Human dental microwear caused by calcium oxalate phytoliths in prehistoric diet of the lower Pecos region,Texas

Recent research demonstrates that silica phytoliths of dietary origin are associated with microwear of human teeth. Previous research has shown that severe enamel microwear and dental wear characterizes Archaic hunter-gatherers in the lower Pecos region of west Texas. Calcium oxalate crystals are especially common in Archaic coprolites. The vast majority are derived from prickly pear and agave, which were the dietary staples in west Texas for 6,000 years. The calcium oxalate phytoliths are harder than enamel. Therefore, calcium oxalate crystals are the most likely source of previously documented dental microwear and wear in the lower Pecos region. Am J Phys Anthropol 107:297–304, 1998. © 1998 Wiley-Liss, Inc.     

Red rot resistance in interspecific protoplast fusion product progeny of Porphyra yezoensis and P. tenuipedalis (Bangiales, Rhodophyta)

Nine primary regenerants were recovered by interspecific protoplast fusion of Porphyra yezoensis Ueda T‐14 (Py) (cultivated Porphyra) and Porphyra tenuipedalis Miura (Pt). This combination is difficult to achieve with conventional sexual hybridization, yet is important in that non‐cultivated P. tenuipedalis is partially resistant (PR) to red rot disease, caused by the microbial pathogen, Pythium porphyrae Takahashi et Sasaki. Out of the nine primary regenerants, two strains (Py‐Pt‐4 and Py‐Pt‐7) were like the parent, P. tenuipedalis, while the rest were like the other cultivated parent P. yezoensis T‐14 in their life cycle. Red rot resistance was assessed in parents and interspecific fusion product progeny (FPP) by exposing the foliose thalli to equivalent infection and measuring two parameters of the host‐pathogen interactions: supported fungal biomass and amount of disease produced. Intermediate resistance between P. yezoensis T‐14 (1.00) and P. tenuipedalis (0.13) was observed in two of the Py‐type FPP, Py‐Pt‐2F₂ (0.25) and Py‐Pt‐5F₂ (0.23). Stable inheritance of resistance was observed through two subsequent generations. The morphologic and reproductive characteristics of the regenerated foliose thalli, and nature of host‐pathogen interactions were used to further verify the hybrid origin of the FPP. Host‐pathogen interactions were followed using epi‐fluorescence and scanning electron microscopy (SEM). The zoospores encysted at higher rates on the susceptible cultivated parent (P. yezoensis T‐14) germinated immediately and the short germ tubes formed appres‐soria and penetrated the algal cells near the site of encystment. While on the PR parental (P. tenuipedalis) and partially resistant FPP (PRFPP) progeny (Py‐Pt‐2F₂ and Py‐Pt‐5F₂) the low rate of zoospore encystment was followed by cyst germination, but only a few of the germ tubes formed appressoria and penetrated the thallus surface. Long germ tubes (with no appressoria) were seen growing on the thallus surface without host penetration. The minimal rate of encystment concomitant with low rate of appressorium formation on the PR parent and PRFPP was observed as the major factor responsible for the partial resistance in these thalli.     

Effects of dietary probiotic supplementations on prevention/treatment of yersiniosis disease

Aims:  To evaluate Enterobacter cloacae and Bacillus mojavensis , isolated from rainbow trout gut in the present study, as a probiotic to control yersiniosis disease.
Methods and Results:  A strain of Ent. cloacae and B. mojavensis , isolated from the digestive tract of rainbow trout had an antagonistic effect to Yersinia ruckeri , which causes yersiniosis. After feeding fish with 1 × 10⁸ cells g⁻¹ probiotic containing feed for 60 days, the fish survival rate increased to 99·2% following challenge with Y. ruckeri compared with controls that had 35% survival rate. Effects of Ent. cloacae and B. mojavensis on weight gains and stimulation of red blood cells, white blood cells, platelets and hemoglobin were also evaluated in separate groups of fish fed probiotic containing feed for 2 months. Probiotic significantly affected white blood cells, hemoglobin and weight gains of the experimental fish.
Conclusions:  Enterobacter cloacae and B. mojavensis , can be used to prevent and control yersiniosis disease.
Significance and Impact of the Study:  In conclusion, concomitant use of Ent. cloacae and B. mojavensis as a feed supplement is beneficial to rainbow trout. Use of these organisms can protect fish from yersiniosis and enhance digestibility and utilization of feed. Use of such probiotics may also limit the use of antibiotics and other chemicals in control and treatment of diseases, and thus contribute to the effort to reduce environmental contamination by residual antibiotics and chemicals .     

Target cell deformability determines the type of phagocytic mechanism used by Entamoeba histolytica-like,Laredo strain

Summary— Morphological study of red blood cell phagocytosis by Entamoeba histolytica-like (Laredo strain) has shown that this amoeba is able to ingest by two distinct mechanisms. One is classical phagocytosis and the other is by suction or microphagocytosis. Rigidification of red blood cells by treatment with glutaraldehyde shows that there is a correlation between the deformability of the ingested cell and the type of phagocytosis observed. Indeed, as the red cells become more rigid, less microphagocytosis is observed. To demonstrate that this shift in phagocytic mechanisms is not induced by the modification of a surface receptor by the glutaraldehyde treatment, the amoebas were fed with erythrocyte ghosts. Since these have lost most of their hemoglobin content, they are less rigid than the intact erythrocytes. The ghosts, even after glutaraldehyde treatment, are always ingested by microphagocytosis. These results have therefore led us to conclude that the type of erythrocyte phagocytosis used by E histolytica-like (Laredo strain) is determined by the deformability of the targetted red blood cells.     

Biochemical and ecological characterization of two peroxidase isoenzymes from the mangrove, Rhizophora mangle

This study examines phenolic peroxidase (POX) in Rhizophora mangle L. leaves in order to assess its role in phenolic manipulation and H₂O₂ scavenging. Sun-exposed and understorey leaves experiencing varying degrees of nutrient stress were analysed from an oligotrophic cay off the coast of Belize. POX activity was unaffected by growth environment, but increased throughout leaf development and persisted through senescence and after abscission. Histochemical analyses indicated POX activity throughout leaf tissues, especially in the apoplast. Phenolics were similarly broadly distributed. Two isoenzymes of POX were partially characterized with pIs of 4.1 and 6.3 and masses of 65.5 and 54.3 kDa, respectively. The larger, more acidic isoenzyme showed especially high heat stability, showing no reduced activity after 24 h at 60 °C. Rhizophora mangle POX oxidized quercetin preferentially, and, to a lesser extent, coniferyl alcohol, caffeic acid, chlorogenic acid, and p-coumaric acid. It did not oxidize ascorbate, but ascorbate could act as a secondary electron donor in the presence of a phenolic substrate and H₂O₂. However, because quercetin and other aglycones were not present in R. mangle leaves, and because POX showed no activity with the most abundant leaf flavonoid, rutin, it was concluded that detoxification of H₂O₂ is secondary to the other roles of POX in manipulation of phenolics.     

Ontogenetic changes of circulating erythroid cells and haemoglobin components in Esox lucius

Using light microscopy the morphology, the mitotic index and levels of erythroid cell types were detected from 48 h pike Esox lucius embryos before hatching to adult specimens. At the same developmental stages, the haemoglobins and globin chains expressed were electrophoretically characterized. The erythroid cells of the primitive generation were the most abundant from 48 h before hatching until 15–20 days after hatching, then their number decreased and only rare cells remained in the 3 month‐old juvenile specimens. These cells divided and differentiated in the blood and were substituted by the definitive erythrocyte series. As in other vertebrates, the immature cells of the two generations differed in morphological properties and in the synthetized haemoglobin. The circulating erythroid cells of the definitive population cell lineage were, at all differentiation stages, smaller than those of the primitive generation. The definitive erythrocytes appeared in blood smears of 7 days post‐hatching larvae, they increased rapidly and at 20 days they represented the predominant red blood cell population in the circulation of young pike. Electrophoretic analysis of haemolysates obtained from different developmental stages indicated the presence of distinct embryonic, larval and adult haemoglobins. The embryonic haemoglobins differed from those of the older larva and juvenile specimens and were detectable within the first week of post‐hatching development when only primitive erythrocytes were present in the blood.     

Protective effects of sodium orthovanadate in diabetic reticulocytes and ageing red blood cells of Wistar rats

The reticulocytes and the ageing red blood cells (RBCs) namely young (Y), middle-aged (M) and old RBCs (O) of female Wistar rats from different groups such as control animals (C), controls treated with vanadate (C + V), alloxan-induced diabetic (D), diabetic-treated with insulin (D + I) and vanadate (D + V), were fractionated on a percoll/BSA gradient. The following enzymes were measured-hexokinase (HK), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), glutathione-s-transferase (GST), alanine aminotransferase ΜlaAT), aspartate aminotransferase ΜsAT) and arginase in the hemolysates of all the RBCs fractions. Decreases in the activity of HK and AsAT by about 70%, arginase and GSH-Px by 30% in old RBCs were observed in comparison to reticulocytes of control animals. Increases in the activity of GSSG-R by 86%, AlaAT by more than 400% and GST by 70% were observed in old RBCs in comparison to reticulocytes of control animals. Alloxan diabetic animals showed a further decrease in the activities of HK in Y RBCs by 37%, M RBCs by 39% and O RBCs by 32%, GSH-Px activity in Y RBCs by 13%, M RBCs by 20% and O RBCs by 33% and GST activity in Y RBCs by 14%, M RBCs by 42% and O RBCs by 60% in comparison to their corresponding cells of control animals. An increase in the activity of all the enzymes studied was also observed in reticulocytes of diabetic animals in comparison to reticulocytes of controls. The GSSG-R activity was found to be increased in Y RBCs by 49%, M RBCs by 67% and O RBCs by 64% as compared to the corresponding age-matched cells of control animals. The activity of arginase also decreased in Y RBCs by about10%, M RBCs by 20% and O RBCs by 30% in comparison to the age-matched cells of control animals. A decrease in the activity of AsAT in Y and M RBCs by 30%, and O RBCs by 25% was observed in diabetic animals in comparison to the agematched cells of control animals. The activity of AlaAT was found to be decreased by more than 10% in Y and M RBCs and 25% in O RBCs of diabetic animals in comparison to the age-matched cells of control animals. Insulin administration to diabetic animals reversed the altered enzyme activity to control values. Vanadate treatment also reversed the enzyme levels except for that of GST in old cells     

Larval RNAi in <Emphasis Type="Italic">Tribolium</Emphasis> (Coleoptera) for analyzing adult development

We report here on the use of RNA interference (RNAi) to create pupal and adult loss-of-function phenotypes in the red flour beetle, Tribolium castaneum, by injection of double-stranded RNA (dsRNA) into late instar larvae (we refer to this method as larval RNAi). RNAi is well-established as a useful method to mimic loss-of-function phenotypes in many organisms including insects. However, with a few exceptions (such as in the fruit fly Drosophila melanogaster), RNAi analysis has usually been limited to studies of embryogenesis. Here we demonstrate that injection of green fluorescent protein (GFP) dsRNA into the larval body cavity can inhibit GFP expression beginning shortly after injection and continuing through pupal and adult stages. RNAi analysis of the Tc-achaete-scute-homolog (Tc-ASH) revealed that larval RNAi can induce morphological defects in adult beetles, and also that larval RNAi affects the entire body rather than being localized near the site of injection. The larval RNAi technique will be useful to analyze gene functions in post-embryonic development, giving us the opportunity to study the molecular basis of adult morphological diversity in various organisms.Edited by D. Tautz     

The ultrastructure of the cyst wall of Giardia lamblia

Giardiasis is the most common human protozoal infection. In their cystic phase, giardias are protected from the environment by a filamentous cyst wall made up of carbohydrates, proteins, and by two outer membranes separated from the plasma membrane of the parasite by a peripheral space. The present transmission electron microscope observations of G. lamblia cysts of human origin suggest that the extracellular peritrophic space originates from the growth, elongation, and fusion of large cytoplasmic vacuoles. As the large clear vacuoles grew in size, flattening against the inner face of the plasma membrane, they formed a single vacuole that surrounded the body of the parasite, eventually forming two outer membranes. In mature Giardia cysts, the original plasma membrane of the trophozoite becomes the outermost membrane of the cyst wall (CM1). The large vacuoles form a second membrane surrounding the cyst (CM2), and also form a third membrane (CM3), that becomes the new plasma membrane of the trophozoite. During excystation CM1 and CM2 attach to each other and fragment, leaving abundant membrane residues in the peritrophic space. Knowledge of the biochemical composition and functional properties of the complex outer membranous system of G. lamblia cysts here described will be of use to understand the survival of Giardia cysts in the environment, a major factor responsible for the high prevalence of giardiasis worldwide.