scholarly journals Internal incubation and early hatching in brood parasitic birds

2010 ◽  
Vol 278 (1708) ◽  
pp. 1019-1024 ◽  
Author(s):  
T. R. Birkhead ◽  
N. Hemmings ◽  
C. N. Spottiswoode ◽  
O. Mikulica ◽  
C. Moskát ◽  
...  
Keyword(s):  
Embryo Development ◽  
Zebra Finch ◽  
Brood Parasitism ◽  
Direct Consequence ◽  
Egg Mass ◽  
Advanced Stage ◽  
Cuculus Canorus ◽  
Specific Adaptation ◽  
Embryo Stage ◽  
The Difference

The offspring of brood parasitic birds benefit from hatching earlier than host young. A proposed but little-known strategy to achieve this is ‘internal incubation’, by retaining the egg in the oviduct for an additional 24 h. To test this, we quantified the stage of embryo development at laying in four brood parasitic birds (European cuckoo, Cuculus canorus ; African cuckoo, Cuculus gularis ; greater honeyguide, Indicator indicator ; and the cuckoo finch, Anomalospiza imberbis ). For the two cuckoos and the honeyguide, all of which lay at 48 h intervals, embryos were at a relatively advanced stage at laying; but for the cuckoo finch (laying interval: 24 h) embryo stage was similar to all other passerines laying at 24 h intervals. The stage of embryo development in the two cuckoos and honeyguide was similar to that of a non-parasitic species that lay at an interval of 44–46 h, but also to the eggs of the zebra finch Taeniopygia guttata incubated artificially at body temperature immediately after laying, for a further 24 h. Comparison with the zebra finch shows that internal incubation in the two cuckoos and honeyguide advances hatching by 31 h, a figure consistent with the difference between the expected and the observed duration of incubation in the European cuckoo predicted from egg mass. Rather than being a specific adaptation to brood parasitism, internal incubation is a direct consequence of a protracted interval between ovulation (and fertilization) and laying, but because it results in early hatching may have predisposed certain species to become brood parasitic.

scholarly journals Effectiveness of riluzole in the treatment of amyotrophic lateral sclerosis

2021 ◽  
Author(s):  
Renato Puccioni Sohler ◽  
Gabriel Pinto Mendonça ◽  
Rodrigo Cesar Carvalho Freitas ◽  
José Roberto Ribas
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Survival Rate ◽  
Motor Neuron ◽  
Placebo Treatment ◽  
First Year ◽  
Advanced Stage ◽  
Mesh Terms ◽  
Student Test ◽  
The Difference ◽  
Lateral Sclerosis

Background: amyotrophic lateral sclerosis (ALS) is a motor neuron degenerative disease with high mortality and few therapies. One of these is riluzole, inspite of uncertainty effectiveness. Objective: the aim of this study was to evaluate the survival rate associated with the use of this medication in the treatment of ALS. Methods: The study was based on a narrative review of the scientific articles that used randomized controled trials with riluzole for ALS. We selected articles published in english during the period of January 1th, 2000 to December 31th, 2020. The MeSH terms “amyotrophic lateral sclerosis” or “motor neuron disease” and “riluzole” or “rilutek” were used in Pubmed and Lilacs databases. Studies that used only patients with advanced stage ALS were excluded. The t-Student test between sample means was applied to determine the significance of the difference between the survival time (years) of the riluzole and placebo treatment, for a 95% confidence level. Results: through the search, four articles were obtained (Table 1). Conclusion: Data analysis showed that riluzole is only effective in the first year. From the second onward, it does not exceed the results of the placebo.

scholarly journals Inhibition of DRP1 Impedes Zygotic Genome Activation and Preimplantation Development in Mice

2021 ◽  
Vol 9 ◽  
Author(s):  
Yuanyuan Li ◽  
Ning-Hua Mei ◽  
Gui-Ping Cheng ◽  
Jing Yang ◽  
Li-Quan Zhou
Keyword(s):  
Embryo Development ◽  
Preimplantation Embryo ◽  
Preimplantation Embryos ◽  
Dependent Manner ◽  
Zygotic Genome Activation ◽  
Preimplantation Embryo Development ◽  
Cell Embryo ◽  
Embryo Stage ◽  
Genome Activation ◽  
Zygotic Genome

Mitochondrion plays an indispensable role during preimplantation embryo development. Dynamic-related protein 1 (DRP1) is critical for mitochondrial fission and controls oocyte maturation. However, its role in preimplantation embryo development is still lacking. In this study, we demonstrate that inhibition of DRP1 activity by mitochondrial division inhibitor-1, a small molecule reported to specifically inhibit DRP1 activity, can cause severe developmental arrest of preimplantation embryos in a dose-dependent manner in mice. Meanwhile, DRP1 inhibition resulted in mitochondrial dysfunction including decreased mitochondrial activity, loss of mitochondrial membrane potential, reduced mitochondrial copy number and inadequate ATP by disrupting both expression and activity of DRP1 and mitochondrial complex assembly, leading to excessive ROS production, severe DNA damage and cell cycle arrest at 2-cell embryo stage. Furthermore, reduced transcriptional and translational activity and altered histone modifications in DRP1-inhibited embryos contributed to impeded zygotic genome activation, which prevented early embryos from efficient development beyond 2-cell embryo stage. These results show that DRP1 inhibition has potential cytotoxic effects on mammalian reproduction, and DRP1 inhibitor should be used with caution when it is applied to treat diseases. Additionally, this study improves our understanding of the crosstalk between mitochondrial metabolism and zygotic genome activation.

Billing Codes Determine Lower Physician Income for Primary Care and Non-Procedural Specialties

2019 ◽  
Vol 22 (2) ◽  
Author(s):  
Arielle L. Langer ◽  
Miriam Laugesen
Keyword(s):  
Primary Care ◽  
Family Medicine ◽  
Primary Care Physicians ◽  
Direct Consequence ◽  
Medical Specialties ◽  
Income Differences ◽  
Income Gap ◽  
Physician Income ◽  
The Difference ◽  
The Relationship

Abstract The income gap between specialists and primary care physicians and among specialists is well established, but the drivers of this difference are not well delineated. Using the Community Tracking Study (CTS) Physician Survey, we sought to isolate and compare premiums paid to physicians for specialization and the proportion of time spent on offices visit rather than procedures. We divided medical subspecialties according the proportion of Medicare billing for Evaluation and Management (E&M) codes for the specialty as a whole. We report substantial differences in income across physician specialty, and over 70 percent of the difference in income remained controlling for factors that may confound the relationship between income and specialty including gender, location and type of practice, and hours. We note a large variation in premiums for specialization: 11.3–46.8 percent above family medicine after controlling for confounders. Classifying medical subspecialties by E&M billing as procedural versus non-procedural specialties revealed clear income differences. Controlling for confounders, procedural medical specialties earned 37.5 percent more than family medicine, as compared with 15.3 percent for non-procedural medical specialties. This analysis suggests that differences in physician income and resulting incentives are a direct consequence of the payment structure itself, rather than compensation for additional years of training or a reflection of different underlying demographics.

10 Pregnancy rates following artificial insemination or embryo transfer in lactating Holstein cows

2020 ◽  
Vol 32 (2) ◽  
pp. 130
Author(s):  
M. Oliveira ◽  
R. Santos ◽  
R. Chebel ◽  
D. Demetrio
Keyword(s):  
Embryo Transfer ◽  
Embryo Development ◽  
Artificial Insemination ◽  
Early Embryo ◽  
Pregnancy Rates ◽  
Holstein Cows ◽  
Genetic Merit ◽  
Excessive Heat ◽  
The Difference ◽  
June July

Excessive heat affects the fertility of high production lactating cows, and reduced pregnancy rates (PR) are observed during summer and early fall. Embryo production programs are used to produce more calves from high genetic merit animals, but could it also increase fertility by bypassing all the negative variables affecting the embryo development before Day 7 (oocyte development, ovulation, fertilization, early embryo development)? The data from AIs and embryo transfers (ET) between June 2017 and May 2019 were analysed. June, July, August, September, and October were called critical months (first-service AI conception rate dropped below 44%). The cows were located at Maddox Dairy in Riverdale, CA, USA, a Holstein herd that milks 3500 cows with a 305-day mature-equivalent milk production of 12 800 kg. First- and second-lactation cows were enrolled in a Presynch-Ovsynch oestrus-synchronization program and scheduled for the first AI at 86 days after calving or to receive an embryo 7 or 8 days after the expected heat. The embryos were produced invivo or invitro from Holstein donors and were transferred fresh or frozen. Blood was sampled on Day 30 after expected heat day (23 days after embryo transfer), and pregnancy was detected by the IDEXX PAG Bovine Pregnancy Test. Table 1 summarises the results, where ET PR% is the number of pregnant cows divided by the number of cows that received and embryo. All the cows synchronized for AI were bred, but only cows with the presence of a corpus luteum (CL) on ET day received an embryo. The presence of a CL was not detected in 28.7% (471/1642) of the cows (32.2% in the critical months and 25.7% in the others). Unfortunately, we could not detect the presence of a CL by ultrasonography every time we transferred embryos, so the nonovulation rate might be overestimated. The cows without a CL were considered open and used to calculate the adjusted PR (AdjPR%). Embryo transfer PR is superior to that of AI, especially during the critical months. Fresh invivo embryos have the most impact. When the cows without CLs are considered open, the difference between AI and ET is still evident for fresh invivo embryos. Besides producing animals with higher genetic merit, depending on the type of embryo used, ET can increase fertility in lactating Holstein cows, especially during the critical months. The other benefit of using ET is that cows that do not ovulate are synchronized right away, which is not the case for AI cows. Table 1.AI×embryo transfer in lactating Holstein cows1 from June 2017 to May 20192 Item Critical months (June to October) Other months (November to May) All year %PR n Adj PR% n %PR n Adj PR% n %PR n Adj PR% n Artificial insemination 41.2% 896 41.2% 896 47.7% 1767 47.7% 1767 45.5% 2663 2663 Fresh invivo embryo 62.7% 373 47.5% 493 69.5% 262 55.3% 329 65.5% 635 50.6% 822 Frozen invivo embryo 59.3% 221 44.8% 292 59.4% 256 47.3% 322 59.3% 477 46.1% 614 IVF fresh embryo 47.9% 167 36.2% 221 54.0% 363 43.0% 456 52.1% 530 40.8% 677 Total embryos 58.5% 761 44.2% 1006 60.2% 881 47.9% 1107 59.4% 1642 46.1% 2113 1Lactating Holstein cows, first and second lactation, first service, Presynch-Ovsynch, 85 DIM. 2PR%=the number of pregnant cows divided by the number of cows that received and embryo; AdjPR%=adjusted pregnancy rate.

Contribution of intermediate filaments to cell stiffness, stiffening, and growth

2000 ◽  
Vol 279 (1) ◽  
pp. C188-C194 ◽  
Author(s):  
Ning Wang ◽  
Dimitrije Stamenović
Keyword(s):  
Mechanical Properties ◽  
Applied Stress ◽  
Extended Period ◽  
Direct Consequence ◽  
Cell Stiffness ◽  
Cell Integrity ◽  
Wild Type ◽  
The Difference ◽  
High Degree

It has been shown previously that intermediate filament (IF) gels in vitro exhibit stiffening at high-applied stress, and it was suggested that this stiffening property of IFs might be important for maintaining cell integrity at large deformations (Janmey PA, Evtenever V, Traub P, and Schliwa M, J Cell Biol 113: 155–160, 1991). In this study, the contribution of IFs to cell mechanical behavior was investigated by measuring cell stiffness in response to applied stress in adherent wild-type and vimentin-deficient fibroblasts using magnetic twisting cytometry. It was found that vimentin-deficient cells were less stiff and exhibited less stiffening than wild-type cells, except at the lowest applied stress (10 dyn/cm2) where the difference in the stiffness was not significant. Similar results were obtained from measurements on wild-type fibroblasts and endothelial cells after vimentin IFs were disrupted by acrylamide. If, however, cells were plated over an extended period of time (16 h), they exhibited a significantly greater stiffness before than after acrylamide, even at the lowest applied stress. A possible reason could be that the initially slack IFs became fully extended due to a high degree of cell spreading and thus contributed to the transmission of mechanical stress across the cell. Taken together, these findings were consistent with the notion that IFs play important roles in the mechanical properties of the cell during large deformation. The experimental data also showed that depleting or disrupting IFs reduced, but did not entirely abolish, cell stiffening. This residual stiffening might be attributed to the effect of geometrical realignment of cytoskeletal filaments in the direction of applied load. It was also found that vimentin-deficient cells exhibited a slower rate of proliferation and DNA synthesis than wild-type cells. This could be a direct consequence of the absence of the intracellular IFs that may be necessary for efficient mediation of mechanical signals within the cell. Taken together, results of this study suggest that IFs play important roles in the mechanical properties of cells and in cell growth.

scholarly journals Evidence for strategic egg production in a hermaphroditic cestode

Parasitology ◽  
1998 ◽  
Vol 117 (4) ◽  
pp. 373-382 ◽  
Author(s):  
C. WEDEKIND ◽  
D. STRAHM ◽  
L. SCHÄRER
Keyword(s):  
Egg Production ◽  
Maternal Investment ◽  
Social Situation ◽  
Egg Mass ◽  
Simultaneous Hermaphrodite ◽  
Intermediate Hosts ◽  
The Difference ◽  
Cross Fertilization ◽  
Hatching Rates

The cestode Schistocephalus solidus is a simultaneous hermaphrodite that grows in 2 intermediate hosts and reproduces rapidly within a few days in the gut of a bird. Reproduction takes place by self- or cross-fertilization. Here, it was tested whether egg production differs between S. solidus that reproduce alone and those that are allowed to reproduce in pairs. Egg production in an in vitro system was found to depend on the cestodes' social situation. When kept alone, larger cestodes produced larger eggs. This was not so when kept in pairs – the difference between these 2 reproductive modes being highly significant in this respect. Further experiments revealed that, within the first 3 days, these hermaphrodites produced a larger total egg mass when kept alone than when kept in pairs. This was also reflected by the energy contents of the cestodes after this time-span: selfers had used up more energy than paired worms. Furthermore, S. solidus appeared to adjust its investment per egg depending on whether the offspring will be the result of self- or cross-fertilization. Selfers produced larger numbers of eggs, but these eggs were smaller and contained even smaller embryos per given egg size than eggs of potentially outbreeding cestodes. Selfed eggs reached lower hatching rates. Although this is to be expected from inbreeding depression it may also be an effect of the reduced maternal investment per egg. The observed phenotypic plasticity in the reproduction of S. solidus is discussed within 4 evolutionary frameworks: local mate competition adjusted for hermaphrodites, the hermaphrodite's dilemma, bet-hedging, and sib-competition.

Étude de la croissance et du développement chez le frêne commun, Fraxinus excelsior, cultivé en conditions contrôlées

1995 ◽  
Vol 73 (9) ◽  
pp. 1464-1470 ◽  
Author(s):  
P. Collin ◽  
P. M. Badot ◽  
B. Millet ◽  
P. Barnola
Keyword(s):  
Growth Stage ◽  
Average Duration ◽  
Direct Consequence ◽  
Stem Growth ◽  
Fraxinus Excelsior ◽  
Histological Studies ◽  
Embryo Stage ◽  
The Common ◽  
Growth Development ◽  
Rhythmic Growth

Under controlled conditions (14 h light : 10 h dark; 27 ± 1 and 19 ± 1 °C), common ashes, Fraxinus excelsior L., display a rhythmic growth. The average duration of the first growth flush is 106 days, followed by a phase of nonlengthening from 9 to 11 months, depending on individuals. This rhythm was materialized in the shoot organization. The end of each growth stage was characterized by progressively shorter internodes and by the presence of scales around the bud. Histological studies reveal that no leaf is preformed at the embryo stage and that the meristem activity carried on after the stem growth stops. The common ash growth rhythm is therefore not the direct consequence of the arrest of meristem activity. The nonlengthening phase is an apparent resting phase during which the initiation of new leaves carries on. Key wordsff growth, development, common ash, meristem, plastochron, rhythm. [Author's translation]

scholarly journals Impact of nest sanitation behavior on hosts’ egg rejection: An empirical study and meta-analyses

2021 ◽  
Author(s):  
Qihong Li ◽  
Jianli Bi ◽  
Jiangwen Wu ◽  
Canchao Yang
Keyword(s):  
Empirical Study ◽  
Host Species ◽  
Brood Parasitism ◽  
Egg Rejection ◽  
Specific Adaptation ◽  
Potential Host ◽  
Nest Sanitation ◽  
Avian Brood Parasitism ◽  
Meta Analyses ◽  
The Relationship

Abstract Egg rejection in birds is a specific adaptation toward avian brood parasitism, while nest sanitation is a general behavior for cleaning the nest and avoiding predation. However, both behaviors refer to the action of ejecting objects out of the nest, and nest sanitation has been proposed as a pre-adaptation for egg rejection. Here we tested the eliciting effect of nest sanitation on egg rejection in the red-whiskered bulbul Pycnonotus jocosus, a potential host species that is sympatric with parasitic cuckoos. We conducted meta-analyses of previous studies on both nest sanitation and egg rejection, in order to evaluate the consistency of our conclusions. Our results showed that nest sanitation did not elicit egg rejection in P. jocosus. The conclusions concerning such an eliciting effect from previous studies were mixed, while the methodologies were inconsistent, making the studies unsuitable for comparisons. However, the ejection frequency of nest sanitation was consistently higher than the frequency of egg rejection across different host species or populations. These results suggest that nest sanitation, which is an ancient behavior, is more fundamental than egg rejection, but the effect of the former on the latter is complex and needs further study. Standardized methodologies and the integration of behavior, physiology, and modeling may provide better opportunities to explore the relationship between nest sanitation and egg rejection.

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