Use of plasmid pULB113 (RP4::Mini-Mu) to construct a genomic map ofAeromonas hydrophila

Plasmid pULB113 (RP4::Mini-Mu) promoted homologous gene transfer inAeromonas hydrophila; transfer of chromosomal markers occurred at frequencies of between 10^–3 and 10^–4 per donor cell regardless of the marker selected; this indicated chromosome transfer from multiple origins. With a variety of amino acid biosynthetic markers, a single circular map of this bacterium was constructed.     

Proteomic identification of interactions between histones and plasma proteins: Implications for cytoprotection

Extracellular histones released from cells during acute inflammation contribute to organ failure and death in a mouse model of sepsis, and histones are known to exert in vitro cytotoxicity in the absence of serum. Since addition of histones to serum and plasma is known to induce protein aggregation, we reasoned that plasma proteins may afford protection from cytotoxicity. We found that MODE‐K mouse small intestinal epithelial cells were protected from histone‐induced toxicity in the presence of 10% FCS. Therefore, the main aim of this study was to identify histone‐interacting plasma proteins that might be involved in cytoprotection. The precipitate formed following addition of calf thymus histones to human EDTA plasma was characterised by shotgun proteomics, identifying a total of 36 protein subunits, including complement components, coagulation factors, protease inhibitors and apolipoproteins. The highly sulphated glycosaminoglycan heparin inhibited histone‐induced plasma protein aggregation. Moreover, histones bound to heparin agarose were capable of pulling down plasma proteins from solution, indicating their effective cross‐linking properties. It was particularly notable that inter‐α‐trypsin inhibitor was prominent among the histone‐precipitated proteins, since it contains a chondroitin sulphate glycan chain, and suggests a potential role for this protein in histone sequestration during acute inflammation in vivo.     

Genetic screening for prey in the gut contents from a giant squid (Architeuthis sp.)

Giant squids (Architeuthis sp.) remain mysterious; they have evaded observation and are rarely taken from their deep sea habitat. Information on the diet of Architeuthis is scarce due to the limited number of specimens with morphologically recognizable remains in their digestive tracts. We explored the use of polymerase chain reaction (PCR)-based methods for detection of DNA in the prey remains and amorphous slurry from an Architeuthis gut sample. The DNA region amplified varied in size, allowing separation of fish and squid components. Sequence comparisons identified fish prey as Macruronus novaezelandiae. Isolation of Architeuthis DNA from an ingested tentacle and the presence of chitin fragments indicate cannibalism occurs in giant squid. Denaturing gradient gel electrophoresis was used to screen for less common DNA types, revealing a high frequency of PCR-generated false alleles, but no additional prey species.     

The third way: spermcast mating in sessile marine invertebrates

Marine invertebrates belonging to a broad range of taxa disperseaquatic spermatozoa to fertilize eggs that are retained ratherthan spawned. We outline the occurrence of this mechanism, whichwe refer to as spermcast mating, and identify tentative generalizationsrelating to it. Contrasts are drawn where appropriate with broadcastspawning of both eggs and sperm for external fertilization,and with copulation or pseudocopulation. Spermcast mating mayinvolve the gradual accumulation of long-lived spermatozoa fromdilute suspension, probably during suspension feeding, and thesubsequent storage of spermatozoa by the recipient (acting female)prior to fertilization. This process may involve extensive contactbetween spermatozoa and recipient (maternal) tissue. Matingmay be influenced by compatibility systems, and receipt of compatibleallosperm may trigger female investment, giving apparent scopefor sexual conflict over levels of maternal investment. Externalfertilization of cohesive egg masses remaining close to theacting female may appear somewhat intermediate between spermcastmating and broadcast spawning but, while it may be possibleto envisage a continuum between the 2 modes, the end pointsare distinct, commonplace, and involve contrasting reproductivecharacteristics. Three variants of the typical pattern of spermcastmating are briefly discussed: the spawning of zygotes (ratherthan the more usual brooding of progeny), polyembryony, andthe dispersal of spermatophores rather than individual spermatozoa.