Chlorophyll Composition in an Isolated Chlorophyll a-Protein Complex of Photosystem I

A P700-chlorophyll a-protein complex, solubilized by the detergent Triton X-100, has been isolated by hydroxyl apatite column chromatography. The chlorophyll composition was determined by thin-layer chromatography and spectrofluorimetric analysis. This photosystem I reaction centre complex, prepared at pH 7, contained pheophytin a and P700 in a ratio of 2/1, high enough to account for a composition similar to that in the reaction centre of photosynthetic bacteria. Prepared at pH 9, the same ratio was 0.2/1, which excludes pheophytin a from having the same function as that of bacterio-pheophytin in the photosynthetic bacteria.     

Beyond the wasp‐waist: structural diversity and phylogenetic significance of the mesosoma in apocritan wasps (Insecta: Hymenoptera)

A comprehensive data set of hymenopteran mesosomal anatomy is presented and analysed. Eighty‐nine taxa, including three outgroups, were scored for 273 characters. Analyses were carried out under different weighting conditions (equal and implied weights). Topologies retrieved for the non‐apocritan Hymenoptera were highly congruent with previously published results. Apocrita were always retrieved as monophyletic, as were most superfamilies. Relationships amongst apocritan superfamilies were mostly weakly corroborated. Stephanoidea were almost always the sister group to the remaining Apocrita. Evaniomorpha were usually retrieved, Ceraphronoidea being the sister group to Megalyroidea, and Evanioidea to Trigonaloidea. Aculeata did not always come out as monophyletic, and of the aculeate superfamilies, only Apoidea was retrieved. Ichneumonoidea were always monophyletic and often the sister group of Aculeata. Maamingidae and Mymarommatoidea were usually sister groups; together, they often form the sister group of Chalcidoidea. A large clade comprising Cynipoidea, Platygastroidea, and Proctotrupoidea was usually retrieved, the two former superfamilies being nested within Proctotrupoidea. Cynipoidea were usually closely related to some of the Diapriidae. Platygastroidea were usually the sister group of a clade comprising Heloridae, Pelecinidae, Proctotrupidae, and Vanhorniidae. The mesosomal region proved to be a very substantial source of phylogenetically relevant information. The results of the present analyses indicate that a reclassification, especially of Proctotrupoidea, is required, but this should be carried out after thorough analyses of more comprehensive combined data sets. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 22–194.     

Effects of concentrating phytoplankton on the acetylene-reduction assay for nitrogenase activity

SUMMARY.

• 1 The consequences of concentrating freshwater phytoplankton communities prior to measurement of nitrogenase activity using the acetylene-reduction assay were investigated.
• 2 Retention of heterocystous blue-green algae by 10 and 45 öm plankton nets was usually much less than 100% and the percent retention differed among blue-green algal species and varied for the same species both on different sampling dates and in different lakes. Retention of heterocyst numbers and helerocyst volume during concentration differed from that of total cell volume of heterocystous blue-green algae.
• 3 Effects of concentration on specific nitrogcnase activity varied among the lakes studied. In Lake Bysjön activity decreased on all sampling occasions, in Lake Trummen there was no apparent effect, and in Lake Vaxjosjon both results were found.
• 4 Effects on nitrogenase activity of mechanical disturbance during concentration and of increased pH. reduced carbon availability. light inhibition and subsaturation. photorespiration and oxygen supersaturation in concentrated samples are discussed. Interactions between these factors are suggested to explain the varying responses in the three lakes.
• 5 It is concluded that phytoplankton should not be concentrated in the acetylene-reduction assay for nitrogenase activity, since both volumetric and cell concentration factors are inadequate and effects of concentration on specific nitrogenase activity are not predictable.

     

Spawning coloration and sperm quality in a large lake population of Arctic charr (Salmonidae: Salvelinus alpinus L.)

The modern theories of sexual selection predict that male sexual ornaments may have evolved as reliable signals of male fertilization efficiency. However, among the studies of fishes with external fertilization, the results have yielded ambiguous evidence. In the present study, we present data on the phenotypic relationships between red spawning coloration and ejaculate quality (spermatocrit, sperm motility) from Arctic charr, Salvelinus alpinus. We studied two generations (F₁ and F₂) of males from a large lake population, reared in a standardized hatchery environment, to determine whether differential hatchery history, or duration of hatchery selection, affected the variation in ejaculate characteristics or abdominal coloration. After controlling for body length, there was no difference between the hatchery generations in these traits. However, the degree of redness increased with fish size. We found a positive correlation between sperm velocity and sperm longevity, indicating a functional integration between these sperm features across generations. Sperm velocity was also positively correlated with male redness. Therefore, the finding obtained in the present study suggests that the carotenoid‐based ornamentation in Arctic charr may provide information about differences between males in their fertilization potential. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 794–802.     

Earliest ontogeny of Early Palaeozoic Craniiformea: implications for brachiopod phylogeny

Popov, L.E., Bassett, M.G., Holmer, L.E., Skovsted, C.B. & Zuykov, M.A. 2010: Earliest ontogeny of Early Palaeozoic Craniiformea: implications for brachiopod phylogeny. Lethaia, Vol. 43, pp. 323–333. Well preserved specimens of the Early Palaeozoic craniiform brachiopods Orthisocrania and Craniops retain clear evidence of a lecithotrophic larval stage, indicating the loss of planktotrophy early in their phylogeny. The size of the earliest mineralized dorsal shell was <100 μm across, and the well preserved shell structure in these fossil craniiforms allows their earliest ontogeny to be compared directly with that of living Novocrania, in which the first mineralized dorsal shell (metamorphic shell) is secreted only after settlement of the lecithotrophic larvae. Immediately outside this earliest shell (early post‐metamorphic or brephic shell) and in the rest of the dorsal valve the primary layer in both fossil and living craniiforms has characteristic radially arranged laths, which are invariably lacking in the earliest dorsal shell. The ventral valve of the fossil specimens commonly preserves traces of an early attachment scar (cicatrix), which is equal in size to the dorsal metamorphic shell, and the brephic post‐metamorphic ventral valve also has a primary shell with radially arranged laths. However, a primary shell with radial laths is completely lacking in the ventral valve of living Novocrania, indicating that heterochrony may have been involved in the origin of the encrusting mode of life in living craniids; the entire ventral valve of Recent craniids (with the possible exception of Neoancistrocrania) may correspond to the earliest attachment scar of some fossil taxa such as Orthisocrania. It is also probable that the unique absence of an inner mantle lobe as well as the absence of lobate cells in Novocrania could be the result of heterochronic changes. The dorsal valve of both fossil and living craniiforms has a marked outer growth ring, around 500 μm across, marking the transition to the adult, and a significant change in regime of shell secretion. The earliest craniiform attachment is considered to be homologous to the unique attachment structures described recently in polytoechioids (e.g. Antigonambonites) and other members of the strophomenate clade. However, unlike the craniiforms, polytoechioids and strophomenates all have planktotrophic larvae, and planktotrophy is most probably a plesiomorphic character for all Brachiopoda. □Brachiopoda, Craniiformea, Early Palaeozoic, ontogeny, phylogeny.     

Micro‐climate determines oviposition site selection and abundance in the butterfly Pyrgus armoricanus at its northern range margin

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The influence of rate of temperature change and peak stimulus duration on pain intensity and quality

An important aspect of experimental pain research is that the assessment methods can investigate the different aspects of pain perception. The aim of the present study was to investigate the influence of rate of temperature change and peak stimulus duration on heat evoked pain intensity and quality. All stimuli were applied within the medial aspect of the anterior forearm. The rate of temperature change was varied from 1 to 16 C/s without any effect on the pain threshold. The pain threshold decreased with an increasing peak stimulus duration from 0.1 to 2 s, but not from 2 to 3 s. The pain intensity for suprathreshold stimuli (46 C, 48 C, 50 C) increased for decreasing rates and increasing duration. The pain intensity was highly correlated with the energy of the stimulus. When the rates of temperature change (1-16 C/s) are varied, no differences between pricking and burning pain were present at either low stimulus intensity (46 C) or high stimulus intensity (50 C). At low stimulus intensity (46 C), the pricking pain was not influenced by the duration (0.1-3 s), but the burning pain was intensified when the duration was increased from 1.5 to 3 s. At high intensity stimuli (50 C), the pricking pain intensified with an increased duration, whereas burning pain did not. The heat pain threshold is influenced by the peak stimulus duration, and not by the rate of temperature change. If suprathreshold stimuli are used, both the rate of temperature change and the peak stimulus duration can strongly affect the pain intensity and the pain quality. Therefore, the same stimulus modality can be used to assess the modulation of different pain intensities and of the pricking and burning pain qualities simply by varying the stimulus configuration.     

Allohyaena (Mammalia: Carnivora): giant hyaenid from the Late Miocene of Hungary

The topotypic material of the giant Late Miocene hyaenid Allohyaena kadici Kretzoi is described. New data on the deciduous dentition shows unambiguously that A. kadici is a hyaenid and not a percrocutid as reported by some previous authors. A. kadici is compared to the large hyaenids Adcrocuta eximia and Crocuta crocuta. These comparisons show that A. kadici has a mixture of primitive characters such as dp4 morphology, retention of m2, long and slender premolars and a large protocone on P4, and derived characters such as a preparastyle on P4, an internal root on P3 and a uniquely derived talonid structure of ml. This combination of features makes A. kadici difficult to classify, but it is considered to probably be most closely related to derived, bone-cracking hyaenids such as Pachycrocuta and Crocuta. A. kadici is rare in the fossil record, being found at only two sites. We suggest that the reason for this rarity is that it had a geographic and stratigraphic range which is poorly sampled in the Miocene fossil record of Europe.