Defensive secretions of larvae of a carabid beetle

Secretions of an eversible gland on the metathorax of larvae of Chlaenius cordicollis Kirby (Coleoptera: Carabidae) are investigated by headspace analysis using solid phase microextraction followed by gas chromatography‐mass spectrometry (GC‐MS). Larvae from Manitoba, Canada and Pennsylvania, U.S.A., are sampled. Nine presumed defensive compounds are detected when the gland is everted, and this represents the first characterization of defensive secretions of larvae of a carabid beetle. With the exception of a single component (2‐methoxy‐4‐methylphenol), these compounds are distinct from those found in the defensive secretion of adult C. cordicollis. However, seven are more oxidized versions of the alkylphenolic compounds secreted by adult beetles: three hydroquinones (hydroquinone, methylhydroquinone and 2,3‐dimethylhydroquinone) and four quinones (p‐benzoquinone, toluquinone, 2,3‐dimethylquinone and ethyl‐p‐benzoquinone). An additional alkoxyphenol (2‐methoxy‐4‐ethylphenol) is also detected. Two patterns of composition are observed: in one, p‐benzoquinone and hydroquinone are undetectable and the ratio of toluquinone : 2,3‐dimethylquinone is 1 : 4.6 ± 0.6 (mean ± SE); in the other, all nine compounds are detectable and the ratio of toluquinone : 2,3‐dimethylquinone is 1 : 1.0 ± 0.2. These differences in pattern do not appear to be related to geographical source, sex or age of the larvae.     

Presence of haemocyte-like cells in coccinellid reflex blood

Abstract.  Contrary to current assumptions, the reflex blood of two-spot ladybirds, Adalia bipunctata , and seven-spot ladybirds, Coccinella septempunctata , contains haemocyte-like cells. Furthermore, DNA can be extracted and amplified from coccinellid reflex blood, confirming the presence of haemocyte-like cells and demonstrating a nondestructive method of DNA extraction.     

Synthesis of a "free" form of hyaluronic acid by articular chondrocytes in monolayer culture

Primary and first passage rabbit chondrocyte cultures synthesized a "free" form of hyaluronic acid (HA-f) previously characterized in rabbit cartilage. HA-f was isolated from the [3H] glcN/35SO4-labelled cell-associated-fraction (CAF) and from the culture medium by successive equilibrium centrifugations in Cs2SO4/CsCl/Cs2SO4 under low salt conditions. The culture medium HA-f appeared in the void volume of Sepharose CL-2B eluted with low salt, (0.5M sodium acetate), and was susceptible to digestion with Streptomyces hyaluronidase. HA-f aggregated purified rabbit cartilage proteoglycan monomer. These results indicated that HA-f probably subserves hyaluronic acid already complexed with proteoglycan monomer. Newly synthesized HA-f may be required for the continual formation of proteoglycan aggregates.     

Phaseollin production in cell suspensions and whole plants of Phaseolus vulgaris

Production of phaseollin was measured in cell suspension cultures and whole plants of Phaseolus vulgaris. In suspension cultures phaseollin appeared when there was no further increase in cell mass. Cells transferred to a medium without auxins yielded three times higher phaseollin concentrations than cells grown in their presence. Addition of autoclaved fungal mycelia or polysaccharides as elicitors resulted in an increased phaseollin concentration in the cell suspension.In whole plants phaseollin could be detected only after the plants were challenged by a fungus which caused lesions (browning) of the upper root neck region, Rhizoctonia solani. Treatment of non-infected plants with autoclaved fungal mycelia or other elicitors did not induce phaseollin production. However, when they were added before or together with the pathogenic fungus, the elicitors further increased phaseollin concentration in the root neck regions of the plants. This indicated that the pathogenic fungus was important for the penetration of the elicitors to inner plant tissues where phaseollin (and probably other phytoalexins) is produced.     

Locus determining the human sperm-specific lactate dehydrogenase, LDHC, is syntenic with LDHA

From the data presented in this report, the human LDHC gene locus is assigned to chromosome 11. Three genes determine lactate dehydrogenase (LDH) in man. LDHA and LDHB are expressed in most somatic tissues, while expression of LDHC is confined to the germinal epithelium of the testes. A human LDHC cDNA clone was used as a probe to analyze genomic DNA from rodent/human somatic cell hybrids. The pattern of bands with LDHC hybridization is easily distinguished from the pattern detected by LDHA hybridization, and the LDHC probe is specific for testis mRNA. The structural gene LDHA has been previously assigned to human chromosome 11, while LDHB maps to chromosome 12. Studies of pigeon LDH have shown tight linkage between LDHB and LDHC leading to the expectation that these genes would be syntenic in man. However, the data presented in this paper show conclusively that LDHC is syntenic with LDHA on human chromosome 11. The terminology for LDH genes LDHA, LDHB, and LDHC is equivalent to Ldh1, Ldh2, and Ldh3, respectively.     

Differential growth of the branches of a regenerating bifurcate axon is associated with differential axonal transport of organelles

Axonal trees display differential growth during development or regeneration; that is, some branches stop growing and often retract while other branches continue to grow and form stable synaptic connections. In this study, an in vitro model of differential growth is examined to identify the intracellular events responsible for this phenomenon. When the giant cerebral neuron of Aplysia californica is placed in culture, vigorous growth occurs from the ends of both branches of its bifurcate axon. If an appropriate target neuron is placed next to one branch, growth from that branch is unabated while growth from the other branch is suppressed. The bidirectional fast transport of membranous organelles was examined in the two branches by the use of high-resolution video microscopy. Transport was similar in the branches in the absence of a target cell but was much greater in the growing than in the nongrowing branch when a target was present. Electron microscopic examination of fixed specimens confirmed these findings. Differential growth may be initiated or sustained by a diversion from certain branches of materials used in growth which are supplied by fast axonal transport.     

The energy utilized in protein breakdown by the ATP-dependent protease (La) from Escherichia coli

A crucial enzyme in the pathway for protein degradation in Escherichia coli is protease La, an ATP-hydrolyzing protease encoded by the lon gene. This enzyme degrades various proteins to small polypeptides containing 10-20 amino acid residues. To learn more about its energy requirement, we determined the number of ATP molecules hydrolyzed by the purified protease for each peptide bond cleaved. The enzyme hydrolyzed about 2 molecules of ATP for each new amino group generated with casein, bovine serum albumin, glucagon, or guanidinated casein as substrates, even though these proteins differ up to 20-fold in size and 3-4 fold in rates of hydrolysis of peptide bonds. Similar values for the stoichiometry (from 1.9 to 2.4) were obtained using fluorescamine or 2,4,6-trinitrobenzene sulfonic acid to estimate the appearance of new amino groups. These values appeared lower at 1 mM than at 10 mM Mg2+. The coupling between ATP and peptide bond hydrolysis appeared very tight. However, when the protease was assayed under suboptimal conditions (e.g. at lower pH or with ADP present), many more ATP molecules (from 3.5 to 12) were consumed per peptide bond cleaved. Our data would indicate that the early steps in protein degradation consume almost as much energy (2 ATPs for each cleavage) as does the formation of peptide bonds during protein synthesis.