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PubMed1987

New method of evaluating sperm morphology with predictive value for human in vitro fertilization.

A prospective study was planned to evaluate sperm morphology as a parameter to predict the fertilization outcome in an in vitro fertilization program. Couples applying to in vitro fertilization were admitted into this project when the sperm concentration was greater than 20 million per mL and motility greater than 30 per cent. Based on new strict criteria for evaluating normal sperm morphology, patients were divided prospectively into 2 groups. In group I (25 patients) normal sperm morphology was less than 14 per cent, and in group II (71 patients) normal sperm morphology was greater than 14 per cent, using a threshold established previously. Multiple regression analysis was used to evaluate different parameters: concentration, motility, and morphology against the dependent variables, fertilization, and cleavage. The only factor which was significantly correlated with fertilization and cleavage was normal sperm morphology (P less than 0.0001). The fertilization rate (per oocyte) and the cleavage rate were 49.4 per cent and 47.6 per cent in group I and 88.3 per cent and 87 per cent in group II (P less than 0.0001). The ongoing pregnancy rate per laparoscopy and per embryo transfer was 4 per cent and 5.5 per cent, respectively, in group I and 18.3 per cent and 18.5 per cent, respectively, in group II (no significant difference). This study demonstrates the value of analyzing sperm morphology using the criteria recommended in terms of predicting fertilization and perhaps pregnancy outcome. Patients can be better counseled and the probability of fertilization or no fertilization can be more accurately established. Furthermore a trend is shown in the pregnancy rate that may indicate the importance of the male genome in establishing a pregnancy.

Embryo Transfer↗
PubMed2005

Age effect of broiler breeders on fertility and sperm penetration of the perivitelline layer of the ovum.

The objective of this study was to determine the age effect of a broiler breeder flock on duration of fertility and number of spermatozoa penetrating the perivitelline layer overlying the germinal disc (SP/mm(2) GDIPVL). Moreover, in the second half of the flock's reproductive life, the effect of using ejaculates of young roosters (CA2) in artificial insemination (AI) on the above parameters of fertility was estimated. The commercial flock of broiler breeder hens (n = 100) was inseminated six times from 31 to 62 weeks of age. Additional inseminations, with ejaculates of roosters aged 31 and 36 weeks (CA2), were performed at 56 and 62 weeks of age. AI was performed during two consecutive days (D0 and D1) with an insemination dose of 125 x 10(6) spermatozoa/0.06 ml containing pooled ejaculates. The following parameters were studied: the effective and maximum duration of fertility (De and Dm), percent of fertility on different days after AI (FD10, FD15 and FD20), indices of duration of sperm penetration (DSP, SP < or = 3/GDIPVL), SP/mm(2) GDIPVL in eggs laid on successive days after insemination of hens at different age, and correlations between some fertility indices. Both for De and Dm, the highest values were noted after AI of the layers at 36 weeks of age (14.8 +/- 0.49 and 17.4 +/- 0.46 days, respectively), which were about 2 days longer than at 56 weeks. All fertility indices decreased gradually with age, starting from AI at peak egg production (31-36 weeks of age), while the use of ejaculates from CA2 did not help to increase them significantly. Correlation coefficients between SP/mm(2) GDIPVL and the other fertility indices were positive and highest for eggs laid on D3. It is concluded that high De values can be obtained from broiler breeders in adequate environmental and technological conditions of AI. It is suggested that the age-related decrease in fertility is more pronounced in females, in which the efficiency of sperm storage tubules decreases. The present fertility indices indicate the possibility of lengthening AI intervals, especially at peak egg production.

Aging↗
PubMed2005

Environmental effects on progesterone profile measures of dairy cow fertility.

Environmental effects on fertility measures early in lactation, such as the interval from calving to first luteal activity (CLA), proportion of samples with luteal activity during the first 60 days after calving (PLA) and interval to first ovulatory oestrus (OOE) were studied. In addition, traditional measurements of fertility, such as pregnancy to first insemination, number of inseminations per service period and interval from first to last insemination were studied as well as associations between the early and late measurements. Data were collected from an experimental herd during 15 years and included 1106 post-partum periods from 191 Swedish Holsteins and 325 Swedish Red and White dairy cows. Individual milk progesterone samples were taken twice a week until cyclicity and thereafter less frequently. First parity cows had 14.8 and 18.1 days longer CLA (LS-means difference) than second parity cows and older cows, respectively. Moreover, CLA was 10.5 days longer for cows that calved during the winter season compared with the summer season and 7.5 days longer for cows in tie-stalls than cows in loose-housing system. Cows treated for mastitis and lameness had 8.4 and 18.0 days longer CLA, respectively, compared with healthy cows. OOE was affected in the same way as CLA by the different environmental factors. PLA was a good indicator of CLA, and there was a high correlation (-0.69) between these two measurements. Treatment for lameness had a significant influence on all late fertility measurements, whereas housing was significant only for pregnancy to first insemination. All fertility traits were unfavourably associated with increased milk production. Regression of late fertility measurements on early fertility measurements had only a minor association with conception at first AI and interval from first to last AI for cows with conventional calving intervals, i.e. a 22 days later, CLA increased the interval from first to last insemination by 3.4 days. Early measurements had repeatabilities of 0.14-0.16, indicating a higher influence by the cow itself compared with late measurements, which had repeatabilities of 0.09-0.10. Our study shows that early fertility measurements have a possibility to be used in breeding for better fertility. To improve the early fertility of the cow, there are a number of important factors that have to be taken into account.

Animals↗
PubMed2005

Effects of copper on the fertilization success of the soft coral Lobophytum compactum.

This study provides the first information on the effects of various concentrations of copper on the fertilization success of gametes from the soft coral Lobophytum compactum. Two experiments were conducted to determine the effect of copper on fertilization success during the mass coral spawning in 2004 on the Great Barrier Reef (GBR). The results from the first experiment showed a surprising resistance to copper with control treatments showing 90% fertilization compared to 65% fertilization in measured copper concentrations up to 132 microg/L. Copper concentrations of 69 microg/L and higher resulted in significantly reduced fertilization success when compared to the controls. Copper doses were increased in experiment 2 and the EC50 value for copper effects on fertilization success was 261 microg/L (208-328 microg/L, 95% confidence limits). In this follow-up experiment, fertilization success was significantly lower than the controls after exposure to copper concentrations of 117 microg/L and above. The EC50 value reported here is much higher than those found in the literature on fertilization experiments conducted on hard coral gametes and also for the fertilization success of other marine organisms, including sea urchins, oysters and fish.

Animals↗
PubMed2006

Leaching potential of heavy metals (Cd, Ni, Pb, Cu and Zn) from acidic sandy soil amended with dolomite phosphate rock (DPR) fertilizers.

There is an increasing concern on heavy metal leaching from the soils amended with sewage sludge. A column study was conducted to examine the extent of leaching of five important heavy metals (Cd, Ni, Pb, Cu and Zn) from an acidic sandy soil amended with different dolomite phosphate rock (DPR) fertilizers (an application rate of 1% fertilizers) developed from DPR and N-Viro (consisting of biosolids and fly ash) at 0%, 10%, 20%, 30%, 40%, 50% and 100% DPR. Ten leaching events were carried out with each event done at an interval of 7 days and with total leaching volume of 1183mm, which is equivalent to the mean annual rainfall of this region during the period of 2001-2003. Leachate was collected after each leaching event and analyzed for heavy metals. The maximum leachate concentrations of Cd, Ni, Pb, Cu and Zn were all below drinking water quality guidance limits set by Florida Department of Environmental Protection and World Health Organization, suggesting that the application of DPR fertilizers may not pose a threat to water quality by leaching. Most of leachate concentrations of Cd, Ni and Pb were below their detection limits and there were no significant differences between the control and the treatments with different DPR fertilizers. By contrast, there were higher leachate concentrations of Cu and Zn (ranging from 0.7 to 37.1mug Cu/l and 5.1 to 205.6mug Zn/l for all treatments) due to their higher contents in both the soil and different DPR fertilizers compared with Cd, Ni and Pb. The leachate concentrations of Cu and Zn for each treatment decreased with increasing leaching events. The differences in leachate concentrations of Cu and Zn between the control and the treatments with different DPR fertilizers containing N-Viro were significant, especially in the first several leaching events and, moreover, they increased with increasing proportion of N-Viro in the DPR fertilizers. There were similar trends in total losses of Cu and Zn after ten leaching events. Greater differences in both leachate concentrations and total losses of Zn between the control and the treatments containing N-Viro were noted. Total losses of Zn for the treatments containing N-Viro were 3.0-5.1 times higher than those for the control compared with 1.4-2.2 times higher for total losses of Cu, suggesting that greater proportions of Zn losses came from the DPR fertilizers due to the greater mobility of Zn in the DPR fertilizers compared with Cu.

Fertilizers↗
PubMed1992

Fertilization, cleavage, and cytogenetics of 48-hour zona-intact and zona-free human unfertilized oocytes reinseminated with donor sperm.

OBJECTIVE: To examine the fertilization rates of 48-hour unfertilized oocytes inseminated with fertile donor sperm and to evaluate the cleavage and cytogenetics of ensuing embryos. DESIGN: Prospective. SETTING: Assisted reproductive technology (ART) program. PATIENTS: Four hundred ninety-seven unfertilized oocytes from 97 ART patients were categorized into four groups. A (zona-intact) and B (zona-free) were from patients with partial fertilization failure, whereas C (zona-intact) and D (zona-free) were total fertilization failures. RESULTS: Fertilization rates in groups A and B were significantly higher than C and D (33.2% to 60.9% versus 20.0% to 48.1%; P less than 0.01). Zona-free oocytes had higher fertilization rates than zona-intact oocytes (48.1% to 60.9% versus 20.0% to 32.2%). Multiple pronuclei were high in zona-free oocytes (33.1% to 41.3%). Forty-eight to 54% of embryos generated after donor insemination had chromosome anomalies (mosaicism, aneuploidy, pulverization). CONCLUSIONS: One cause of total fertilization failure appears to lie in intrinsic oocyte problems confined to the zona and oolemma. The fertilization of 48-hour unfertilized oocytes may be of some value in diagnosing fertilization failure in ART patients.

Cell Division↗
PubMed1993

Prediction of in vitro fertilization rates from semen variables.

OBJECTIVE: To assess the value of semen variables for predicting fertilization rates. DESIGN: Measures of the fresh semen and the motile sperm fraction used for insemination were related to the fertilization rate by multiple regression analysis. The regression model was then used to construct a two-dimensional clinical chart. SETTING: University-affiliated reproductive medicine unit. PATIENTS: The results of 294 IVF cycles were analyzed retrospectively. Selection criteria were: [1] first cycle of IVF; [2] tubal and/or male factor infertility; and [3] four or more oocytes inseminated. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The fertilization rate was related to measured variables of the fresh semen and the motile sperm fraction used for insemination. Fertilization rate was categorized as poor (< 35%) or acceptable (> or = 35%). RESULTS: Multiple regression analysis demonstrated a strong correlation between the fertilization rate and the combined indexes of percentage normal morphology and grade of motility in the fresh semen and percentage progressive motility in the motile sperm fraction. A two-dimensional chart that expressed these relationships was constructed. Its accuracy of prediction was 77% for poor fertilization and 95% for acceptable fertilization. CONCLUSIONS: The fertilization rate is strongly correlated with percentage normal sperm morphology in the fresh semen and the percentage progressive motility in the motile sperm fraction used for insemination. The clinical chart provides a simple but powerful tool for predicting fertilization outcome.

Confidence Intervals↗
PubMed1994

Utility of in vitro fertilization at diagnostic laparoscopy.

OBJECTIVE: To compare stimulation and outcome variables for IVF in stimulated cycles when ova are retrieved during diagnostic infertility laparoscopy versus transvaginal ultrasound (US) directed retrieval and to investigate the presence of unexpected failed fertilization in the diagnostic laparoscopy group, which allows an opportunity to diagnosis an etiology of infertility based on gamete interaction. DESIGN: Consecutive patients who needed infertility diagnostic laparoscopy and agreed to combination with IVF were compared with concurrent patients undergoing transvaginal US IVF. Male factor screening parameters (semen analysis, sperm penetrating assay) and resultant fertilization were analyzed for these patients. SETTING: The George Washington University Hospital, a tertiary referral center offering assisted reproductive technologies. Patients for diagnostic laparoscopy combined with IVF were enrolled in the Program of Oocyte Retrieval at Diagnostic Laparoscopy (PORDL). PARTICIPANTS: One hundred twenty-four women enrolled for diagnostic laparoscopy combined with IVF; 237 women were concurrently enrolled for transvaginal US IVF. RESULTS: Response variables (number of follicles, days of monitoring, ampules of hMG, maximum E2) between the two groups were similar. Outcome variables (ova retrieved, ova fertilized, ova cleaved, clinical pregnancy rate per embryo transferred) were similar despite a significantly higher number of embryos transferred for the transvaginal US group. The clinical pregnancy rate per cycle was similar, 26% versus 28% for the women in the transvaginal US versus those women in the PORDL group, as was the clinical pregnancy rate per ET, 31% versus 34%, respectively. The number of fertilized ova for each group was not significantly different: 5.5 +/- 0.3 for the transvaginal group versus 4.8 +/- 0.4 for the PORDL group. Patients in the PORDL group with a known male factor (group B) had a lower fertilization rate than those with no male factor (group A). Within the group A with no detectable male factor prospectively, 17.2% had unexpectedly poor fertilization (group A1), whereas the rest of the group A patients had higher fertilization rates as was expected (group A2). The clinical pregnancy rate per ET for group A1 was 0% compared with 43.4% for the group A2 patients. CONCLUSIONS: In vitro fertilization can be successfully performed during diagnostic laparoscopy yielding comparable results to transvaginal ultrasound IVF while gaining diagnostic information concerning sperm-ova interaction (i.e., fertilization).

Adult↗
PubMed1995

Impact of immunoglobulin isotype and sperm surface location of antisperm antibodies on fertilization in vitro in the human.

OBJECTIVE: To investigate the impact of immunoglobulin (Ig) isotypes and their location on the human sperm surface on fertilization in vitro. DESIGN: Restrospective review and analysis. SETTING: Reproductive endocrine division of a level 3 academic center. PATIENTS: Forty-eight couples (80 IVF cycles) with males showing positive antisperm antibodies on the sperm surface by immunobead test, treated by IVF at the Norfolk Program. MAIN OUTCOME MEASURE: Evaluation of total fertilization rate of preovulatory oocytes (metaphase II-metaphase I). RESULTS: Immunoglobulin G and IgA antibody levels have no significant correlation with total fertilization rate of preovulatory oocytes by logistic regression. Immunoglobulin M, present in 44% of the couples, had a strong correlation with fertilization. When IgA showed very high levels of binding (> 68%) and IgM binding was > 40%, the fertilization rate dropped significantly. A strong correlation between presence of antibodies and fertilization rate was seen when IgM was directed to the head or tail tip of the sperm. Immunoglobulin A induced a statistically significant reduction of fertilization only when it was present on the head. CONCLUSION: Two male antisperm Ig isotypes significantly impaired fertilization rates. Immunoglobulin A exerted its impact only when high level of binding was detected on the head. Immunoglobulin M, present in 44% of the males, was the Ig isotype that most significantly affected fertilization rates when localized both at the head and at the tail tip level.

Autoantibodies↗
PubMed1987

Fertilization and cleavage rates of heparin-exposed human oocytes in vitro, and the effect of heparin on the acrosome reaction.

Fertilization and cleavage rates were compared in 1024 heparin-exposed and nonexposed human oocytes recovered from 183 consecutive in vitro fertilization (IVF) cycles. Heparinized Ham's F-10 medium, (Gibco, Grand Island, NY) 1.0 ml (2.0 mg heparin/ml) was added to bloody follicular fluid; clear follicular aspirates did not receive heparin. Fertilization and cleavage rates for heparin-exposed (n = 714) and nonexposed (n = 310) oocytes were not significantly different: 63.9 versus 61.6% fertilized (chi 2 = 0.472); 89.3 versus 87.4% of fertilized eggs cleaved (chi 2 = 0.445). A subset of 100 patients, each contributing both heparin-exposed and nonexposed oocytes, also was evaluated. Fertilization and cleavage rates were not significantly different: 59.1 versus 60.8% fertilized (chi 2 = 0.192); 87.6 versus 87.2% of fertilized oocytes cleaved (chi 2 = 0.014). A modified triple stain was used to evaluate the acrosome reaction rate of sperm that had been coincubated with 76 oocytes from ten patients. There was no significant difference in the proportion of viable acrosome-reacted sperm following incubation with heparin-exposed (1.9 +/- 1.0%) versus nonexposed (2.3 +/- 1.2%) (mean +/- standard deviation [SD]) oocytes. The addition of heparin to follicular fluid at the time of oocyte recovery for IVF has no apparent effect on fertilization or cleavage in vitro, nor any influence on the acrosome reaction.

Acrosome↗
PubMed1999

Electrical activation and in vitro development of human oocytes that fail to fertilize after intracytoplasmic sperm injection.

OBJECTIVE: To determine whether electrically stimulated Ca2+ influx can "rescue" fertilization and early embryogenesis in human oocytes that fail to fertilize after intracytoplasmic sperm injection (ICSI). DESIGN: Prospective, randomized trial of a laboratory procedure. SETTING: A research laboratory at a university medical center. PATIENT(S): Discarded oocytes from ICSI-IVF cycles. INTERVENTION(S): Oocytes (n = 104) that showed no evidence of fertilization 16-24 hours after ICSI were assigned to three treatment groups: group 1 (one direct current electrical pulse at 1.36-1.50 kV/cm for 40-60 micros), group 2 (three pulses every 15-20 minutes), or group 3 (treated the same as group 2 but with no electrical stimulation). MAIN OUTCOME MEASURE(S): After stimulation, the oocytes were cultured in vitro for 3-5 days. Oocytes that displayed two pronuclei and a second polar body within 16 hours were considered to have fertilized normally. Fertilization and embryo cleavage rates were compared between groups. RESULT(S): Fertilization occurred in 26 (70%) of 37 and 38 (78%) of 49 group 1 and 2 oocytes, respectively, but in only 5 (27%) of 18 group 3 oocytes. Within 3 days, group 2 embryos routinely developed beyond the two-cell to four-cell stage (61% versus 13% in group 1); 11% of these oocytes developed to the morula or early blastocyst stage. Sex chromosome analyses indicated 10 male and 8 female embryos. CONCLUSION(S): Oocytes that fail to fertilize by 24 hours after ICSI can resume apparently normal fertilization and early embryonic development in response to electrical stimulation. Moreover, the degree of cytoplasmic activation as determined by the number of pulses applied affects fertilization efficiency and early embryonic development.

Adult↗
PubMed1982

In vitro fertilization rates after varicocele repair.

Causal relationship of varicocele to infertility is controversial. Studies of hormonal milieu, semen and testicular tissue yield data of debatable significance. We herein assay the fertilizing ability of men with varicocele and monitor changes consequent to surgical correction of varicocele. Zona-free hamster ova were used to determine fertilizing ability. A fertilization rate of less than 10 per cent correlates with infertility. Between May 1978 and November 1979, 75 men with varicocele presenting for fertility evaluation and 23 men with painful varicocele were tested. Of the patients infertile clinically and by in vitro fertilization assay 42 elected ligation of the internal spermatic vein(s). Average fertilization rate of the painful varicocele group was 20.5 per cent and for the infertile group it was 1.2 per cent. Average fertilization rates postoperatively in the infertile group were 2.9 per cent (3 months), 7.7 per cent (6 months), 2.8 per cent (9 months), 7.8 per cent (12 months), 17.5 per cent (15 months) and 8.0 per cent (18 months). Pregnancies occurred only in partners of men whose fertilization rates were between 2.9 and 8.3 per cent preoperatively and who improved to greater than 10 per cent postoperatively. The in vitro fertilization assay may help select those individuals with varicocele and infertility most likely to benefit from varicocele repair.

Fertilization in Vitro↗
PubMed2000

Identification of embryo paternity using polymorphic DNA markers to assess fertilizing capacity of spermatozoa after heterospermic insemination in boars.

Differences in sperm fertilizing capacity of males often remain undetected by routine semen parameters. Heterospermic insemination with equal numbers of spermatozoa from 2 males is an accurate method for assessing differences in fertility. Use of heterospermic insemination depends on a reliable, efficient assay to identify paternity of conceptuses or offspring. In this study, polymorphic DNA markers amplified by PCR were tested to determine paternity of Day 5 to 6 embryos. The fertilizing capacity of 2 boars (A and B) with similar semen parameters was compared after homospermic (n=14 gilts) and heterospermic (n=11 gilts) insemination. Single AI's were performed under suboptimal conditions using 1 x 10(9) spermatozoa at 12 to 24 h before ovulation to prompt differences in fertilization and to stimulate sperm competition. The fertilization rate and the number of accessory spermatozoa were determined in Day 5 to 6 embryos. Using 5 different polymorphic DNA markers, paternity could be determined in 95.8% of the embryos. Boar B sired significantly (P<0.05) more offspring than Boar A after insemination with pooled semen, and this was reflected by a significantly (P<0.05) higher number of accessory spermatozoa following homospermic insemination with semen from Boar B, although fertilization rates did not differ between the 2 boars after homospermic insemination. The results suggest that the viability of spermatozoa in the female reproductive tract contributes to differences in fertility rates of males with similar in vitro sperm quality parameters. The number of accessory spermatozoa is a more sensitive measure of boar fertility than the fertilization rate. Polymorphic DNA markers are suitable for verification of parentage even at a very early stage of embryonic development.

Animals↗
PubMedDate not supplied

In vitro fertilization rate of mouse eggs with sperm after X-irradiation at various spermatogenetic stages.

The frequency of in vitro fertilization of mouse eggs using sperm obtained weekly (for 1-9 weeks) from epididymis after testicular X-irradiation (200 rad) was observed. The sperm concentrations for insemination were 100, 200 and 300/mm3. The number of fertilized eggs seemed to remain constant almost at control level (90-98%) until the 4th week after X-irradiation. Thereafter, the number declined to reach a minimum level (about 30-50%) in the 6th week; they then recovered completely in the 8th week. This tendency was found at all sperm concentrations used. This result indicates that the most sensitive stage for the fertilization capacity of sperm to X-rays was the early spermatocytes or the late spermatogonia. The high radiosensitivity of the fertilization capacity of sperm irradiated during the early-spermatocyte to late-spermatogonial stage, corresponded well with the rate of induction of sperm abnormalities and spermatogenetic cell killing. The in vitro fertilization rate was not restored by an increase in sperm concentration at insemination; it is, therefore, likely that the in vitro fertilization frequency depends on the proportion of sperm with abnormal morphology and abnormal fertilization ability, and sperm number seems to have hardly any influence on the fertilization rate, as far as the in vitro fertilization experiment is concerned.

Animals↗
PubMed2003

Effect of organic and mineral fertilizers on N-use by wheat under different irrigation frequencies.

A field trial was established in Errachidia, southern Morocco, to investigate the interaction between wheat residue management and mineral 15N-labelled ammonium sulphate, under different irrigation treatments, applied to wheat (Triticum durum var. Karim). In treatments I1, I2, I3 and I4, plots were irrigated every 10, 15, 21 and 30 days. Each plot contained three sub-plots that received three fertilization treatments: T1 received 42 kg N ha-1 of ammonium sulphate before seedling, 42 kg N ha-1 of ammonium sulphate labelled with 9.764 at % 15N excess at tillering and 84 N kg ha-1 of ammonium sulphate at flowering; T2 received 42 kg N ha-1 of ammonium sulphate labelled with 9.764 at % 15N excess at seedling, 42 kg N ha-1 at tillering and 42 kg N ha-1 at flowering; T3 received 4800 kg ha-1 of wheat residue labelled with 1.504 at % 15N excess and 42 kg N ha-1 of ammonium sulphate before seedling and 42 kg N ha-1 of ammonium sulphate at flowering. Nitrogen fertilization with 168 kg N ha-1 did no significantly increase grain and straw yields in comparison to the 126 kg N ha-1 application. The combination of the organic input and supplementary application of mineral fertilizer N has been found as a more attractive management option. For all irrigation treatments, the % recovery of N in the whole plant was higher in plants that received 15N at tillering (63%, 49% respectively for irrigation intervals between 10 and 30 d) than in plants that received 15N just after seeding (28% for irrigation each 10- and 30-d intervals). For the irrigation treatment each 10 and 15 days, the 15N was mainly recovered by the grain for all fertilization treatments, whereas for irrigation treatment each 30 days, the grain and straw recovered nearly equal amounts of fertilizer. For grain and straw of wheat, nitrogen in the plant derived from the fertilizer was low, while most of the N was derived from the soil for all irrigation and fertilization treatments. The % nitrogen in the plant derived from the fertilizer values showed no significant difference between the different plant parts. The results suggested a dominant influence of moisture availability on the fertilizer N uptake by wheat. Under dry conditions the losses of N can be allotted to denitrification and volatilisation.

Agriculture↗
PubMed1991

Fertility and viability at the Sod locus in Drosophila melanogaster: non-additive and asymmetric selection.

Experiments were designed to test in Drosophila melanogaster the effect of mating type at the Sod locus on fertility and viability. The experiments show that fertility is neither additive (or multiplicative) nor symmetric, i.e. that the fertility of a mating type cannot be predicted from the average fertility of the two genotypes involved in the mating. There is no significant male x female interaction with respect or progeny viability; but the interaction is significant for productivity, i.e. when fertility and viability are jointly taken into account. There is overdominance with respect to female fertility, but not with respect to male fertility or to viability. There also is alloprocoptic selection with respect to fertility and with respect to productivity, i.e. mating between like homozygotes are less fertile and productive than matings between dissimilar homozygotes. Selection at the Sod locus yields stable polymorphic equilibria, with the frequency of the F allele predicted at P = 0.641 or 0.695, respectively for low and high larval density.

Animals↗
PubMed2004

Fertilizer characterization: isotopic data (N, S, O, C, and Sr).

A detailed isotopic characterization (delta15N(Ntotal), delta15N(NO3), delta18O(NO3), delta34S(SO4), delta18O(SO4), (delta13C(Ctotal), and 87Sr/86Sr) of 27 commercial fertilizers used in Spain is presented in this paper. Results together with a compilation of fertilizer isotopic published data are used for two purposes: (i) to identify the origin of the primary constituents and raw materials used in fertilizer manufacture and relate these data with their heavy metals and rare earth elements (REE) contents; (ii) to compare the fertilizer isotopic signatures with natural values and other anthropogenic pollutants and evaluate the usefulness of multi-isotopic analyses to trace fertilizer contaminations in future study cases. Isotope data permit us to know, in most cases, the origin of the primary constituents of fertilizers, and the 87Sr/86Sr ratio distinguishes the origin of the phosphate content--phosphorites or carbonatites--which in turn implies a qualitatively defined and potentially contaminant presence of REE and heavy metals in fertilizers. Delta15N, delta34S, and 87Sr/86Sr have already been used to trace fertilizer contaminations. Their utility can be improved by the coupled use of delta15N(NO3)-delta18O(NO3) and delta34S(SO4)-delta18O(SO4) to evaluate the fractionation processes that can affect contaminants. Moreover, multi-isotopic analyses, using heavy isotopes, allow us to see beyond the fractionation effects to the fertilizer stable isotope signatures and a better distinction from other anthropogenic contaminants.

Environmental Pollutants↗
PubMed2002

Use of polysulfone in controlled-release NPK fertilizer formulations.

Encapsulation of fertilizers in polymeric coatings is a method used to reduce fertilizer losses and to minimize environmental pollution. Polysulfone was used for a coating preparation for soluble NPK granular fertilizer in controlled-release fertilizer formulations. The coatings were formed by the phase inversion technique (wet method). The influence of the polymer concentration in the film-forming solution on the physical properties of the coatings was examined. The coating structure controls the diffusion of the elements from the interior of the fertilizer granule. It was experimentally confirmed that the use of polysulfone as a coating for a soluble fertilizer decreases the release rate of components. Moreover, the release rate of nutrients from coated granules decreases with the decrease of the coating porosity. In the case of coating with 38.5% porosity, prepared from 13.5% polymer solution after 5 h of test, 100% of NH(4)(+) was released, whereas only 19.0% of NH(4)(+) was released after 5 h for the coating with 11% porosity. In addition, coating of fertilizers leads to improvement of handling properties, and the crushing strength of all coated fertilizers was an average 40% higher than that for uncoated NPK fertilizer.

Chemical Phenomena↗