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Extracellular masses of crystals are present in the endosternite of certain opilions (Phalangium, Odiellus, and Leiobunum). X-ray spectrography and secondary-ion analysis have shown them to be rich in calcium but poor in phosphorus and other elements. The associated anion has not been identified, but is most probably organic in nature and perhaps an oxalate.
Analyses of the chief volatile constituents of the defensive secretions of three oplionids were carried out. Leiobunum nigripalpi produces three closely related C7 compounds: E-4-methyl-4-hexen-3-one(I), 4-methylhexan-3-one(II), and 4-methylhexan-3-ol(III), along with E-4-methyl-4-hepten-3-one(IV), E,E-2,4-dimethylhexa-2,4-dienal(IX), and a minor, unidentified component. L. leiopenis secretion contains E-4-methyl-4-hepten-3-one(IV), 4-methylheptan-3-one(V), E,E-2,4-dimethylhexa-2,4-dien-1-ol(VII), and E,E-2,4-dimethylhepta-2,4-dien-1-ol(VIII). L. calcar yields chiefly E-4,6-dimethyl-6-octen-3-one(VI) and E,E-2,4-dimethylhexa-2,4-dien-1-ol(VII). Six of these compounds are new natural products. The structures of these compounds, which can be regarded either as polyketide-derived or as modified isoprenoids, raise interesting biosynthetic questions.
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The central nervous systems of web-building spiders (Araneidae, Agelenidae) and hunting spiders (Lycosidae, Salticidae) were tested for non-specific and specific phosphatases. Acid phosphatase exhibited weakly to moderately positive reactions in the neuronal cell bodies and in the neuropile fibre mass of all species investigated. Alkaline phosphatase could only be demonstrated in the external and internal neural lamellae of the brain and ventral cord of several specimens of the araneid species investigated. Tests for thiamine pyrophosphatase were negative with both the lead and calcium-cobalt methods. Distinctive positive reactions for adenosine triphosphatase were visible in the nervous system of all the species used, being especially strong in the optic ganglia of the hunting spiders. The demonstration of adenosine triphosphatase was only possible when applying the calcium-cobalt method after Padykula and Herman, while the lead method after Wachstein and Meisel did not produce any staining reaction at all. Controls of the histochemical reaction showed that the enzyme was activated by Ca2+ and inhibited by sulphydryl destroying reagents (e.g. PCMB), but was insensitive to ouabain. It could be probably classified as a mitochondrial proton-translocating adenosine triphosphatase.
The distribution and activity patterns of acetylcholinesterase in the central nervous system of araneid and agelenid spiders have been studied. Enzyme activity was limited to the neuropile mass. The araneid and agelenid species investigated exhibited largely similar acetylcholinesterase activity in different parts of the nervous system. Enzyme reactions were relatively less intense in the optic ganglia; the central body showed only weak to moderate reaction stainings.
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A first case of genuine neoplasm is reported in the order Araneida. This epithelial tumor, proceeding from oviduct ends, invades uterus; malignancy is strongly supported by cell structure and extensive local behavior.
Recent advances in higher-level invertebrate phylogeny have leveraged shared features of genomic architecture to resolve contentious nodes across the tree of life. Yet, the interordinal relationships within Chelicerata have remained recalcitrant given competing topologies in recent molecular analyses. As such, relationships between topologically unstable orders remain supported primarily by morphological cladistic analyses. Solifugae, one such unstable chelicerate order, has long been thought to be the sister group of Pseudoscorpiones, forming the clade Haplocnemata, on the basis of eight putative morphological synapomorphies. The discovery, however, of a shared whole genome duplication placing Pseudoscorpiones in Arachnopulmonata provides the opportunity for a simple litmus test evaluating the validity of Haplocnemata. Here, we present the first developmental transcriptome of a solifuge (Titanopuga salinarum) and survey copy numbers of the homeobox genes for evidence of systemic duplication. We find that over 70% of the identified homeobox genes in T. salinarum are retained in a single copy, while representatives of the arachnopulmonates retain orthologs of those genes as two or more copies. Our results refute the placement of Solifugae in Haplocnemata. Subsequent reevaluation of putative interordinal morphological synapomorphies among chelicerates reveals a high incidence of homoplasy, reversals, and inaccurate coding within Haplocnemata and other small clades, as well as Arachnida more broadly, suggesting existing morphological character matrices are insufficient to resolve chelicerate phylogeny.
We present a genome assembly from a male Linyphia triangularis (Common Sheetweb Spider Arthropoda; Arachnida; Araneae; Linyphiidae). The genome sequence has a total length of 1,349.10 megabases. Most of the assembly (95.36%) is scaffolded into 13 chromosomal pseudomolecules, including the X 1 and X 2 sex chromosomes. The mitochondrial genome has also been assembled and is 15.31 kilobases in length.
Granules were isolated from the cytoplasm of the amebocytes of Limulus polyphemus, the horseshoe crab, by disruption of cells obtained from blood which had been drawn into 2 mM propranolol. The granules subsequently were purified by centrifugation through a sucrose gradient that contained heparin. Extracts of the granules were prepared by freezing and thawing the granule preparations in distilled water. Transmission and scanning electron microscopy of the granules revealed round or ovoid particles. However, only one type of granule appeared to be present. The ultraviolet spectrum of the extract of amebocyte granules demonstrated a peak at 277 nm at pH 7.4, and a shift into two peaks of 281 nm and 290 nm at alkaline pH. Analytical ultracentrifugation revealed a pattern similar to that observed with lysates prepared from intact amebocytes. Polyacrylamide gel electrophoresis, in the presence of urea at pH 4.5, demonstrated patterns similar to those observed with amebocyte lysate. Extracts of the granules were gelled by bacterial endotoxin. The blood of the horseshoe crab contains only one type of cell, the amebocyte. Previous studies have shown that the blood coagulation mechanism of Limulus is contained entirely within amebocytes. The current studies suggest that the granules, which pack the cytoplasm of these cells, contain all of the factors required for the coagulation of blood, including the clottable protein. The intracellularly localized coagulation system is released from amebocytes when their granules rupture during cell aggregation.
Visual photoreceptors from both vertebrates and invertebrates are characterized by extensive elaboration of membrane which contains visual pigment (rhodopsin). Visual pigments in all phyla examined are chemically similar: the chromophore is 11-cis retinaldehyde attached by an aldimine linkage (Schiff base) to a membrane protein, opsin. The effect of light is to isomerize the chromophore to the all-trans configuration. Beyond these fundamental similarities, several specific areas are discussed in which variations and differences appear. (1) Light causes vertebrate visual pigments to bleach, liberating the chromophore. Most invertebrate visual pigments do not bleach in the light, but instead form a thermally stable metarhodopsin, with the chromophore in the all-trans configuration still attached to the opsin. (2) In the disk membranes of vertebrate rod and cone outer segments, the rhodopsin molecules are oriented with their chromophores nearly coplanar with the disks. Within this plane, however, both rotational and translational diffusion are possible. In the microvillar membranes of arthropod and cephalopod rhabdoms, on the other hand, the situation is less clear. There is evidence for some preferential orientation of chromophores that implies restrictions on Brownian rotation. (3) In the outer segments of vertebrate receptors, absorption of light by rhodopsin causes the plasma membrane to hyperpolarize due to a decrease in sodium conductance, possibly mediated by calcium ions. In most invertebrate photoreceptors, light causes a depolarization due to an increase in conductance, principally to sodium ions. A subsequent entry of calcium causes a partial repolarization of the membrane, due to a decrease in sodium conductance. (4) For vertebrate receptors, log threshold is directly proportional to the fraction of rhodopsin bleached (Dowling-Rushton relationship). The proportionality constant varies in different preparations from less than four to more than 30, and the physical basis for the relationship is unknown. For invertebrates, by contrast, the dependence of sensitivity on rhodopsin concentration is much less dramatic and may well depend simply on the probability of quantum catch. (5) In most species, vertebrate and invertebrate, the accumulation of photoproduct probably has no effect on membrane conductance, but several possible exceptions exist. (6) Photoregeneration of rhodopsin from metarhodopsin is likely an important mechanism of recovery in certain arthropods such as diurnal insects, but dark mechanisms of recovery also exist in all phyla. In no single case are they adequately understood.
Observations of a number of vertebrate chromatophores have revealed the presence of more than one type of pigment organelles, suggesting that the different types are all derived from an equipotential organelle able to differentiate into any of the major pigment-containing organelles (Bagnara, 1972). Observations are presented concerning the occurrence of hybrid pigment inclusions, i.e., all kinds of intergrades between melanosomes, pterinosomes, and reflecting platelets in pigment cells of the daddy-long-legs. It therefore seems possible that pigment organelles in some invertebrates may also be derived from a common pluripotential primordial organelle.
After treatment of spermatozoa of Phryne cincta from a Berlin population (bs) with low crossing-over and from an Alpine population (as) with high crossing-over frequency, egg mortality was ascertained and chromosomal mutation rate determined by examination of the polytene chromosomes of the F1 progeny. - The as stock exhibits a 1.33 times greater radiation sensitivity than the bs stock, both in chromosomal mutation and in egg mortality rates. There is no evidence that factors other than structural ones account for the differences in radiation sensitivity. From inversion length measurements, it was proposed that a reduction of the spiral diameter of the paternal pronucleus chromosomes is responsible for a higher site number and thereby for a greater radiation sensitivity.
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