Onset of sexual maturity and relative growth of the freshwater crab Trichodactylus fluviatilis (Trichodactyloidea) in south-eastern Brazil

The main purpose of this study was to provide an estimate for the onset of morphological sexual maturity in the freshwater crab Trichodactylus fluviatilis, from a population located in south-eastern Brazil, based on the relative growth relationships, as well as the characterization of ''handedness''. Monthly collections were carried out at night, from January 2006 to January 2007, in a small water body. In the laboratory, the crabs were sexed; the following body structures were measured and the estimate of onset of sexual maturity was given by the logistic function, as y a/(1\+becx), for 50% of the population to reach the adult phase (CW50carapace width). Right propodus length and abdomen width were the best-fit relationships to represent the onset of sexual maturity for males and females, respectively. Based on the logistic function, the onset of sexual maturity was estimated to occur at around 18mm CW for both sexes. The relative growth recorded for this species is consistent with the model for brachyuran crabs (Hartnoll RG. 1982, Growth. In: Bliss, DE, editor. The biology of Crustacea: embryology, morphology and genetics. New York: Academic Press. p. 111-196), except for the abdomen growth, which is likely to be an adaptive condition related to protection of the newly hatched young. © 2013 Taylor & Francis.

Performance of Down syndrome subjects during a coincident timing task

Background: The time synchronization is a very important ability for the acquisition and performance of motor skills that generate the need to adapt the actions of body segments to external events of the environment that are changing their position in space. Down Syndrome (DS) individuals may present some deficits to perform tasks with synchronization demand. We aimed to investigate the performance of individuals with DS in a simple Coincident Timing task. Method. 32 individuals were divided into 2 groups: the Down syndrome group (DSG) comprised of 16 individuals with average age of 20 (+/- 5 years old), and a control group (CG) comprised of 16 individuals of the same age. All individuals performed the Simple Timing (ST) task and their performance was measured in milliseconds. The study was conducted in a single phase with the execution of 20 consecutive trials for each participant. Results: There was a significant difference in the intergroup analysis for the accuracy adjustment - Absolute Error (Z = 3.656, p = 0.001); and for the performance consistence - Variable Error (Z = 2.939, p = 0.003). Conclusion: DS individuals have more difficulty in integrating the motor action to an external stimulus and they also present more inconsistence in performance. Both groups presented the same tendency to delay their motor responses. © 2013 Torriani-Pasin et al.; licensee BioMed Central Ltd.

Relative growth and reproduction in Achelous spinicarpus (Crustacea: Portunidae) on the south-eastern continental shelf of Brazil

This investigation aimed to study the relative growth, morphological sexual maturity and fecundity of the swimming crab Achelous spinicarpus in a tropical region, on the south-eastern continental shelf of Brazil (25°S). Biometry of all specimens was conducted, including measurements of the cephalothorax, cheliped, abdomen and gonopods. Relative growth was described based on the equation for allometry (y = axb), and size at sexual maturity was determined from inflections in relations involving the cheliped, gonopods (males), and abdomen (females), as dependent variables, related to the cephalothorax width (independent variable). Fecundity was estimated by the gravimetric method. The relations of the length of the chelar propodus and carpal spine to the carapace width without the lateral spines (CW) showed positive allometry in both sexes, with a significant variation in the constant 'b' for males between the developmental stages (juvenile and adult) and the size at maturity estimated at 37 mm CW. In females, the abdomen was most appropriate for the estimate of morphological maturity, which occurred at a smaller size (32 mm CW), with a change in the growth pattern between the stages, passing from isometric (juveniles) to positive allometric (adults). The gonopods also showed different growth rates between developmental stages, in synchrony with the variables of the cheliped. Mean fecundity for the species was 53,984 eggs, with a positive correlation between the number of eggs exteriorized and the size of the female; the equations allowed interconversion between these variables, due to the adjustment of the power function (r2 ≥ 86%). © 2012 Marine Biological Association of the United Kingdom.

Comparison of body size, relative growth and size at onset sexual maturity of Uca uruguayensis (Crustacea: Decapoda: Ocypodidae) from different latitudes in the south-western Atlantic

Some crustaceans show variations of their reproductive biology within their geographical distribution, and knowledge about such variations is important for the comprehension of their reproductive adaptations. This study compared two populations of the fiddler crab Uca uruguayensis from two locations on the south-western Atlantic coast: Ubatuba Bay, São Paulo, Brazil and Samborombón Bay, Buenos Aires, Argentina. The population features analysed were the body size variation (carapace width = CW) and the size at the onset of sexual maturity (SOM) in order to test the hypothesis that the size at SOM, should be the same in relative terms (RSOM), independently of the latitudinal position. In the Brazilian population the CW ranged from 4.18 to 11.60 mm for males and 3.90 to 9.80 mm for females, and in the Argentinean population from 3.60 to 14.10 mm for males and 2.85 to 12.00 mm for females. In the Brazilian population the SOM was 7.1 (RSOM = 0.58) and 5.9 mm CW (RSOM = 0.57) for males and females, respectively, and in the Argentinean population it was 7.0 (RSOM = 0.42) and 6.75 mm CW (RSOM = 0.53) for males and females, respectively. This fact is probably related to a great plasticity in the life history features of Uca uruguayensis under different environmental conditions. © 2012 Marine Biological Association of the United Kingdom.

Effect of intercropping on yields of corn with different relative maturities and Palisadegrass

Intercropping corn (Zea mays L.) with palisadegrass [Brachiaria brizantha (Hochst. ex A. Rich) Stapf] can result in high amounts of residue and improve nutrient cycling. Long-season corn hybrids will live longer, competing with palisadegrass, which may reduce both corn and forage biomass yields. This study, conducted in the state of São Paulo, Brazil, had the objective of evaluating nutrient concentration and yield of corn hybrids with different maturity ratings as affected by intercropped palisadegrass as well as forage dry matter production. Te experimental design was randomized blocks with a factorial arrangement of eight treatments consisting of two cropping systems (corn alone and intercropped with palisadegrass) and four corn hybrids (105-, 121-, 132, and 144-d relative maturity). Compared with corn grown alone, intercropping treatments resulted in corn grain yields of 107% (105-d hybrid) to 71.7% (144-d hybrid). In the corn-alone system, the 132- and 144-d corn hybrids provided the highest corn yields (9581 and 9606 kg ha-1, respectively). Corn yield was similar between the single-crop and intercrop systems when using 105-, 121-, and 132-d hybrids. Intercropping with the 144-d hybrid reduced forage production (6619 kg ha-1) and quality of palisadegrass (86 g kg-1 of crude protein) compared with the other hybrids. Te intercropping system with the 132-d hybrid allowed both the highest corn grain (8860 kg ha-1) and palisadegrass (8256 kg ha-1) yields. Therefore, intercropping palisadegrass with the earlier (105-, 121-, and 132-d) corn hybrids is a viable option for crop-livestock integration because it did not affect either corn or palisadegrass yield. © 2013 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved.

Timing of prostaglandin F2α treatment in an estrogen-based protocol for timed artificial insemination or timed embryo transfer in lactating dairy cows

Objectives were to investigate progesterone concentrations and fertility comparing 2 different intervals from PGF2α treatment and induced ovulation in an estrogen-based ovulation synchronization protocol for timed artificial insemination (TAI) or timed embryo transfer (TET) in lactating dairy cows. A total of 1,058 lactating Holstein cows [primiparous (n=371) and multiparous (n=687)], yielding 34.1±0.33 kg of milk/d at various days in milk were randomly assigned to receive treatment with PGF2α on either d 7 or 8 of the following protocol: d 0: 2mg of estradiol benzoate + controlled internal drug release device; d 8: controlled internal drug release device removal + 1.0mg of estradiol cypionate; d 10: TAI or d 17: TET. Only cows with a corpus luteum at d 17 received an embryo and all cows received GnRH at TET. Pregnancy diagnoses were performed by detection (transrectal ultrasonography) of an embryo on d 28 or a fetus on d 60. Fertility [pregnancy per artificial insemination (P/AI) or pregnancy per embryo transfer (P/ET)] was affected by breeding technique (AI vs. ET) and time of PGF2α treatment (d 7 vs. 8) at the 28-d pregnancy diagnosis for TAI [32.9% (238) vs. 20.6% (168)] and TET cows [47% (243) vs. 40.7% (244)] and at the 60-d pregnancy diagnosis for TAI [30% (238) vs. 19.2% (168)] and TET cows [37.9% (243) vs. 33.5% (244)]. The progesterone (P4) concentration at d 10 altered fertility in TAI cows, with higher P/AI in cows with P4 concentration <0.1 ng/mL compared with cows with P4 concentration ≥0.1 ng/mL, and in ET cows, with higher P/ET in cows with P4 concentration <0.22 ng/mL compared with cows with P4 concentration ≥0.22 ng/mL. Prostaglandin F2α treatment at d 7 increased the percentage of cows with P4 <0.1 ng/mL on d 10 [39.4 (85) vs. 23.2 (54)]. Reducing the period between PGF2α and TAI from 72 to 48h in dairy cows resulted in a clear reduction in fertility in cows bred by TAI and a subtle negative effect in cows that received TET. The earlier PGF2α treatment benefits are most likely mediated through gamete transport, fertilization, or early embryo development and a more subtle effect of earlier PGF2α treatment that may be mediated through changes in the uterine or hormonal environment that manifests itself after ET on d 7. © 2013 American Dairy Science Association.

Relative growth, sexual maturity, and breeding season of three species of the genus Persephona (Decapoda: Brachyura: Leucosiidae): A comparative study

The relative growths of Persephona lichtensteinii, P. mediterranea, and P. punctata were investigated on the south-eastern Brazilian coast, focusing on differences in the growth rates between immature and mature phases, the onset of morphological sexual maturity, and the breeding seasons of these species. Crabs were collected every two months from January 1991 through to November 1992, from a shrimp fishing boat equipped with two otter-trawl nets. Significant differences in the patterns of body growth were observed between immature and mature phases of all three species. Changes in the growth rates of the chelipeds (males) and abdomen (females) observed for P. lichtensteinii, P. mediterranea, and P. punctata, seem to be related to the puberty moult for both sexes. Males of P. mediterranea and P. punctata reached larger mean sizes of carapace width than females, whereas no difference was recorded for P. lichtensteinii. The body size at which 50% of males attained sexual maturity was also larger in P. mediterranea and P. punctata, and smaller in P. lichtensteinii. The absence of a pronounced sexual dimorphism and the size at the onset of sexual maturity observed only for P. lichtensteinii might be explained by distinct reproductive strategies of males. The presence of ovigerous females during the entire sampling period suggests that all three species have a continuous reproduction pattern at the Ubatuba region. Future studies on the population structure, functional maturity, and mating system should improve the understanding of factors driving the biology and ecology of these species at a subtropical region. © Marine Biological Association of the United Kingdom 2013.

Nutritional status of the potted chrysanthemum relative to electrical conductivity and salt leaching

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Cover crop termination timing on rice crop production in a no-till system

Measuring shikimic acid accumulation in response to glyphosate applications can be a rapid and accurate way to quantify and predict glyphosate-induced damage to sensitive plants. The objective of this paper was to evaluate the effect of cover crop termination timing by glyphosate application on rice (Oryza sativa L.) yield in a no-till system. A factorial experiment, arranged in a split-plot design, was conducted for 2 yr. Treatments consisted of cover crops (main plots) and timed herbicide applications (subplots) to these cover crops (30, 20, 10, and 0 d before rice planting). There was a decrease in rice yield from 2866 kg ha-1 to 2322 kg ha-1 when the herbicide was applied closer to the rice planting day. Glyphosate application on cover crops increased shikimate concentrations in rice seedlings cultivated under palisade grass (Brachiaria brizantha), signal grass (B. ruziziensis), guinea grass (Panicum maximum), and weedy fallow (spontaneous vegetation) but not under millet (Pennisetum glaucum), which behaved similarly to the control (clean fallow, no glyphosate application). Glyphosate applications in the timing intervals used were associated with stress in the rice plants, and this association increased if cover crops took longer to completely dry and if higher amounts of biomass were produced. Millet, as a cover crop, allowed the highest seedling dry matter for upland rice and the highest rice yield. Our results suggest that using millet as a cover crop, with glyphosate application far from upland rice planting day (10 d or more), was the best option for upland rice under a no-tillage system. © Crop Science Society of America.