An Unexpected Diversity of Photoreceptor Classes in the Longfin Squid,Doryteuthis pealeii

Cephalopods are famous for their ability to change color and pattern rapidly for signaling and camouflage. They have keen eyes and remarkable vision, made possible by photoreceptors in their retinas. External to the eyes, photoreceptors also exist in parolfactory vesicles and some light organs, where they function using a rhodopsin protein that is identical to that expressed in the retina. Furthermore, dermal chromatophore organs contain rhodopsin and other components of phototransduction (including retinochrome, a photoisomerase first found in the retina), suggesting that they are photoreceptive. In this study, we used a modified whole-mount immunohistochemical technique to explore rhodopsin and retinochrome expression in a number of tissues and organs in the longfin squid, Doryteuthis pealeii. We found that fin central muscles, hair cells (epithelial primary sensory neurons), arm axial ganglia, and sucker peduncle nerves all express rhodopsin and retinochrome proteins. Our findings indicate that these animals possess an unexpected diversity of extraocular photoreceptors and suggest that extraocular photoreception using visual opsins and visual phototransduction machinery is far more widespread throughout cephalopod tissues than previously recognized.     

Isolation and PCR detection of <Emphasis Type="Italic">Enterobacter sakazakii</Emphasis> in South African food products,specifically infant formula milks

Enterobacter sakazakii has recently been identified as an opportunistic pathogen. The current culture-dependent detection methods for these bacteria are time-consuming and in this study a PCR method for the detection of E. sakazakii in South African food products, including an internal amplification control (IAC) was developed. DNA was isolated and amplified from the products and they were plated on selective growth media after pre-enrichment and enrichment in Enterobacteriaceae enrichment broth. Four of the 22 products tested positive for the presence of E. sakazakii, confirmed by PCR detection and growth on selective media. The PCR method proved effective in detecting E. sakazakii in South African products after three days and could serve as an alternative for traditional microbiological techniques.     

Characterization of Disease-related 5β-Reductase (AKR1D1) Mutations Reveals Their Potential to Cause Bile Acid Deficiency

Bile acid deficiency is a serious syndrome in newborns that can result in death if untreated. 5β-Reductase deficiency is one form of bile acid deficiency and is characterized by dramatically decreased levels of physiologically active 5β-reduced bile acids. AKR1D1 (aldo-keto reductase 1D1) is the only known human enzyme that stereo-specifically reduces the Δ⁴ double bond in 3-keto steroids and sterols to yield the 5β-hydrogenated product. Analysis of the AKR1D1 gene in five patients with 5β-reductase deficiency revealed five different mutations resulting in an amino acid substitution in the protein. To investigate a causal role for these observed point mutations in AKR1D1 in 5β-reductase deficiency, we characterized their effect on enzymatic properties. Attempts to purify mutant enzymes by overexpression in Escherichia coli only yielded sufficient amounts of the P133R mutant for further characterization. This enzyme displayed a highly reduced K_m and V_max reminiscent of uncompetitive kinetics with 4-cholesten-7α-ol-3-one as substrate. In addition, this mutant displayed no change in cofactor affinity but was more thermolabile in the absence of NADPH as judged by CD spectroscopy. All mutants were compared following expression in HEK 293 cells. Although these enzymes were equally expressed based on mRNA levels, protein expression and functional activity were dramatically reduced. Cycloheximide treatment also revealed that several of the expressed mutants were less stable. Our findings show that the reported mutations in AKR1D1 in patients with 5β-reductase lead to significantly decreased levels of active enzyme and could be causal in the development of bile acid deficiency syndrome.     

Identification of Bacilysin, Chlorotetaine, and Iturin A Produced by Bacillus sp. Strain CS93 Isolated from Pozol, a Mexican Fermented Maize Dough

Three antimicrobial compounds produced by Bacillus sp. strain CS93 isolated from pozol were identified by using high-performance liquid chromatography and mass spectrometry. The three compounds were iturin, bacilysin, and chlorotetaine. Production of these compounds by CS93 could account for the medicinal properties attributed to pozol.     

Lipid and pigment changes during shoot initiation in cultured explants of Pinus radiata

Cotyledon explants of radiata pine contain principally lipid and protein reserve materials, which decline during shoot initiation. This process was followed phytochemically and ultrastructurally. Fatty acid and sterol analyses indicated that there were both quantitative and qualitative changes in the different classes of lipid. The most pronounced changes were an increase in the linolenic acid content of the polar lipids and the appearance of stigmasterol during shoot initiation. There was also a continued increase in chlorophyll and carotenoid levels, which paralleled chloroplast development. It appears that the changes observed were similar to those that occur in cotyledons during normal seedling development.     

The aggressive behaviour of individual male polecats (Mustela putorius, M. furo and hybrids) towards familiar and unfamiliar opponents

Experiments are described which were designed to investigate the significance of individual differences in aggressiveness between polecats and the relation between the familiarity of the opponent and the pattern and outcome of fighting.
The behaviour of Mustela putorius, M. furo and hybrids between the two species was investigated in an indoor arena of 16 m².
Two kinds of fighting between male polecats were recorded, "companion fighting" between cage mates, in which biting was inhibited and neither of the opponents became intimidated and "uninhibited fighting" between unfamiliar individuals from which a winner and loser generally emerged and a rank order formed.
Individual differences in aggressiveness were assessed by means of a scoring system which statistical analysis showed, generally, to be consistent for any one individual. The rank of an animal, however, was found not to be invariably related to its aggression score.
A number of other factors influencing fighting were investigated, the earlier introduction of one individual into the arena increases its chances of winning a fight; when offered a choice, male polecats fight strangers in preference to cage mates; and the separation of a group of cage mates for as little as 48 hours induces them to behave towards one another like strangers with the result that a rank order is formed. Factors which had no apparent effect on fighting between males were the weight of the individual or the presence of females.
The attributes of familiar and unfamiliar opponents are discussed in the light of these findings.