The effect of fixatives in the quantification of morphological lipofuscin as an age index in crustaceans

The role of fixation in studies using histological techniques to measure lipofuscin as an age indicator was evaluated. Four fixatives were used: Bouin, 10% buffered saline formaldehyde, Davidson and San Felice. The species used was the Norway lobster (Nephrops norvegicus). Similar sized males, with a maximum carapace length difference of less than 10 mm were used and attributed randomly to each treatment. Results showed that San Felice and Davidson were not appropriate for lipofuscin studies. Bouin and 10% formaldehyde produced the best results in terms of tissue quality and lipofuscin granule brightness. This work suggests that Bouin can be a substitute of formaldehyde in lipofuscin studies, in particular in situations when other structures, such as gonads, are needed for parallel or complementary studies.     

用蝶啶荧光分析法推断大头金蝇成虫日龄

应用蝶啶荧光分析法分析了常见尸食性蝇类大头金蝇Chrysomyamegacephala成虫头部蝶啶含量与日龄间关系 ,以及温度、性别等对这种关系的影响。结果表明 ,日龄、温度和性别对成虫蝶啶含量均有显著影响 ,其中温度为主要影响因子。在 16℃、2 0℃、2 4℃、2 8℃和 32℃各恒温下 ,成虫头部蝶啶含量与日龄间存在显著的线性关系。雌雄成虫头部蝶啶积累速率 (或 )与温度 (t)的关系分别可用指数函数FV =0 0 12 88×e(0 2 2 41t-3 12 7) +0 36 49(r2 =0 9987)和线性函数MV =0 0 5 74t- 0 36 37(r2 =0 95 5 7)很好地加以拟合。依据恒温试验结果 ,提出了自然变温条件下成虫日龄的 3种候选估测方法 ,证实这 3种方法仅适宜雄成虫而不适于雌成虫 ,其中对雄成虫日龄估测的最小误差平均为 2 5 5d。最后实际应用中如何选用这 3种方法作了讨论。     

Lipofuscin-like fluorophores originated from malondialdehyde

The accumulation of fluorescent age pigment or lipofuscin is a frequently observed age-associated cellular alteration in a variety of post-mitotic cells of many species. These pigments are observed within granules composed, in part, of damaged protein and lipid. In the present mini-review, I provide a comprehensive summary of fluorescent adducts originated from malondialdehyde (MDA).     

Physiological reactions to a change in light regime in cultured Skeletonema costatum (Bacillariophyta): implications for estimation of phytoplankton biomass

The marine planktonic diatom Skeletonema costatum (Cleve) was grown in batch culture under a 12 h light: 12 h dark (LD) regime for several generations before the experiment. At Time 0, half of the culture was transferred to continuous light (CL). Particulate organic carbon (POC), nitrogen (PON), and photosynthetic pigments (measured by spectrophotometry and high performance liquid chromatography) were monitored for 7 to 9 days in the two cultures. Under CL, POC and PON production were always lower. In addition, we measured a much higher proportion of chlorophyll degradation products (as chlorophyllid a, phaeophytin a and phaeophorbid a (PrD)). These indicate different physiological conditions between the two cultures, as reflected also be the lower POC/PON and chlorophyll a/POC ratios. Under CL illumination cells appear stressed, probably due to the total quantity of light to which cells are exposed. In fact, a higher proportion of the two xanthophylls diadinoxanthin and diatoxanthin in the CL culture indicates a photoprotective reaction of the cells. In contrast with the LD culture, parameters measured were not significantly inter-correlated in the CL culture. The lack of correlation between chlorophyll a and POC in CL does not encourage the use of the chlorophyll a/POC ratio as a biomass estimator. On the opposite, the ratio of total pigment content to POC did not vary much as a function of the light condition of the culture, remaining near 0.040 in both light regimes. Although further observations are needed, this index seems to be a reliable indicator of phytoplankton carbon biomass.     

Developmental changes of sepiapterin synthase activity associated with a variegated purple gene in Drosophila melanogaster

A variegated position effect on the autonomous gene, purple, has been studied enzymologically in Drosophila melanogaster. Sepiapterin synthase, the enzyme system associated with pr⁺, was examined for activity in different developmental stages of the fly. The results indicate that T(Y:2) pr^c5, cn/pr^c4 cn flies (flies in which pr⁺ has been translocated and which exhibit variegation) have a reduced amount of enzyme activity as compared with both Oregon-R and pr¹ flies. This reduction in activity was not found in larval stages, which suggests that the inactivation process probably occurs in late larval or early pupal stages. The phenotype of the variegated adult has white eyes with red-colored spots and patches where drosopterins occur. The phenotype of the fly carrying the translocation is modified by the presence of additional Y chromosomes. This extends the observation from other systems that extra heterochromatin acts to suppress the variegated position effect. The advantages of studying the variegation by measuring enzyme activity, as well as the phenotypic expression, are several; for example, the developmental time at which variegation occurs may be estimated even though drosopterin synthesis is not occurring.The Oak Ridge National Laboratory is operated by Union Carbide Corporation for the Department of Energy under Contract No. W-7405-eng-26.     

Characterisation of pigments in the head capsule of the adult stablefly Stomoxys calcitrans

The pteridines 6-biopterin and isoxanthopterin have been identified in aqueous head extracts of adult males and females of the stablefly, Stomoxys calcitrans. Levels of 6-biopterin increase linearly with age of the insect. This forms the basis of an accurate age determination technique described by Mail et al. (1983).

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Résumé Les ptéridines 6-bioptérine et isoxanthoptérine ont été identifiées dans des extraits aqueux de têtes d'adultes mâles et femelles de S. calcitrans. Les taux de 6-bioptérine augmentent linéairement avec l'âge de l'insecte. Ceci fournit la base de la technique précise de détermination de l'âge décrite par Mail et al. en 1983.

     

Dynamics of diapause recruitment in populations of the face fly, Musca autumnalis

Field populations of face flies, Musca autumnalis DeGeer (Diptera: Muscidae) were sampled serially in the late summers and autumns of 1985-96, in order to measure the dynamics of diapause development in Iowa, U.S.A. Fat body hypertrophy and ovarian development were assessed through dissection, and pteridine quantities in the fly heads were measured spectrofluorometrically to estimate their physiological and chronological ages. Published laboratory studies of diapause induction established the expectation that diapause incidence would vary over successive years with prevailing temperatures. The expectation was not met by field data. Patterns in the frequencies of hypertrophied fat body and of vitellogenic nullipars indicated that about 50% of recruited adults began developing into diapause in the second week of September in each year. Degree-day summations for each year from 1985 to 1996 suggested that the hypothetical mean optimal time for switching into diapause would be in the second week of September, because a rapidly diminishing proportion of eggs laid later would result in viable, overwintering flies. It was concluded that face flies do not use daily temperatures in late summer, but instead cue on photoperiod for diapause.     

Fluorescence properties of plasma membranes from oats and cauliflower in relation to blue light physiology

Fluorescence properties of plasma membranes from dark-grown oat shoots ( Avena saliva L. cv. Sol II) and from cauliflower inflorescences ( Brassica oleracea L.) were investigated. Along with a flavin (with a possible connection to blue light physiology), a blue fluorescing component was present. The effect of NaN₃, phenyl acetic acid (PAA), KI (flavin inhibitors) and salicylhydroxamic acid (SHAM; inhibitor of e.g. the blue light-induced cytochrome b reduction) were followed with regard to the fluorescence properties of the two components as well as with regard to the light-induced cytochrome b reduction (LIAC). A change in flavin fluorescence and LIAC occurred at about the same concentration of PAA and SHAM, while LIAC was much more sensitive to KI and NaN₃ than was the fluorescence. Rapid freezing and thawing did not change the relative fluorescence emission from the flavin and blue fluorescing component, respectively, but storage at -20°C for one or two days increased the fluorescence, especially from the latter. There did not seem to be a tight coupling between the fluorescence properties of the blue fluorescing component (spectrally similar to a pteridine) and the flavin. Therefore, no conclusions could be drawn concerning their connection in blue light physiology, i.e. in processes such as phototropism.     

Using otolith weight to age fish

The problem of determining and verifying ages of fish, from populations having a considerable variation in size at age, has been investigated using the relationship between otolith size and fish size, which has been shown by several authors to be influenced by growth rate. In such a population of Sardinella aurita Val. an index of age can be obtained for individual fish by calculating the equivalent otolith weight at a particular fish length, using the otolith weight–fish length relationship determined for each age group. This statistic not only permits a much greater proportion of fish to be assigned ages than is possible with otolith reading alone, but also enables the age groups to be verified as year classes. However, it is concluded that, although appropriate models based on otolith-fish size relationships can predict age for groups of fish in which growth rates are known or can be assumed to be consistent, such techniques have a limited application in ageing fish from wild populations with highly variable growth rates.     

Daily cuticular growth layers and the teneral stage in adult insects: A review

This paper reviews the first twenty years of progress on the occurrence and applications of daily growth layers in cuticle and daily growth bands on muscle apodemes. The methods can be used for finding the age of an insect in the teneral stage of the adult instar, in either laboratory or field material. Existing as well as potential applications are summarized with reference to teneral development and biochemistry; physiology and behaviour; and ecology (including pest ecology).     

A new reagent which may be used to introduce sulfhydryl groups into proteins, and its use in the preparation of conjugates for immunoassay

A synthesis of the N-hydroxysuccinimide ester of S-acetylthioacetic acid is described. This material is stable when stored dry and has advantages over the currently available reagents used to introduce sulfhydryl groups into a variety of proteins. Proteins modified with this reagent can be used to prepare conjugates for enzyme immunoassay. The conjugation techniques described cause little or no loss of either enzyme activity or antibody titer and function, and the conjugates contain little polymeric material.     

老年色素类荧光物质形成的生化机理

老年色素类荧光物质是人体基本生命过程中多种生化副反应的终产物,其中主要有与脂过氧化相关的通过不饱和羰基化合物与蛋白质交职而形成的荧光物质;有通过糖基化／美拉德反应而形成的糖基化终产物;有多聚烯起源的蓄存在视网膜色素上皮中的老年色素,另外,许多α-β-不饱和醛酮与核苷酸反应也能形成老年色素类生化聚合物,通过对老年色素形成的生化过程的研究发现,羰氨反应导致生物大分子的交联进而形成老年色素的过程是生物体内极为重要的与老化丰关的生物毒化过程。