Effect of progesterone from induced corpus luteum on the characteristics of a dominant follicle in dromedary camels (Camelus dromedarius)

The present study was carried out to elucidate the effect of progesterone (P4) from the induced corpus luteum (CL) on the characteristics of the dominant follicle (DF) in dromedary camels (Camelus dromedarius). Ovarian follicular and induced CL dynamics were monitored by transrectal ultrasonography in eight camels during the peak breeding season. The characteristics of the DF were monitored daily from the day of emergence into a wave, until it appeared to lose its dominance and the DF of a subsequent wave grew to a diameter of 13-17 mm. At this stage ovulation was induced by hCG and the DF was monitored every 8 h for 48 h. After ovulation, CL dynamics and follicular development (emergence of a new wave, growth and mature phase of the selected DF) were monitored daily. Blood samples were collected during each ultrasound examination to study the P4 profile in these animals. The CL developed to a maximum size (22.55 ± 3.24 mm) with a peak concentration of P4 (4.60 ± 2.57 ng/ml) 7 days after ovulation. The size of the CL was positively correlated with the P4 concentration (r = 0.612) during the different stages of the CL dynamics. The presence of CL did not affect the linear growth rate, duration of growth and mature phases of the DF. The development of the DF to its maximum size during its mature phase and inter-wave interval were not affected by the P4 secreted by the induced CL. In conclusion, there is no evidence from this study to suggest that P4 from induced CL altered the characteristics of a DF in dromedary camels.     

Glycosphingolipid expression in pig aorta: identification of possible target antigens for human natural antibodies

Total non-acid glycosphingolipids were isolated from the aortas of more than 80 pigs. The glycolipids were separated by HPLC, analysed by thin- layer chromatography, and tested for reactivity with monoclonal anti- blood group antibodies. The fractions were structurally characterized by NMR spectroscopy and mass spectrometry. Reactivity with both anti- blood group A and H antibodies was seen. The major glycosphingolipid constituents were globotri- and globotetraosylceramides and blood group H pentaglycosylceramides based on type 1 and type 2 core saccharide chains. Globopentaosylceramides, blood group H hexaglycosylceramides based on type 4 chain, and blood group A hexaglycosylceramides based on type 1 core chain were also present. Two structures, that may be important targets for human antibodies initiating hyperacute rejection following pig to human xenotransplantation, were present as minor constituents compared to the blood group components. These were Galalpha1,3neolactotetraosylceramide and a Galalpha1, 3Lexstructure. A Leb/Y hexaglycosylceramide was also present.      

Trichoderma spp. and Bacillus spp. as growth promoters in maize (Zea mays L.)

Microbes that are beneficial to plants are used to enhance the crop growth, yield and are alternatives to chemical fertilizers. Trichoderma and Bacillus are the predominant plant growth-promoting fungi and bacteria. The objective of this study was select, characterize, and evaluate isolates of Trichoderma spp. and Bacillus spp. native from the northern region of Sinaloa, Mexico, and assess their effect on growth promotion in maize (Zea mays L.). In greenhouse conditions, four Trichoderma isolates and twenty Bacillus isolates, as well as two controls, were tested in a completely randomized design with three replicates. We selected the two best strains of Trichoderma and Bacillus: TB = Trichoderma asperellum, TF = Trichoderma virens, B14 = Bacillus cereus sensu lato and B17 = Bacillus cereus, which were evaluated in the field in a completely randomized blocks in factorial arrangement design with three replicates applying different rates of nitrogen fertilizer (0, 150 kg N/ha, and 300 kg N/ha). Treatments 5 (B17 = B. cereus) and 11 (TF = T. virens) both fertilized with 150 kg N/ha showed similar yields and they did not reveal significant differences from the treatments fertilized with 300 kg N/ha. This indicated that treatment 5 (B17= B. cereus with 150 kg N/ha) and treatment 11 (TF= T. virens with 150 kg N/ha) were efficient as growth promoters, by not showing significant differences in root volume and dry weight of foliage. The results indicated a reduction of 50% in the rate of nitrogen to fertilizer required for maize (Zea mays L.) crops. These microorganisms Trichoderma and Bacillus could be an alternative to reduce the use of chemical fertilizers in maize.     

Glutathione selectively inhibits Doxorubicin induced phosphorylation of p53Ser, caspase dependent ceramide production and apoptosis in human leukemic cells

Glutathione (GSH) is the most abundant non-protein antioxidant in mammalian cells. It has been implicated in playing an important role in different signal transduction pathways, and its depletion is an early hallmark in the progression of apoptosis in response to a number of proapoptotic stimuli. We have selectively investigated the role of GSH in cytotoxic response of Jurkat and Molt-4 human leukemic cells to the anti-cancer drug Doxorubicin. In this study, we have shown that extracellular supplementation of GSH to human leukemic cells renders them a resistant phenotype to Doxorubicin treatment. Glutathione pre-treatment inhibits Doxorubicin-induced p53Ser¹⁵ phosphorylation, caspase dependent ceramide (Cer) generation, Poly (ADP-ribose) polymerase (PARP) cleavage, and DNA fragmentation. Taken together, these results indicate that the major cellular antioxidant GSH influences the chemotherapeutic efficacy of Doxorubicin towards human leukemic cells.     

HOW AND WHEN DO LAMBS RECOGNIZE THE BLEATS OF THEIR MOTHERS?

ABSTRACT

In domestic sheep Ovis aries, the mother and the young display a preferential bond for each other that relies on multimodal inter-individual recognition. Lambs show a preference for their own dam shortly after birth, and this is important for their survival. The role of acoustic cues in this early preference for the mother is not clear. The aim of the present work was to analyze the timing of acoustic recognition of the mother and to identify the physical parameters used in the recognition of maternal bleats by the lamb.

In a first study, we investigated the ability of lambs to discriminate between the bleats of their own mother and an alien equivalent mother in a two-choice test. Both ewes were hidden behind a canvas sheet and lambs were not allowed to approach the dams closer than 1 m, thus preventing visual as well as olfactory perception. Tests were conducted 12 hr, 24 hr or 48 hr after birth (n=19 or 20/group). An indication of vocal discrimination was already present at 24 hr and at 48 hr lambs spent significantly more time near their mother than near the alien dam.

In a second step, we investigated which physical parameters of the bleats were important for recognition. For this, we conducted playback experiments with modified bleats at two weeks postpartum. Ours results show that lambs pay attention to a combination of various time, energy and frequency parameters: timbre (distribution of energy within the spectrum), amplitude and frequency modulations appear to be the most important parameters encoding the individual signature.

We conclude that vocal recognition between the ewe and her lamb plays an important role in the display of preferential mother-young bond from very early on. Our studies also demonstrate that the encoding of the individual signature is not limited to the frequency domain but rather involves a multiparametric encoding process.     

Nile perch and the transformation of Lake Victoria

The transformation of Lake Victoria that began in 1980 followed the population explosion of Nile perch Lates niloticus, causing the apparent extirpation of 500+ endemic haplochromine species and dramatic physico-chemical changes. Officially introduced in 1962–1963, but present earlier, the reasons for the long delay before its population exploded are discussed. The hypothesis that it occurred only after the haplochromine decline is evaluated, but haplochromines declined only after the Nile perch expansion began. The sudden eutrophication of the lake was attributed to Nile perch, but evidence of eutrophication from 1950 onwards led some researchers to conclude that it was the result of climatic changes. We conclude that the haplochromine destruction disrupted the complex food webs that existed prior to the upsurge of Nile perch. The depletion of fish biomass by Nile perch may have been the source of extra phosphorus responsible for the eutrophication of the lake. After the Nile perch explosion in 1980 the fish population came to be dominated by only three species, but fisheries productivity increased at least 10-fold. Fishing has caused demographic changes in Nile perch, which may have allowed some haplochromine species to recover. The condition of the lake appears to have stabilised since 2000, partly because the fish biomass has risen to at least 2 × 10⁶ t, replacing the ‘lost’ biomass and restoring some ecosystem functioning.     

A reassessment of decreased amino acid accumulation by ehrlich ascites tumor cells in the presence of metabolic inhibitors

This study was undertaken to examine the mechanism by which metabolic inhibition reduces amino acid active transport in ehrlich ascites tumor cells. At 37 degrees C the metabolic inhibitor combination 0.1 mM 2,4-dinitrophenol (DNP) + 10 mM 2- deoxy-D-glucose (DOG) reduced the cell ATP concentration to 0.10- 0.15 mM in less than 5 min. This inhibition was associated with a 20.6 percent +/- 6.4 percent (SD) decrease in the initial influx of α-aminoisobutyric acid (AIB), and a two- to fourfold increase in the unidirectional efflux. These effects could be dissociated from changes in cell Na(+) or K(+) concentrations. Cells incubated to the steady state in 1.0-1.5 mM AIB showed an increased steady-state flux in the presence of DNP + DOG. Steady- state fluxes were consistent with trans-inhibition of AIB influx and trans-stimulation of efflux in control cells, but trans- stimulation of both fluxes in inhibited cells. In spite of the reduction of the cell ATP concentration to less than 0.15 mM and greatly reduced transmembrane concentration gradients of Na(+) and K(+), cells incubated to the steady state in the presence of the inhibitors still established an AIB distribution ration 13.8 +/- 2.6. The results are interpreted to indicate that a component of the reduction of AIB transport produced by metabolic inhibition is attributable to other actions in addition to the reduction of cation concentration gradients. Reduction of cell ATP alone is not responsible for the effects of metabolic inhibition, and both the transmembrane voltage and direct coupling to substrate oxidation via plasma-membrane-bound enzymes must be considered as possible energy sources for amino acid active transport.     

END‐OF‐LIFE CARE IN THE 21st CENTURY: ADVANCE DIRECTIVES IN UNIVERSAL RIGHTS DISCOURSE

This article explores universal normative bases that could help to shape a workable legal construct that would facilitate a global use of advance directives. Although I believe that advance directives are of universal character, my primary aim in approaching this issue is to remain realistic. I will make three claims. First, I will argue that the principles of autonomy, dignity and informed consent, embodied in the Oviedo Convention and the UNESCO Declaration on Bioethics and Human Rights, could arguably be regarded as universal bases for the global use of advance directives. Second, I will demonstrate that, despite the apparent consensus of ethical authorities in support of their global use, it is unlikely, for the time being, that such consensus could lead to unqualified legal recognition of advance directives, because of different understandings of the nature of the international rules, meanings of autonomy and dignity which are context‐specific and culture‐specific, and existing imperfections that make advance directives either unworkable or hardly applicable in practice. The third claim suggests that the fact that the concept of the advance directive is not universally shared does not mean that it should not become so, but never as the only option in managing incompetent patients. A way to proceed is to prioritize work on developing higher standards in managing incompetent patients and on progressing towards the realization of universal human rights in the sphere of bioethics, by advocating a universal, legally binding international convention that would outlaw human rights violations in end‐of‐life decision‐making.     

Crayfish,catfish and snails: the perils of uncontrolled biological control

A recent proposal that the Australian redclaw crayfish Cherax quadricarinatus and hybrid catfish could potentially control the snail hosts of schistosomiasis has been criticised on the grounds that crayfish pose a severe threat to aquatic ecosystems into which it might be introduced. This note examines the issue further, pointing out that both lack the host-specificity requirement to be a successful biological control agent. The catfish Clarias gariepinus is an omnivore and snails form only a small proportion of its diet; there is no evidence to suggest that it controls snail populations anywhere in Africa. The same applies to other species that have been proposed as biological control agents. Simple laboratory experiments are not an adequate guide to the efficiency of an animal as a biological control agent and detailed ecological investigations would usually demonstrate that few African fish species have this capability.