Antiproliferative Activity and Ultrastructural Changes in Promastigote and Amastigote forms of Leishmania amazonensis Caused by Limonene-Acylthiosemicarbazide Hybrids

Leishmaniasis is a tropical zoonotic disease. It is found in 98 countries, with an estimated 1.3 million people being affected annually. During the life cycle, the Leishmania parasite alternates between promastigote and amastigote forms. The first line treatment for leishmaniasis are the pentavalent antimonials, such as N-methylglucamine antimoniate (Glucantime®) and sodium stibogluconate (Pentostam®). These drugs are commonly related to be associated with dangerous side effects such as cardiotoxicity, nephrotoxicity, hepatotoxicity, and pancreatitis. Considering these aspects, this work aimed to obtain a new series of limonene-acylthiosemicarbazides hybrids as an alternative for the treatment of leishmaniasis. For this, promastigotes, axenic amastigotes, and intracellular amastigotes of Leishmania amazonensis were used in the antiproliferative assay; J774-A1 macrophages for the cytotoxicity assay; and electron microscopy techniques were performed to analyze the morphology and ultrastructure of parasites. ATZ−S-04 compound showed the best result in both tests. Its IC₅₀, in promastigotes, axenic amastigotes and intracellular amastigotes was 0.35±0.08 μM, 0.49±0.06 μM, and 15.90±2.88 μM, respectively. Cytotoxicity assay determined a CC₅₀ of 16.10±1.76 μM for the same compound. By electron microscopy, it was observed that ATZ−S-04 affected mainly the Golgi complex, in addition to morphological changes in promastigote forms of L. amazonensis.     

Evaluation of Probiotic Properties of Novel Brazilian Lactiplantibacillus plantarum Strains

Probiotics and Antimicrobial Proteins - Beneficial effects of Lactiplantibacillus plantarum strains have been widely reported. Knowing that the effects of probiotic bacteria are strain-dependent,...     

Natural lignin modulators improve bagasse saccharification of sugarcane and energy cane in field trials

The burgeoning cellulosic ethanol industry necessitates advancements in enzymatic saccharification, effective pretreatments for lignin removal, and the cultivation of crops more amenable to saccharification. Studies have demonstrated that natural inhibitors of lignin biosynthesis can enhance the saccharification of lignocellulose, even in tissues generated several months post-treatment. In this study, we applied daidzin (a competitive inhibitor of coniferaldehyde dehydrogenase), piperonylic acid (a quasi-irreversible inhibitor of cinnamate 4-hydroxylase), and methylenedioxy cinnamic acid (a competitive inhibitor of 4-coenzyme A ligase) to 60-day-old crops of two conventional Brazilian sugarcane cultivars and two energy cane clones, bred specifically for enhanced biomass production. The resultant biomasses were evaluated for lignin content and enzymatic saccharification efficiency without additional lignin-removal pretreatments. The treatments amplified the production of fermentable sugars in both the sugarcane cultivars and energy cane clones. The most successful results softened the most recalcitrant lignocellulose to the level of the least recalcitrant of the biomasses tested. Interestingly, the softest material became even more susceptible to saccharification.     

Evaluation of laboratory indexes of absorption of soil phosphorus by plants: II

Summary A comparison was made of several laboratory methods for estimating the yield of phosphorus in plants grown in greenhouse cultures on samples of 22 soils from different parts of the United States. The methods investigated and their rank in order of increasing precision of the estimates of the yield of phosphorus were as follows: extraction with lactic acid, calcium lactate buffer solution extraction with 2 per cent citric acid solution < extraction with 0.03N NH₄F, 0.025N HCl solution < percentage phosphorus saturation (found as follows: 100 × labile phosphorus by isotopic dilution/ phosphorus adsorption capacity according to Langmuir adsorption equation) labile phosphorus by isotopic dilution phosphorus extracted by water.Journal Paper No. J-3747 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No. 1183. Contribution from the Department of Agronomy.     

ROOT PROFILES AND COMPETITION BETWEEN THE INVASIVE,EXOTIC PERENNIAL,CARPOBROTUS EDULIS,AND TWO NATIVE SHRUB SPECIES IN CALIFORNIA COASTAL SCRUB

The mat-forming succulent, Carpobrotus edulis (Aizoaceae), surrounds and grows over many native plant species in California coastal communities. Two shrub species, Haplopappus ericoides and H. venetus var. sedoides, were found to have shallow root systems that occupied the same soil depths as those of C. edulis. In the presence of C. edulis, the normal rooting profiles of the shrubs were displaced downward, although partial overlap with C. edulis remained. Removal of C. edulis from around individuals of both shrub species resulted in higher predawn xylem pressure potentials in shrubs from the removal treatments as compared to controls, suggesting that the surrounding C. edulis was utilizing water that would otherwise have been available to these shrubs. In H. ericoides, predawn xylem pressure potentials of removal treatment shrubs remained higher than those of the controls throughout the remainder of the dry season even though these shrubs showed a marked increase in canopy area after removal of surrounding C. edulis. Removal of C. edulis from around H. venetus also initially led to higher predawn xylem pressure potentials in the removal shrubs as compared to the controls and increased production of new leaves. After this initial period the predawn xylem pressure potentials of the removal shrubs were not significantly different from those of controls, suggesting that the demand for water by the increased leaf areas eventually matched the enhanced water availability resulting from C. edulis removal. Also, the morphology of H. venetus shrubs changed to that more typical of unaffected individuals. Thus, C. edulis significantly affected not only the water relations of these two shrub species but also their shoot sizes and overall morphologies.     

Differentiation in sex investment by clones and populations of Daphnia

Dormancy is an ecological strategy by which organisms avoid stressful environments, but it also can have genetic consequences. Many facultative parthenogens shift from asexual to sexual reproduction to enter dormancy. Hence, conditions that favour dormancy are predicted to select for more sex, which should increase clonal diversity. We examined lake populations of Daphnia that face different ecological risks to remaining active year‐round, and quantified the extent to which they have differentiated in their investment in dormancy and sex. There was substantial genetic variation among populations and clones for sex induction and production of dormant eggs, and striking evidence of gender specialization. We also observed a positive association between the magnitudes of population‐level investment in dormancy and of variance among clones in sex induction. These results document an ecological gradient in dormancy that is manifest as a genetic gradient in clonal variation for the propensity to engage in sex.     

Exploiting the complete yeast genome sequence

The completion of the genome sequence of the budding yeast Saccharomyces cerevisiae marks the dawn of an exciting new era in eukaryotic biology that will bring with it a new understanding of yeast, other model organisms, and human beings. This body of sequence data benefits yeast researchers by obviating the need for piecemeal sequencing of genes, and allows researchers working with other organisms to tap into experimental advantages inherent in the yeast system and learn from functionally characterized yeast gene products which are their proteins of interest. In addition, the yeast post-genome sequence era is serving as a testing ground for powerful new technologies, and proven experimental approaches are being applied for the first time in a comprehensive fashion on a complete eukaryotic gene repertoire.     

Development of the Predatory Stinkbug Brontocoris tabidus Signoret Heteroptera: Pentatomidae on Different Proportions of an Artificial Diet and Pupae of Tenebrio molitor L. Coleoptera: Tenebrionidae

The development of the Neotropical predatory pentatomid Brontocoris tabidus on an artificial diet based on beef meat and liver was evaluated. The predator showed significantly longer nymphal development and lower adult weights on this diet than when reared on pupae of the mealworm Tenebrio molitor. The survival of nymphs fed exclusively on the artificial diet was somewhat lower compared with feeding on T. molitor pupae. When B. tabidus was bred on this artificial diet during part of its nymphal period i.e. during the second; second and third; and second, third and fourth instars , and was subsequently returned to T. molitor pupae, the predator nymphs completed the nymphal stage with a developmental rate similar to that of nymphs fed on live prey throughout. The adults attained after switching from the artificial diet to live prey from the third and fourth instar onwards had similar weights to those in the control. Considering the relatively good results obtained with B. tabidus and other members of the pentatomid subfamily Asopinae, this meat-based diet may be a valuable alternative for use in the mass production of predatory pentatomids.     

Nuclear counterparts of the cytoplasmic mitochondrial 12S rRNA gene: A problem of ancient DNA and molecular phylogenies

Monkey mummy bones and teeth originating from the North Saqqara Baboon Galleries (Egypt), soft tissue from a mummified baboon in a museum collection, and nineteenth/twentieth-century skin fragments from mangabeys were used for DNA extraction and PCR amplification of part of the mitochondrial 12S rRNA gene. Sequences aligning with the 12S rRNA gene were recovered but were only distantly related to contemporary monkey mitochondrial 12S rRNA sequences. However, many of these sequences were identical or closely related to human nuclear DNA sequences resembling mitochondrial 12S rRNA (isolated from a cell line depleted in mitochondria) and therefore have to be considered contamination. Subsequently in a separate study we were able to recover genuine mitochondrial 12S rRNA sequences from many extant species of nonhuman Old World primates and sequences closely resembling the human nuclear integrations. Analysis of all sequences by the neighbor-joining (NJ) method indicated that mitochondrial DNA sequences and their nuclear counterparts can be divided into two distinct clusters. One cluster contained all temporary cytoplasmic mitochondrial DNA sequences and approximately half of the monkey nuclear mitochondriallike sequences. A second cluster contained most human nuclear sequences and the other half of monkey nuclear sequences with a separate branch leading to human and gorilla mitochondrial and nuclear sequences. Sequences recovered from ancient materials were equally divided between the two clusters. These results constitute a warning for when working with ancient DNA or performing phylogenetic analysis using mitochondrial DNA as a target sequence: Nuclear counterparts of mitochondrial genes may lead to faulty interpretation of results.Correspondence to: A.C. van der Kuyl