Changes in the lipid composition of Paecilomyces persicinus P-10 M1 during growth and cephalosporin C production

The lipid composition of the fungus Paecilomyces persicinus P-10 M1 was monitored daily for 6 days to detect any changes during growth and cephalosporin C production. Total lipid yields and cephalosporin C production were maximal after 72 h of incubation. Analysis of the total lipids revealed that the neutral lipid fraction was elevated at this time, whereas polar lipids were depressed. Phosphatidylethanolamine and phosphatidylcholine represented the major phospholipids detected. Phosphatidylethanolamine levels were descending when cephalosporin C was detected at its highest concentration. Increases in phosphatidylcholine levels paralleled those of cephalosporin C but reached a maximum at 48 h after the latter. Diphosphatidylglycerol, phosphatidic acid, and phosphatidylserine were also detected. Fatty acids present in the total lipid fraction ranged in carbon length from C12 to C24. The major acids were C16 (palmitic), C18:1 (oleic), and C18:2 (linoleic). All fatty acids exhibited minor variations in concentration during the 6-day period, and none displayed a direct correlation with cephalosporin C yields.     

Relationship between the golgi apparatus, gerl, and secretory granules in acinar cells of the rat exorbital lacrimal gland

The method of secretory granuleformation in the acinar cells of the rat exorbital lacrimal gland was studied by electron microscope morphological and cytochemical techniques. Immature secretory granules at the inner face of the Golgi apparatus were frequently attached to a narrow cisternal structure similar to GERL as described in neurons by Novikoff et al. (Novikoff, P. M., A. B. Novikoff, N. Quintana, and J.-J. Hauw. 1971. J. Cell Bio. 50:859-886). In the lacrimal gland. GERL was located adjacent to the inner Golgi saccule, or separated from it by a variable distance. Portions of GERL were often closely paralleled by modified cisternae of rough endoplasmic reticulum (RER), which lacked ribosomes on the surface adjacent to GERL. Diaminobenzidine reaction product of the secretory enzyme peroxidase was localized in the cisternae of the nuclear envelope, RER, peripheral Golgi vesicles, Golgi saccules, and immature and mature secretory granules. GERL was usually free of peroxidase reaction product or contained only a small amount. Thiamine pyrophosphatase reaction product was present in two to four inner Golgi saccules; occasionally, the innermost saccule was dilated and fenestrated, and contained less reaction product than the next adjacent saccule. Acid phosphatase (AcPase) reaction product was present in GERL, immature granules, and, rarely, in the innermost saccule, but not in the rest of the Golgi saccules. Thick sections of AcPase preparations viewed at 100 kV revealed that GERL consisted of cisternal, and fenestrated or tublular portions. The immature granules were attached to GERL by multiple connections to the tublular portions. These results suggest that, in the rat exorbital lacrimal gland, the Golgi saccules participate in the transport of secretory proteins, and that GERL is involved in the formation of secretory granules.     

Benefits,costs and reactivity of inducible defences: an experimental test with rotifers

1. A key aspect of the ecology and evolution of adaptive prey responses to predator risk is the timing by which the former develop a defensive trait in response to inducing signals released by the latter. This property, called reactivity, has been shown to affect population stability and persistence. 2. Theoretically, the minimal predator density required by prey to exhibit induced defences is expected to increase with the effectiveness of the defence and decrease with its cost. Likewise, the time required for the prey population to exhibit an induced defence is expected to increase together with cost. 3. The freshwater rotifers Brachionus calyciflorus and B. havanaensis and their predator Asplanchna brightwelli were used to test the hypothesis that prey species exhibiting defences that offer a larger fitness benefit and lower fitness cost are more reactive to predator signals, in terms of requiring shorter exposure time and lower signal concentration to trigger a morphological defence reaction. 4. Our results showed that both prey species exhibited costly and effective defences after induction by predator infochemicals. Faster reactions were observed at higher levels of predator cues. Nevertheless, the observed relationship between reactivity and benefit/cost of defences did not agree with our expectations. 5. To our knowledge, this is the first study in which the timing of induction of morphological defences is experimentally assessed over a gradient of risk signals. We propose new research directions to disentangle the mechanisms and project the consequences of prey decisions at the morphological level.     

MicroRNA expression profiling of the developing murine upper lip

Clefts of the lip and palate are thought to be caused by genetic and environmental insults but the role of epigenetic mechanisms underlying this common birth defect are unknown. We analyzed the expression of over 600 microRNAs in the murine medial nasal and maxillary processes isolated on GD10.0–GD11.5 to identify those expressed during development of the upper lip and analyzed spatial expression of a subset. A total of 142 microRNAs were differentially expressed across gestation days 10.0–11.5 in the medial nasal processes, and 66 in the maxillary processes of the first branchial arch with 45 common to both. Of the microRNAs exhibiting the largest percent increase in both facial processes were five members of the Let‐7 family. Among those with the greatest decrease in expression from GD10.0 to GD11.5 were members of the microRNA‐302/367 family that have been implicated in cellular reprogramming. The distribution of expression of microRNA‐199a‐3p and Let‐7i was determined by in situ hybridization and revealed widespread expression in both medial nasal and maxillary facial process, while that for microRNA‐203 was much more limited. MicroRNAs are dynamically expressed in the tissues that form the upper lip and several were identified that target mRNAs known to be important for its development, including those that regulate the two main isoforms of p63 (microRNA‐203 and microRNA‐302/367 family). Integration of these data with corresponding proteomic datasets will lead to a greater appreciation of epigenetic regulation of lip development and provide a better understanding of potential causes of cleft lip.     

Developmental expression and activity of high affinity glutamate transporters in rat cortical primary cultures

The expression and activity of glutamate transporters (EAAC1, GLAST and GLT1) were examined during the development of cortical neuron-enriched cultures. Protein content and mitochondrial respiration both increased during the first 7 days, later stabilized and decreased from DIV14. Glutamate transport and extracellular concentration were relatively constant from DIV3 to 18. The kinetic parameters of glutamate transport were at DIV7:K_m=19±3 μM and V_max=1068±83 pmol/mg protein/min and at DIV14: K_m=40.8±9.3 μM and V_max=1060±235 pmol/mg protein/min. The shift in K_m towards higher values suggest a more important participation of GLAST after DIV14. At DIV7 and 14, glutamate transport was poorly sensitive to dihydrokaïnate (DHK) suggesting a weak participation of GLT1 in glutamate transport. Western blot experiments and immunocytochemistry showed that EAAC1 was expressed by neurons whatever the stage of the culture. GLAST was found in astrocytes as soon as DIV3 and labeling increased during the development of the culture. There was little neuronal GLT1 immunoreactivity at DIV7, only detected by immunocytochemistry. From DIV10 to 18, an increasing astrocytic expression of GLT1 was observed, also detected by Western blotting. These results show that: (1) glutamate uptake remains stable all along the development of the cultures although the pattern of expression of the different transporters is changing, suggesting that glutamate transport is highly regulated; (2) neuronal EAAC1 may play a critical role during the early stages of the culture when it is expressed alone; and (3) the developmental expression pattern of glutamate transporters in cortical neuron-enriched cultures is quite similar to that observed in vivo during early postnatal development.     

Phylogenetic relationships and taxonomic position of Chlorella -like isolates from low pH environments (pH < 3.0)

Background  

Little is known about phytoplankton communities inhabiting low pH environments such as volcanic and geothermal sites or acidic waters. Only specialised organisms are able to tolerate such extreme conditions. There is, thus, low species diversity. We have characterised the previously isolated acid tolerant Chlorella -like microalgae Viridiella fridericiana and Chlorella protothecoides var. acidicola by microscopical and biomolecular methods in order to assess their phylogenetic relationships.