored to one of the two hydrophobic pockets on the GABARAP molecule. This is at variance with the majority of GABARAP interaction partners identified previously, which occupy both hydrophobic pockets simultaneously. Bcl-2 affinity could also be detected for GEC1, but not for other mammalian Atg8 homologs. Finally, we provide evidence that overexpression of Bcl-2 inhibits lipidation of GABARAP, a key step in autophagosome formation, possibly via competition with the lipid conjugation machinery. These results support the regulatory role of Bcl-2 in autophagy and define GABARAP as a novel interaction partner involved in this intricate connection.     

棕尾别麻蝇幼虫肠道溶纤活性蛋白酶的分离纯化和性质

从以富含纤维蛋白的血凝块为食物的棕尾别麻蝇幼虫肠道浸提液中分离纯化出3种具有溶纤活性的蛋白酶,分别命名为BPGFP1,BPGFP2和BPGFP3。其中,BPGFP1由两个分子量分别为32000和30000的亚基组成。BPGFP2和BPGFP3均为单体,分子量分别为40000和28000。这三种蛋白酶具有相似的底物特异性和抑制剂特性。三种蛋白酶均能降解溶纤活性蛋白酶的特异底物纤维蛋白,Chromzym,P,Chromzym UK和S－2288。三种酶还能够强烈降解类胰蛋白酶专一底物Bz-Phe-Val Arg NA,cBz Gly-Pro-Arg NA,Bz-Pro－Phe-Arg NA和Bz-Val-Gly-Arg NA.PMSF,STI,LBTI和SBBI能够对三种蛋白酶活怀有极强的抑制作用。三种溶纤活性蛋白酶均在pH9.0-10.0范围内表现出较高活性。     

嗜热真菌Thermomyces lanuginosus A_(236)热稳定葡萄糖淀粉酶的纯化及其特性

嗜热真菌ThermomyceslanuginosusA_236在液体培养基中50℃下静止培养14天,粗提酶液经硫酸铵分级沉淀、DEAE-Toyopearl离子交换层析、Butyl－Toyopearl疏水层析、SephacrylS100凝胶过滤和FPLCMonoQ离子交换层析,得到了凝胶电泳均质的葡萄糖淀粉酶。酶促反应产物经TLC分析为葡萄糖,证明纯化的酶为葡萄糖淀粉酶（EC3．2．1．3）。SDS－PAGE测定其分子量为72,000,不具亚基,PI为4．0,富含Val和Leu。酶反应最适温度和pH分别为70℃和5．0。在pH5．0条件下,酶在60℃保温1h,仍具有原酶活性。酶活性在70℃和80℃的半衰期分别为20min和6min。Ca2+对酶有激活作用,Fe3+、Al3+、Hg2+等金属离子对酶活力有一定的抑制作用。纯酶碳水化合物含量为12．4％。纯酶可水解可溶性淀粉、直链淀粉、支链淀粉、糊精、糖原、麦芽三糖和麦芽糖,其中可溶性淀粉为最适底物。     

Parent-absent begging: evidence for sibling honesty and cooperation in the spotless starling (Sturnus unicolor)

Begging in avian nestlings is a highly conspicuous behaviorwith important implications for the study of parent–offspringconflict. In some species, nestlings also call for long boutsin the absence of parents, and it has been proposed that thisbehavior is used by nestlings as a means of negotiating accessto food. We studied this phenomenon in the spotless starling(Sturnus unicolor). We found that parent-absent calls were acousticallydistinct from parent-present calls. Observations showed thatthe probability of parent-absent begging increased with nestlingage and brood size, whereas it decreased with increasing bodycondition. This result was confirmed by an experiment that showedthat nestlings produced higher parent-absent begging rates whenfood deprived than when satiated. Finally, we carried out aplayback experiment to test the reaction of nestlings to parent-absentbegging by fellow nestlings. Principle components analyses yielded2 independent components of begging: 1) a general begging componentand 2) a second factor that measures the relative contributionof communicative begging over competitive begging. Nestlingsexposed to playback decreased their general begging levels andsimultaneously increased the relative contribution of communicativeover competitive begging. This behavior may favor needy nestlingsto obtain impending feedings while keeping high levels of foodsolicitation from parents and is consistent with a cooperativestrategy among nestlings. Future research should consider theactual response of parents to these signals.     

PURIFICATION AND PARTIAL CHARACTERIZATION OF A GUT TRYPSIN-LIKE PROTEASE FROM LARVAE OF FLESH FLY BOETTCHERISCA PEREGRIN A (DIPTERA: SARCOPHAGAE)

Abstract A 16kD protease was purified from the gut extract of larvae of Boettcherisca peregrina , after ammonium sulfate precipitation, DEAE-Sephadex A-25 ion-exchange chromatography and SBBI-Sepharose 4B affinity chromatography. The results of substrate and inhibitor specificity indicated that the protease behaved as a trypsin-like protease. It possesses high activity against non-specific substrate casein and Hide powder azure, and against trypsin-specific substrates Bz-Phe-Val-Arg NA, Bz-Pro-Phe-Arg NA and Bz-Val-Gly-Arg NA. It can be strongly inhibited by PMSF, phenymethysulfonyl fluoride (serine protease inhibitor), SBBI, soybean Bowman-Birk inhibitor and Leupeptin (trypsin-specific inhibitor). Activity of this protease was found to be maximal at the alkaline range of pH 8. 5–9. 5.