Larval host plant affects fitness consequences of egg size variation in the seed beetle Stator limbatus

Egg size variation often has large effects on the fitness of progeny in insects. However, many studies have been unable to detect an advantage of developing from large eggs, suggesting that egg size variation has implications for offspring performance only under adverse conditions, such as during larval competition, periods of starvation, desiccation, or when larvae feed on low-quality resources. We test this hypothesis by examining the consequences of egg size variation for survivorship and development of a seed-feeding insect, Stator limbatus, on both a low-quality (Cercidium floridum) and a high-quality (Acacia greggii) host plant. Our results are consistent with the hypothesis. S. limbatus larval performance was affected by egg size only when developing on the poor-quality host (C. floridum); larvae from large eggs survived better on C. floridum than those from small eggs, while there was no evidence of an effect of egg size on progeny development time, body weight, or survivorship when larvae developed on A. greggii. These results indicate intense selection for large eggs within C. floridum-associated populations, but not in A. greggii-associated populations, so that egg size is predicted to vary among populations associated with different hosts. Our results also support this hypothesis; females from a C. floridum-associated population (Scottsdale) laid larger eggs than females from an A. greggii-associated population (Black Canyon City).     

Body size,litter size,timing of reproduction,and juvenile survival in the Unita ground squirrel,Spermophilus armatus

The timing of reproduction affected litter size, offspring mass, and offspring survival in the Uinta ground squirrel, Spermophilus armatus, in Grand Teton National Park, Wyoming. Survival of juvenile females to yearling age varied negatively with date of weaning and positively with individual offspring mass. At the same time, juveniles weaned early in the season were lighter, and juveniles weaned later in the season were heavier. The coefficient of variation for juvenile body mass, originally measured at weaning, significantly decreased by the time juveniles entered hibernation, indicating that individuals weaned early and light caught up in body mass to individuals weaned later and heavier. From the perspective of the mother's investment in the litter, litter size (corrected for mother's mass) decreased with later wcaning dates, while the relationship of weaning date to litter mass (corrected for mother's mass) was significant in only one year. Maternal allocation of resources in litters changed over the season so that mothers produced many, small offspring early in the season, and fewer, large offspring late in the season.     

Determination of two sites of automethylation in bovine erythrocyte protein (d -aspartyl/l -isoaspartyl) carboxyl methyltransferase

Protein (d-aspartyl/l-isoaspartyl) carboxyl methyltransferase (PCM, E.C. 2.1.1.77) was previously shown to be enzymatically methyl esterified in an autocatalytic manner at altered aspartyl residues; methyl esters are observed in a subpopulation of the enzyme termed thePCM fraction [Lindquist and McFadden (1994),J. Protein Chem. 13, 23–30]. The altered aspartyl sites serving as methyl acceptors inPCM have now been localized by using proteolytic enzymes and chemical cleavage techniques in combination with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to identify fragments of the [³H]automethylated enzyme that contain a [³H]methyl ester. Methylation was positively identified at positions Asn₁₈₈ and Asp₂₁₇ in the enzyme sequence, a consequence of the spontaneous alteration of these sites tol-isoaspartyl ord-aspartyl sites and their methylation by active PCM molecules. The identification of more than one site of automethylation shows thatPCM is not a homogeneous population of damaged PCM molecules, but rather a complex population of molecules with a variety of age-altered damage sites.Abbreviations PCM protein (d-aspartyl/l-isoaspartyl) carboxyl methyltransferase - EDTA disodium ethylenediaminetetraacetate - PMSF phenylmethylsulfonyl fluoride - TEA trifluoroacetic acid - HPLC high-pressure liquid chromatography     

Halcyon days with Bill Arnold

The circumstances that led to the discovery that plants luminesce after they are illuminated are described, as are other discoveries that would not have been possible were it not for the fortuitous association I had with my dear and most admirable friend, W.A. Arnold, to whom this special issue is dedicated.     

Studies on the development and three-dimensional reconstruction of giant mitochondria and their nuclei in egg cells ofPelargonium zonale Ait.

Summary The preferential development of giant mitochondria and their nuclei (nucleoids) in the egg cells ofPelargonium zonale Ait. during megasporogenesis and megagametogenesis was examined by fluorescence microscopy, after Technovit embedding and 4,6-diamidino-2-phenylindole (DAPI) staining, fluorimetry for DNA content, using a video-intensified microscope photon-counting system (VIMPICS), and by three-dimensional reconstruction of mitochondrial nuclei (mt-nuclei). Reproductive cells during the megaspore mother cell, meiosis, tetrad, and functioning megaspore stages contained many small mitochondria with characteristic, uniformly DAPI-stained mt-nuclei about 0.3 m in diameter, containing a small amount of DNA (0.3 Mbp). During formation of the 2-, 4-, and 8-nucleate embryo sac, mt-nuclei did not markedly change in shape or DNA content. When the embryo sac formed and differentiation of each cell began, mitochondria and their nuclei in the egg cell took on a small ring or string-like shape. Accompanying the maturation of the embryo sac, they underwent progressive enlargement and gradually altered to long thick strings, or stacks of concentric or half concentric rings. By flower opening, they have developed to an extremely large size. One of these stacks of mt-nuclei was reconstructed in three dimensions; each ring in the stack was cup- or plate-shaped; 5 to 10 rings made up the stack, though each remained discontinuous from the others. From serial sections, we counted 44 mitochondria in one egg cell. Fluorometry using VIMPICS revealed that DNA amount within the stacked mitochondrion increased to 40 times that of the megaspore mother cell stage; a single stack of mitochondria contained 340–1700 Mbp DNA; which means that one egg cell contains at least 15000 Mbp mt-DNA, a value greater than the cell-nuclear DNA content.     

Rapid authentication of animal cell lines using pyrolysis mass spectrometry and auto-associative artificial neural networks

Summary Pyrolysis mass spectrometry (PyMS) was used to produce biochemical fingerprints from replicate frozen cell cultures of mouse macrophage hybridoma 2C11-12, human leukaemia K562, baby hamster kidney BHK 21/C13, and mouse tumour BW-O, and a fresh culture of Chinese hamster ovary CHO cells. The dimensionality of these data was reduced by the unsupervised feature extraction pattern recognition technique of auto-associative neural networks. The clusters observed were compared with the groups obtained from the more conventional statistical approaches of hierarchical cluster analysis. It was observed that frozen and fresh cell line cultures gave very different pyrolysis mass spectra. When only the frozen animal cells were analysed by PyMS, auto-associative artificial neural networks (ANNs) were employed to discriminate between them successfully. Furthermore, very similar classifications were observed when the same spectral data were analysed using hierarchical cluster analysis. We demonstrate that this approach can detect the contamination of cell lines with low numbers of bacteria and fungi; this approach could plausibly be extended for the rapid detection of mycoplasma infection in animal cell lines. The major advantages that PyMS offers over more conventional methods used to type cell lines and to screen for microbial infection, such as DNA fingerprinting, are its speed, sensitivity and the ability to analyse hundreds of samples per day. We conclude that the combination of PyMS and ANNs can provide a rapid and accurate discriminatory technique for the authentication of animal cell line cultures.     

用生物素化重组质粒探针检测产蛋下降综合症病毒核酸

用ＥＤＳ－７６标准毒株感染鸭胚后,提取病毒核酸,经ＰｓｔＩ酶切后,与质粒ｐＴ７／Ｔ３α－１９重组,并转化到大肠杆菌ＤＨ５α中,筛选出一个插入片段为３１８ｂｐ的重组质粒,并命名为ｐＴＥＺＰ３。用生物素标记该重组质粒后,分别对正常鸭胚尿囊液、各地分离的ＥＤＳ毒株和禽类易感的几种病毒进行核酸杂交试验,结果该探针对实验中收到的几种ＥＤＳ分离毒均产生阳性反应,而不与正常鸭胚尿囊液和其它几种禽类病毒交;该探针     

Dominance, competition, and energetic reserves in the European starling, Sturnus vulgaris

We investigated the relationships between social dominance,competition for food, and strategies of body mass and fat regulationin the European starling (Sturnus vulgaris). In birds housedin groups of three, subdominant birds stored more fat than dominants.A removal experiment established a causal link between socialdominance and fat reserves; in groups that had the dominantindividual removed, the remaining birds reduced body mass andfat, relative to control groups that had the subordinate removed.In a second experiment, we investigated the influences of degreeof competition for food and dominance on body mass and fat reserves.Birds under high competition increased fat reserves and tendedto have higher body mass than birds under low competition. Theincrease in fat reserves was higher in the subdominants thanin the dominants. These results are consistent with hypothesesconcerning dominance-dependent access to food; subdominant birds,or birds under increased competition, may store more fat asan insurance against periods when food cannot be obtained. However,relations between dominance, body mass, and fat reserves mayalso arise through other proximate factors relating to dominance-dependentcosts and benefits of fat storage, such as predation risk andenergetic expenditure.     

Litter fall and decomposition in a Pinus halepensis forest on Mallorca

Abstract. Litter fall and decomposition in a Pinus halepensis forest was studied in order to help understand nutrient cycles in this ecosystem, threatened as it is by fire and tourism. The study was done over two years in an experimental forest stand at Cap des Pinar on Mallorca, Spain. The woodland area has not been disturbed for about 40 yr. Total litter fall amounted to 3.44 ton ha^-1 yr^-1 and 2.52 ton ha^-1 yr^-1 in the first and second year, and leaf fall to 2.00 ton ha^-1 yr^-1 and 1.93 ton ha^-1 yr^-1 respectively with a maximum in July. As to litter fall, there was a summer maximum for brown needles and kernels, a spring maximum for inflorescences and bud scales, and an autumn maximum for bark. Erratic maxima occurred for fall of green needles, cones and branches, linked to strong winds in winter. The total amount of litter mass on the forest soil reached 12.68 ton/ha: 5.75 ton/ha in the L organic horizon, 3.46 ton/ha needles, and 6.93 ton/ha in the F organic horizon. Weight loss from annual decomposition, measured using litter bags, was 18.1 % in year 1 and 26.8% in year 2. Over 365 days, an Olson (1963) decomposition rate of 0.045 %/day was found in year 1 and of 0.084 %/day for year 2. Decomposition half-time was 1529 for year 1 and 827 days for year 2.     

Application of the multiple antigenic peptides (MAP) strategy to the production of prophormone convertases antibodies: Synthesis,characterization and use of 8-branched immunogenic peptides

Antiserum against an N-terminal sequence of murine prohormone convertase-1 (mPC1) incorporating the sequence immediatley following the junction between the putative pro-region and the active enzyme was obtained. This was accomplished using the multiple antigenic peptide (MAP) approach whereupon an 8-branched polylysine core to which are grafted multiple copies of a 16 amino acid peptide representing the N-terminal sequence of mPC1 (positions 84–99) was synthesized by solid-phase Fmoc chemistry. The ensuing peptide was purified and fully characterized by RP-HPLC, ¹H-NMR, amino acid composition, peptide sequencing and ion-spray mass spectrometry. The immunological properties of the resulting antibodies in detecting recombinant PC1 in both crude and purified preparations were compared with antibodies raised against a similar N-terminal segment of PC1 but using the conventioanl method of peptide–carrier protein conjugation and also developed against a C-terminal fusion protein of PC1. Our data indicate that the MAP antibody was as efficient as both the amino and carboxy-terminal antibodies in qualitative as well as quantitative analysis of PC1 encoded protein by radioimmunoassay. Following an identical approach, antibodies against other prohormone convertases like furin, PC5/6 and PACE4 were also developed and subsequently applied to a number of biochemical and immunological studies. In each case, the ease of preparation and high immunogenicity of the MAP approach were confirmed and reside in the simplicity and rapidity with which a potent and useful antiserum is obtained.