Threatened fishes of the world: <Emphasis Type="Italic">Menidia riojai</Emphasis> Solórzano and López 1965 (Atheriniformes: Atherinopsidae)

Menidia riojai is endemic of the Lerma River headwaters considered critically endangered because its populations have been severely fragmented.     

Plasma iron is associated with lipid peroxidation in an elderly population

Epidemiological evidence has raised concern that a moderate elevation in body iron stores may increase oxidative stress and risk of heart disease. We examined the cross-sectional association between plasma iron and factors that could affect its levels (antioxidant enzymes, diet), with the concentration of plasma malondialdehyde (MDA) as a marker of lipid peroxidation. Participants were 162 non-smoking institutionalised elderly. Our results show that those in the highest tertile of plasma iron were at least twice as likely to have higher plasma MDA levels. Among the factors affecting plasma iron levels, we found that the upper tertile of erythrocyte-superoxide dismutase (E-SOD) was inversely associated with higher plasma iron, and potato intake explained a sizeable proportion of the variation in plasma iron levels. In addition to potatoes, eggs, wine, fruit in men and green vegetables in women showed a positive association with plasma iron levels. Only potatoes in both sexes, wine in men and eggs in women had an independent effect on plasma MDA. Potatoes, wine, plasma lycopene and plasma iron accounted for 43% of the variability in plasma MDA for males, and E-SOD, potatoes, eggs, plasma lycopene and plasma iron explained 45% for women. A longitudinal study should confirm, whether these MDA levels are related to morbidity and mortality.     

Potential effects of El Niño-South Oscillation (ENSO) on growth of the American crocodile, Crocodylus acutus (Crocodylia: Crocodilydae) in captivity

Temperature affects growth rate of crocodiles. However, no information exists about the effects of temperature by El Niño-South Oscillation (ENSO) on crocodiles. In this paper, we present information about the effect of ENSO on total length and body mass of Crocodylus acutus in captivity during 1997–2001. We did not observe differences in total length among years, but we did so in body mass. Furthermore, we observed that warm episodes of ENSO were associated with a higher average total length and cold episodes represented a higher average of body mass. Sea surface temperature (SST) was significantly related with total length; however, the relationship between SST and body mass was unclear. We suggest that ENSO effects on growth rates of crocodiles need to be considered as an important factor on the management of captive populations.     

Ovarian and Uterine Ultrasonography in <Emphasis Type="Italic">Aotus azarai infulatus</Emphasis>

We evaluated the uterus and ovaries of owl monkeys (Aotus azarai infulatus) via gynecological ultrasound examination. We evaluated the subjects in 2 different time periods. The first period (P1) was characterized by the absence of mating, with daily examinations, during 4 mo (n = 10). At the end of P1, we paired the subjects for 30 d, but without ultrasonographic evaluation. The second period (P2) was characterized by the presence of mating, with examinations once a week, during 7 consecutive months (n = 9). We evaluated the uterus and ovaries in sagittal and transverse scans, using a 5–12 MHz linear array probe. The uterine volume (UV) was directly proportional to the number of previous parturitions. The right ovary volume (RtOV) is greater than the left (LtOV) in P1 and P2. There is a positive correlation (p < 0.05) between the females’ mass, RtOV (r = 0.28) and LtOV (r = 0.16).     

Regucalcin is under‐expressed in human breast and prostate cancers: Effect of sex steroid hormones

Regucalcin plays an important role in maintenance of intracellular Ca²⁺ homeostasis, suppresses cell proliferation, inhibits expression of oncogenes, and increases the expression of tumour suppressor genes. This suggests that regucalcin functions may be altered in cancer tissues. In this study the regucalcin expression in breast and prostate cancer cases was analysed by RT‐PCR and immunohistochemistry showing that the mRNA and/or protein are under‐expressed in these tumors. The effect of sex steroid hormones on regucalcin expression in breast and prostate cancer cells was determined by real‐time PCR. MCF‐7 and LNCaP cells were stimulated with 0, 1, and 10 nM of 17β‐estradiol (E₂) or 5α‐dihydrotestosterone (DHT), respectively, for 0, 6, 12, 24, and 48 h. MCF‐7 cells were also stimulated with E₂ conjugated to BSA (E₂‐BSA). To explore the mechanisms underlying the sex steroid regulation of regucalcin expression, control treatments with ICI 182,780, flutamide and cyclohexamide were carried out. E₂ effects regulating regucalcin expression were not abrogated in the presence of ICI 182,780, and were similar to those observed with E₂‐BSA, which suggests the involvement of a membrane‐bound estrogen receptor. In LNCaP cells, DHT down‐regulated regucalcin expression, an effect inhibited by the presence of both flutamide and cyclohexamide, suggesting the involvement of androgen receptor and de novo protein synthesis. The loss of regucalcin expression in breast and prostate cancer cases and the regulation of its expression by sex steroid hormones suggest that it may be associated with development and progression of these human tumors. J. Cell. Biochem. 107: 667–676, 2009. © 2009 Wiley‐Liss, Inc.     

Analyses of Mechanisms for Force Generation During Cell Septation in Escherichia coli

Escherichia coli is a rod-shaped bacterium that divides at its midplane, partitioning its cellular material into two roughly equal parts. At the appropriate time, a septum forms, creating the two daughter cells. Septum formation starts with the appearance of a ring of FtsZ proteins on the cell membrane at midplane. This Z-ring causes an invagination in the membrane, which is followed by growth of two new endcaps for the daughter cells. Invagination occurs against a cell overpressure of several atmospheres. A model is presented for the shape of the cell as determined by the tension in the Z-ring. This model allows the calculation of the force required for invagination. Then three possible models to generate the force necessary to achieve invagination are presented and analyzed. These models are based on converting GTP-bound FtsZ polymeric structures to GDP-bound FtsZ structures, which then leave the polymer. Each model is able to generate the force by relating the hydrolyzation to an irreversible molecular binding event, resulting in a net motion of putative anchors for the structures. All three models show that cross-linking the FtsZ protofilaments into a polymer structure allows the removal of GDP-FtsZ without interrupting the structure during force generation, as would happen for a simple polymeric chain. This work is a partially the result of an Undergraduate Research Project (OS and RT). The support of the National Science Foundation Division of Mathematical Sciences and Division of Biological Sciences through Grant DMS 0214585 and a Supplement to support Undergraduate Research in Biology and Mathematics is appreciated.     

The Effects of Bacterial Leaching on Metal Partitioning in Sewage Sludge

The partitioning of Mn, Al, Zn, Cu and Ti ions in municipal sewage sludge was investigated before and after bioleaching processes effectuated by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Oxidation–reduction potential increase and pH decrease were obtained as a result of bacterial activity. A less pronounced and constant decrease was obtained with A. ferrooxidans, whereas A. thiooxidans presented a lag phase before a steep pH decrease. Metal solubilization was accomplished in experimental systems supplemented with energy source, Fe²⁺ for A. ferrooxidans and S⁰ for A. thiooxidans. Solubilization efficiency differed for each metal except for Al, and was relatively similar for either organism. Metal partitioning was conducted using a five-step sequential extraction procedure before and after the bioleaching. The results indicated that Zn and Mn ions were mostly associated with the organic fraction, whereas Cu, Al and Ti ions with the sulphide/residue fraction. The bioleaching process caused prompt solubilization of metals mostly associated with the more labile fractions (exchangeable, adsorbed and organically bound metals), whereas those associated to the less labile ones (EDTA and sulphide/residue fractions) were exchanged towards more labile fractions.     

The disease resistance gene Dm3 is infrequent in natural populations of Lactuca serriola due to deletions and frequent gene conversions at the RGC2 locus

Resistance genes can exhibit heterogeneous patterns of variation. However, there are few data on their frequency and variation in natural populations. We analysed the frequency and variation of the resistance gene Dm3, which confers resistance to Bremia lactucae (downy mildew) in 1033 accessions of Lactuca serriola (prickly lettuce) from 49 natural populations. Inoculations with an isolate of Bremia lactucae carrying avirulence gene Avr3 indicated that the frequency of Dm3 in natural populations of L. serriola was very low. Molecular analysis demonstrated that Dm3 was present in only one of the 1033 wild accessions analysed. The sequence of the 5' region of Dm3 was either highly conserved among accessions, or absent. In contrast, frequent chimeras were detected in the 3' leucine-rich repeat-encoding region. Therefore low frequency of the Dm3 specificity in natural populations was due to either the recent evolution of Dm3 specificity, or deletions of the whole gene as well as variation in 3' region caused by frequent gene conversions. This is the most extensive analysis of the prevalence of a known disease resistance gene to date, and indicates that the total number of resistance genes in a species may be very high. This has implications for the scales of germplasm conservation and exploitation of sources of resistance.