Observations on temperature optimum,cyst production,and survival of Streptocephalus proboscideus (Frauenfeld, 1873) (Crustacea: Anostraca), fed different diets

Somatic growth in S. proboscideus, fed Chlorella vulgaris increased with temperature reaching a plateau after about 8 to 11 days at between 26 and 31 °C. Survival was best below 29 °C. Fertility (the number of cysts produced per female) and survival, tested at 27 °C, demonstrated some variability as a function of the composition of four different diets. However, large variances and few replicates make exact evaluation impossible.It was found that S. proboscideus can successfully be cultured, using a variety of food sources. Only pure Spirulina platensis gave unsatisfactory results in terms of low cyst production and high mortality. Filamentous blue-green algae, because of their possible toxicity, should preferably be excluded from formulated diets.     

Influence of light,DMSO and glycerol on the hatchability ofThamnocephalus platyurus Packard cysts

Effects of two light intensities and different concentration of dimethyl sulfoxide (DMSO) and glycerol on hydrated cyst hatching inThamnocephalus platyurus were studied. A maximum of 65±6% hatching was recorded within seven days at 2500 lux continuous light regime. Hatching was at a minimum during the first two days, peaked between the third and fourth days, decreased thereafter. Hatching success was a function of duration of light exposure. Eight percent of cysts hatched in the dark, while cysts exposed to 24h light and subsequently incubated in the dark showed 27±2% hatching. Hatchability was significantly increased (23%) in 0.0375% DMSO and 0.0125% glycerol. Concentration above 0.05% DMSO and 0.025% glycerol had no or a negative influence on hatching. Since low concentrations of DMSO were non-toxic, apolar compounds like Ca²⁺ ionophore can be dissolved in DMSO to study the role of Calcium in cyst hatching.     

In situ hatching of Artemia monica cysts in hypersaline Mono Lake,California

Two emergence trap designs were tested in Mono Lake, California, to measure in situ hatching of Artemia monica cysts on the lake bottom. One design incorporated a removable sample bottle; the other had a catch tube which was pumped from the surface. Both traps rested on the bottom and had a narrow gap between the collecting funnel and bottom flange to allow the chemical conditions within the trap to be similar to those outside. This gap was open during April and May but, because some animals entered from outside the area enclosed by the trap, the gap was covered with 400 µm or 800 µm screen during June and July. The two trap types without screens sampled a station in oxic water 7 m deep similarly in April and May 1985. Mean daily hatching rates from April to May 1985 ranged from 720 to 25 340 shrimp m^-2 day^-1. In contrast, mean daily hatching rates during the same period at a station in anoxic water 21 m deep were from 3 to 138 shrimp m^-2 day^-1. June and July hatching rates in the shallow station were lower than in the spring, usually less than 1000 shrimp m^-2 day^-1.     

Human epidermis reconstructed in vitro: A model to study keratinocyte differentiation and its modulation by retinoic acid

Summary It was possible to reconstruct epidermis in vitro by seeding dissociated keratinocytes on de-epidermized dermis and growing such recombined cultures for 1 wk, exposed to air, at the surface of the culture medium. These conditions were chosen to mimic the transdermal feeding and the exposure to the atmosphere that occur in vivo. Contrary to classical cultures performed on plastic dishes covered with culture medium, which show rudimentary differentiation and organization, the architecture of the stratified epithelium obtained in reconstructed cultures and the distribution of differentiation markers such as suprabasal keratins, involucrin, and membrane-bound transglutaminase were similar to those of the epidermis of skin biopsies; moreover, biochemical studies showed that the synthesis of the various keratins and the production of cornified envelopes was similar to what is found with skin specimens. The reconstructed epidermis model was found to be very useful to study in vitro the effect of retinoic acid on keratinocyte differentiation and epidermal morphogenesis.     

Distribution and morphological variation of Streptocephalus torvicornis (Waga, 1842) in Northern Africa

The known range of S. torvicornis is extended to areas of the Western and Central Sahara and Sahel. Morphological variation between populations is important, and cannot be accomodated within the known Iberian and Maghrebian subspecific taxa, which appear untenable. A grouping of populations according to drainage basins appears, however, possible. Populations of the Hoggar, Air, and Tibesti waters, draining towards the Soudanian zone, are more closely related than populations from waters draining towards the Atlantic. Tassili-n-ajjer populations from Central Algeria have individual characteristics, and deserve further study.     

Dormant egg bank characteristics and hatching pattern of the Phallocryptus spinosa (Anostraca) population in the Makgadikgadi Pans (Botswana)

The anostracan Phallocryptus spinosa has an almost exclusively palearctic distribution. The Makgadikgadi Pans area in Botswana represents the only distribution record south of the Sahara. In this ephemeral wetland, it is an important food item in the diet of migrating birds. By studying egg bank characteristics (such as depth and density) and hatching requirements, we investigated the persistence of this sub-Saharan population. At localities in the middle and north basin of Sua Pan, sediment cores were taken along a transect, and dormant eggs were isolated. Densities of the active dormant egg bank ranged from 833 to 31449 dormant eggs m⁻², indicating that this species is well established. Most of the dormant eggs were found in the top 4 cm of the sediments, and densities decreased to zero at a depth of 13 cm. Considering the expected low sedimentation rate, the presence of dormant eggs down to 13 cm indicates long-time occurrence of P. spinosa in the Makgadikgadi Pans area. We observed high hatching fractions (up to 85%) at a temperature of 22 °C and a salinity of 5 ppt. A second anostracan species, Branchinella ornata, co-occurred with P. spinosa in our study site. This population also had a large active dormant egg bank (ranging from 6634 to 50557 dormant eggs m⁻²) with dormant eggs present until a depth of about 11 cm. This pattern indicates a long-time co-occurrence of P. spinosa and B. ornata.     

Studies on the Cytosolic Phospholipase A2 in Immortalized Astrocytes (DITNC) Revealed New Properties of the Calcium Ionophore,A23187

Besides playing an important role in the maintenance of cell membrane phospholipids, phospholipases A₂ (PLA₂) are responsible for the release of arachidonic acid (AA) which is a precursor for prostaglandin biosynthesis. The cytosolic PLA₂ has been the focus of recent studies, probably due to its ability to respond to protein kinases and changes in intracellular calcium levels. In this study, we examined agents for stimulation of the cytosolic phospholipase A₂ in immortalized astrocytes (DITNC). Incubation of DITNC cells with [¹⁴C]arachidonic acid (AA) resulted in a time-dependent uptake of the label into phospholipids (PL) and neutral glycerides. In prelabeled cells, release of labeled AA could be stimulated by calcium mobilizing agents such as calcium ionophore A23187 (4–20 M) and thimerosal (100 M), and by phorbol myristate acetate (PMA, 100 nM), an agent for activation of protein kinase C. The release of AA could also be stimulated by ATP (200 M), probably through activation of the purinergic receptor but not by glutamate (1 mM). The stimulated release of AA was dependent on extracellular Ca²⁺ and was inhibited by mepacrine (50 M), a non-specific PLA₂ inhibitor. Western blot analysis further confirmed the presence of an 85 kDa cPLA₂ in both membrane and cytosol fractions of these cells and stimulation by A23187 resulted in translocation of this protein to the membrane fraction. Besides labeled fatty acids, A23187 also stimulated the concomitant release of labeled PL into the culture medium and this event was accompanied by the increased release in lactate dehydrogenase (LDH). Results thus revealed that besides activation of cPLA₂, the calcium ionophore A23187 is capable of perturbating cell membrane integrity.     

Assessment of all-trans retinoic acid (ATRA) efficacy as a single agent in primary lymphoid neoplasia

All-trans retinoic acid (ATRA) is currently widely used in the therapy of acute promyelocytic leukimia and is being testedin vitro andin vivo on several other malignancies. Previously ATRA has been shown to inhibit the growthin vitro, of established human myeloma cell lines as well as cultured primary myeloma cells from patients. ATRA acts by down-regulating IL-6-receptor-alpha or gp130 on the surface of the myeloma cells. However, despite itsin vitro effects on myeloma cells, ATRA therapy on advanced stage multiple myeloma (MM) patients has so far largely been ineffective. In current studies, we have assessed the efficacy of ATRA therapy against primary murine plasma cell tumors, which are an animal model for human MM. These tumors are induced at about 50% incidence in pristane-primed BALB/c mice by injection ofv-raf/v-myc-containing retroviruses and are IL-6 dependent. Using this animal model, we assessed the effect of ATRA as a therapeutic agent against primary tumors at two early time points in disease development. ATRA was administered in liposomal vesicles (ATRAGEN?), since liposomal-ATRA has been shown to circumvent clearance mechanisms by hepatic microsomes, which normally occur with free ATRA. In addition, ATRAGEN? was previously shown to be less toxic in mice than free ATRA. ATRAGEN? was administered beginning on day 25 or day 45 after virus injection and continued twice weekly for 8–11 weeks. ATRAGEN? administration begun at either time point did not alter the incidence or the latency of plasma cell tumors compared with control animals. These results suggest that ATRA may not be an effective sole therapy against early MM.     

Posteriorization by FGF, Wnt, and retinoic acid is required for neural crest induction.

The neural crest is a unique cell population induced at the lateral border of the neural plate. Neural crest is not produced at the anterior border of the neural plate, which is fated to become forebrain. Here, the roles of BMPs, FGFs, Wnts, and retinoic acid signaling in neural crest induction were analyzed by using an assay developed for investigating the posteriorization of the neural plate. Using specific markers for the anterior neural plate border and the neural crest, the posterior end of early neurula embryos was shown to be able to transform the anterior neural plate border into neural crest cells. In addition, tissue expressing anterior neural plate markers, induced by an intermediate level of BMP activity, was transformed into neural crest by posteriorizing signals. This transformation was mimicked by bFGF, Wnt-8, or retinoic acid treatment and was also inhibited by expression of the dominant negative forms of the FGF receptor, the retinoic acid receptor, and Wnt signaling molecules. The transformation of the anterior neural plate border into neural crest cells was also achieved in whole embryos, by retinoic acid treatment or by use of a constitutively active form of the retinoic acid receptor. By analyzing the expression of mesodermal markers and various graft experiments, the expression of the mutant retinoic acid receptor was shown to directly affect the ectoderm. We thereby propose a two-step model for neural crest induction. Initially, BMP levels intermediate to those required for neural plate and epidermal specification induce neural folds with an anterior character along the entire neural plate border. Subsequently, the most posterior region of this anterior neural plate border is transformed into the neural crest by the posteriorizing activity of FGFs, Wnts, and retinoic acid signals. We discuss a unifying model where lateralizing and posteriorizing signals are presented as two stages of the same inductive process required for neural crest induction.     

Effects of All-trans retinoic acid on germ cell development of embryos and larvae of the giant freshwater prawn, Macrobrachium rosenbergii

Embryos of the giant freshwater prawn, Macrobrachium rosenbergii, were treated with 1, 10 or 50 μg ml⁻¹ all-trans retinoic acid (AtRA) for 2 days. Survival and hatching rates were not affected. However, an increase in the number of primordial germ cells (PGCs), progenitors of gametes, and a slightly more advanced stage of the gonads were found in those treated with 10 or 50 μg ml⁻¹ AtRA. Newly hatched larvae were treated with 0.1, 0.5 or 1 μg ml⁻¹ AtRA for 2 days. Survival rates were lower in those treated with 0.5 or 1 μg ml⁻¹ AtRA; nevertheless, the gonads were slightly more developed. The results indicated that AtRA, an active metabolite of vitamin A, affected germ cell and gonad development of embryos and the larvae of giant freshwater prawn.     

International study on Artemia. LVI. Characterization of two Artemia populations from Namibia and Madagascar: cytogenetics, biometry, hatching characteristics and fatty acid profiles

Two parthenogenetic Artemia populations from southern Africa, one from Swakopmund saltworks (Namibia) and another from Ankiembe saltworks (Madagascar) have been studied. The population from Namibia is mainly diploid (2n=42) with few tetraploid individuals (4n=84), while the one from Madagascar was found to be triploid (3n=63). No chromocenters have been observed in either of the two populations. The Namibian population has smaller cysts and nauplii compared to those of the Madagascar population. Discriminant analysis revealed significant differences in the biometry of the adults from the two populations. The two populations exhibited very good hatching characteristics. The study of fatty acid methyl esters revealed that the Namibian population belongs to the fresh water type of Artemia showing low levels of eicosapentaenoic acid, whereas the population from Madagascar displayed exceptionally high levels of eicosapentaenoic acid, belonging to the marine water type.     

Monoamine oxidase A and B activities in embryonic chick hepatocytes: differential regulation by retinoic acid

Monoamine oxidases (MAOs) A and B are two isoenzymes involved in the degradation of many biological amines in the nervous system and in peripheral organs. In the present work hepatocytes isolated from 14-day-old chick embryos were used as a model system to determine whether retinoic acid (RA) is capable of modulating the activity of the two MAO forms. RA is a retinoid that, by binding with nuclear receptors, interferes with the expression of specific genes in many differentiation processes. Enzymic activity was measured with a radiochemical method using serotonin and beta-phenylethylamine as preferential substrates for MAO A and MAO B, respectively. The specific activity of the two forms was measured in hepatocytes cultured for 24, 48 and 72 h in the presence and the absence of serum. RA stimulated MAO B but not MAO A activity, in a dose- and time-dependent way, and only in the presence of serum. Maximum stimulation (about 3.5-fold) was obtained after treatment with 5 microM RA for 72 h. Kinetic analysis of MAO B activity showed an increase in V(max) in treated hepatocytes (5 microM RA for 72 h) with no change in K(m). In conclusion, the present work shows that RA selectively elicits MAO B activity in cultured chick embryonic hepatocytes, this stimulation requires the presence of some factors present in the serum and is probably due to an increase in the number of enzyme molecules.     

Wall appositions induced by ionophore A 23187, CaCl2, LaCl3, and nifedipine in characean cells

Summary The formation of wall appositions (plugs) by ionophore A 23187, CaCl₂, LaCl₃, and nifedipine was studied in mature internodal cells of characeaen algae. CaCl₂ at concentrations above 10^–2M induces thick fibrillar plugs without callose inNitella flexilis. InChara corallina andNitella flexilis ionophore A 23187 (1.25×10^–5 to 5×10^–5M) and LaCl₃ (7.5×10^–5 to 2.5×10^–4M) cause flat appositions which contain callose and have a more granular structure. Plug formation by ionophore A 23187, CaCl₂, and LaCl₃ is pH-dependent and occurs beneath the alkaline regions of the cell. Nifedipine (10^–4 to 10^–5M) induces plugs inNitella flexilis after previous injury. These callose-containing wall appositions consist of a heterogeneous granular core which is covered by a fibrillar layer. The results of this work are compared with previous studies on wound wall formation and chlortetracycline (CTC)-induced plug formation which reveal that abundant coated vesicles occur only when a thick fibrillar wall layer is formed. Neither LaCl₃ nor nifedipine inhibit the formation of CaCl₂- or CTC-plugs. The unusual effects of these substances, which normally act as Ca²⁺ antagonists and therefore should prevent and not induce plug formation, are discussed. It is suggested that La³⁺ mimicks the effects of calcium and that nifedipine binding to the Ca²⁺ channels is altered in the alkaline regions of characean internodes and allows an influx of Ca²⁺.Abbreviations AFW artificial fresh water - CTC chlortetracycline - DCMU dichlorphenyldimethylurea - DMSO dimethylsulfoxide - EGTA ethyleneglycoltetraacetic acid - MES 2-(N-morpholino) ethanesulfonic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - TAPS N-tris[hydroxymethyl]methyl-3-aminopropanesulfonic acid     

Adsorption of bisphenol A by lactic acid bacteria,Lactococcus, strains

Ten strains of the genus Lactococcus were examined for their ability to remove bisphenol A [2, 2-bis(4-hydroxyphenyl)propane; BPA], which is known as an endocrine disrupter. Nine strains of the lactococci tested could remove BPA from media during growth, although the removal ratio was below 9%. When BPA was incubated with lyophilized cells of lactococci for 1 h, the concentration of BPA in the media was decreased by 9–62%. Especially, the highest removal ratio of BPA was observed for Lactococcus lactis subsp. lactis 712. The lactococci could adsorb BPA but not degrade it, because the lactococci maintained the ability to remove BPA from the medium after autoclaving. When the lyophilized cells of L. lactis subsp. lactis 712 were also incubated with six analogues of BPA, they effectively adsorbed hydrophobic compounds such as 2, 2′-diphenylpropane and bisphenol A dimethylether. The BPA-adsorbing ability of lactococci could be due to the hydrophobic binding effect. The removal ratio of BPA by L. lactis subsp. lactis 712 was increased after treatment with sodium dodecyl sulfate and decreased after digestion with trypsin. These results suggest that the hydrophobic proteins on cell surface may be involved in the BPA-adsorbing ability of lactococci.     

Identification and characterization of the retinoic acid response elements in the human RIG1 gene promoter

The expression of retinoic acid-induced gene 1 (RIG1), a class II tumor suppressor gene, is induced in cells treated with retinoids. RIG1 has been shown to express ubiquitously and the increased expression of this gene appears to suppress cell proliferation. Recent studies also demonstrated that this gene may play an important role in cell differentiation and the progression of cancer. In spite of the remarkable regulatory role of this protein, the molecular mechanism of RIG1 expression induced by retinoids remains to be clarified. The present study was designed to study the molecular mechanism underlying the all-trans retinoic acid (atRA)-mediated induction of RIG1 gene expression. Polymerase chain reaction was used to generate a total of 10 luciferase constructs that contain various fragments of the RIG1 5'-genomic region. These constructs were then transfected into human gastric cancer SC-M1 and breast cancer T47D cells for transactivation analysis. atRA exhibited a significant induction in luciferase activity only through the -4910/-5509 fragment of the 5'-genomic region of RIG1 gene relative to the translation initiation site. Further analysis of this promoter fragment indicated that the primary atRA response region is located in between -5048 and -5403 of the RIG1 gene. Within this region, a direct repeat sequence with five nucleotide spacing, 5'-TGACCTctattTGCCCT-3' (DR5, -5243/-5259), and an inverted repeat sequence with six nucleotide spacing, 5'-AGGCCAtggtaaTGGCCT-3' (IR6, -5323/-5340), were identified. Deletion and mutation of the DR5, but not the IR6 element, abolished the atRA-mediated activity. Electrophoretic mobility shift assays with nuclear extract from atRA-treated cells indicated the binding of retinoic acid receptor (RAR) and retinoid X receptor (RXR) heterodimers specifically to this response element. In addition to the functional DR5, the region contains many other potential sequence elements that are required to maximize the atRA-mediated induction. Taken together, we have identified and characterized the functional atRA response element that is responsible for the atRA-mediated induction of RIG1 gene.     

The effects of retinoic acid on mitosis during tail and limb regeneration in the axolotl larva,Ambystoma mexicanum

Summary Regenerating tails and limbs of axolotl larvae (A. mexicanum) were studied for overall growth and for mitosis after the animals received intraperitoneal injections of all-trans retinoic acid. Both processes were depressed to approximately the same extent (60–70%). Some mitosis always survived, even when the treatment was in effect during the entire history of the regenerate. The treatment duration was a major variable in the severity of the effect, whereas the post-amputation age of the regenerate was not. In limb regenerates the epithelial cap and the mesenchymal blastema were affected to roughly the same degree.Supported by PHS Grant 507RR7031H of the BMRG, Indiana University