Squash Technique Research Articles

Accumulation of Heavy Metals and Their Genotoxic Potential in Medicinal Plant Verbacsum speciosum Schrad.

Background: Nowadays, the contamination of soil, water, and plants by heavy metals (HMs) presents a notable environmental problem. Methods: Lead (Pb) and zinc (Zn) levels in soil and Verbacsum speciosum populations were measured using atomic absorption spectroscopy, and meiosis in pollen mother cells (PMCs) was examined through the squash technique to evaluate genotoxic effects. Results: The results showed that Pb and Zn concentrations in the soil and, roots, and aboveground portions of all Verbacsum speciosum populations within the mining area exceeded permissible thresholds significantly. Particularly, the contaminated soil displayed average Pb and Zn concentrations of 3527.4±0.7 and 1671.4±0.5 mg/kg, respectively. The roots of Verbacsum speciosum plants closest to the mine exhibited the highest levels of Pb and Zn, measuring 204±0.05 mg/kg and 570±0.16 mg/kg, respectively. Additionally, the above-ground parts of the plants showed Pb and Zn concentrations of 312±0.12 mg/kg and 519±0.17 mg/kg, respectively. Moreover, the transfer factor (TF) for both Pb and Zn was found to be above one, indicating substantial accumulation of these metals in the above-ground portions. The presence of Pb and Zn also resulted in abnormalities during meiosis. As the distance from the mine increased, a decrease in the occurrence of meiosis abnormalities and an increase in the meiotic index (MI) were observed. Conclusion: These results highlight the potential risks to human health posed by industrial wastewater and the natural presence of HMs in soil. The ability of these metals to accumulate in plants and interfere with their meiosis underscores the importance of addressing and mitigating these hazards.

Cytogenetic and agro-morphological study of Wheat addition lines possessing Thinopyrum elongatum and Aegilops triuncialis chromosomes

Novel genetic variation can be induced by introgression of alien chromosomes in wheat for which wheat-alien addition lines carrying 45 chromosomes are instrumental. In the course of developing wheat addition lines with 45 chromosomes, two different parental lines Wheat-Thinopyrum elongatum disomic addition lines (Wheat-Th. DALs; 2n=44)) and Wheat-Th. elongatum- Aegilops triuncialis 3CSAT double monosomic addition lines (Wheat-Th. DMALs; 2n=44) need to cross. The present study mainly focuses on the effects of chromosomal additions in wheat background by comparing the morphological and agronomic traits of the parental lines. Both the parental lines were reconfirmed 2n=44 cytologically by using squash technique. Pollen fertility was highest (75%) in Wheat-3CSAT-6E DMAL and lowest (44.73%) in Wheat-5E DAL, whereas, spike length was longest (8.71 cm) in Wheat-3CSAT-3E DMAL and shortest (5.92 cm) in Wheat-1E DAL. Plant height was highest (97.6 cm) in Wheat-3CSAT-5E DMAL and lowest (55.33 cm) in Wheat-7E DAL. The plant height of DMALs always exceeded that of DALs. Furthermore, seed set was highest (31 seeds per spike) in Wheat-7E DALs and lowest (13 seeds per spike) in addition lines disomic for 4E chromosomes. The effect of different alien chromosomes in wheat is discussed in this paper.

Sex Ratio and production parameters of Oreochromis niloticus “Tilapia”

Oreochromis niloticus farming has been affected by excessive reproduction in cropping systems, which causes delayed growth and small sizes at harvest, becoming unmarketable, creating the need to reverse the sex of the females, being possible with hormonal sex reversal techniques such as 17 α methyltestosterone (MT). The objective of this research was to determine the sexual ratio and obtain the production parameters in specimens of O. niloticus with the MT hormone which was supplied in food at 45% protein, with a dose of 24 mg of MT/kg of food, for 28 days. Sex determination was carried out using the squash technique and microscope observation. The information was analyzed using descriptive and inferential statistics at 95% confidence in the Excel program. We worked with 10% of the total population, reaching 95.2% males. The gonads of the females showed oocytes, while in the gonads of males’ spermatocytes were observed, they presented a survival of 96.33%, an increase in weight of 13.46 g and length of 7.82 cm.

Assessment of Cytogenotoxicity of Plastic Industrial Effluent Using Allium cepa Root Tip Cells.

The effects of plastic effluent in Kano Metropolis on cytotoxicity and genotoxicity were examined using a test on Allium cepa root cells. The physicochemical characteristics of industrial wastewater were assessed, and the results showed values that were higher than the required criteria; this implies that the effluent was not treated before to disposal. For 96 hours, a group of 40 onion bulbs was cultivated in various concentrations of plastic effluent: 15, 30, 45, and 60% (v/v). The control was made up of distilled water. Following 96 hours, the four treated root tips from each replication's bulbs were harvested and subjected to the acetoorcein squash technique for cytogenetic analysis. High concentrations of the industrial effluents had severe development retarding effects on the root tips. Root growth was inhibited with EC50 values of 48% after treatment with the effluents in comparison to control. When Allium cepa was exposed to different quantities of plastic effluent, the results of an analysis of variance (ANOVA) showed that the mean root length varied, and this variation was statistically significant (p < 0.05). With rising effluent concentrations, the mitotic index (M.I.) rapidly dropped. Chromosomal abnormalities were caused by the plastic effluent in the root cells of Allium cepa, especially sticky chromosome and binucleated cells being the most frequently seen at lower concentrations of 15%. It was discovered that the compounds found in plastic wastewater could injure live beings as well as harm the environment if not treated. Legal mechanisms must be used to push businesses and manufacturers to switch to environmentally friendly technologies.

Preparation of Mitotic Chromosomes with the Squash Technique.

Plant chromosomes are usually obtained from meristematic tissue of active root tips through the conventional squash method. Nevertheless, cytogenetic work usually implies a great effort and some modifications of standard procedures need to be evaluated. In this chapter, we describe our outline for handling chromosomes using the squash method. By using these protocols, high-quality chromosome spreads are obtained, which allow chromosome counting, building karyotypes, and assessing chromosomal landmarks, and enable genome mapping by fluorochrome banding and in situ hybridization techniques.

First Report on Classical and Molecular Cytogenetics of Doi Inthanon Bent-toed Gecko, Cyrtodactylus inthanon Kunya et al., 2015 (Squamata: Gekkonidae) in Thailand

This study analyzed the karyotype of Cyrtodactylus inthanon Kunya et al., 2015 from Doi Inthanon, Chiang Mai Province, northern Thailand. The metaphase and meiotic chromosome preparations were obtained by squash technique from bone marrow and testes, respectively. The chromosomes were stained by Giemsa staining, Ag-NOR banding and molecular cytogenetics with ?uorescence in situ hybridization (FISH) using microsatellites d(CA)15, d(GC)15, d(CAG)10 and d(GAA)10 as probes. The results showed the diploid chromosome number (2n) of 40. The chromosome types of metacentric, submetacentric, acrocentric and telocentric chromosomes were 12-4-2-22, respectively. The Ag-NORs banding technique provides the pair of nucleolar organizer regions (NORs) on the telomeric region of the long arm of acrocentric pair 12. There are no sex differences in karyotypes between males and females. We also found that during metaphase I on meiosis of C. inthanon, the homologous chromosomes appeared synapsis of 20 bivalents. The microsatellite d(CA)15 signals were located on the sub-centromeric region of the metacentric pair 10, whereas the d(GC)15, d(CAG)10 and d(GAA)10 repeats are highly accumulated throughout almost all entire chromosomes. The karyotype formula is as follows: C. inthanon (2n = 40), Lm2 + Lsm4 + Lt6 + Mm2 + Mt8 + Sm8 + Sa2 + St8.

Chromosomal description of three Dixonius (Squamata, Gekkonidae) from Thailand

Chromosomal characteristics and karyological analysis of three Dixonius, including D. hangseesom, D. siamensis and D. melanostictus, from Thailand were studied. Chromosome preparations were conducted by squash technique from bone marrow and testis. Conventional Giemsa’s staining and Ag-NOR banding techniques were applied to stain the chromosome. The results showed that the diploid chromosomes are 2n=40, for D. hangseesom and D. siamensis; and 2n=42, for D. melanostictus. The fundamental number (NF) is 42 in D. hangseesom and D. siamensis and 44 in D. melanostictus. The types of chromosomes were 2 metacentrics and 38 telocentrics for D. hangseesom and D. siamensis, while the karyotype of D. melanostictus comprised 2 acrocentrics and 40 telocentrics. In the D. hangseesom and D. siamensis, NORs are located to the near centromere on long arm of the telocentric chromosome pair 13. Although, the NORs of D. melanostictus are situated on the subtelomeric region of telocentric chromosome pair 8. There are no sex differences in karyotypes between males and females of these three geckos species. We found that during metaphase I and metaphase II on male meiosis of the D. hangseesom and D. siamensis, the homologous chromosomes showed synapsis of 20 bivalents and 20 haploid chromosomes (n=20). Moreover, metaphase I and metaphase II of the male D. melanostictus showed synapsis of 21 bivalents and 21 haploid chromosomes (n=21). Their karyotype formulas is as follows: D. hangseesom (2n=40): Lm2 + Lt2 + Mt4 + St32, D. siamensis (2n=40): Lm2 + Lt6 + Mt4 + St28, and D. melanostictus (2n=42): La2 + Lt12 + Mt4 + St24.

Genotoxic and antigenotoxic potential of encapsulated Enhalus acoroides (L. f.) Royle leaves extract against nickel nitrate

Several environmental pollutants can cause damage to chromosomes, one of which is the heavy metal NiNO3. Some plant extracts have antigenotoxic properties that result in a decrease in chromosomal damage. Member of flowering plants that need to be tested is seagrass. One seagrass species is Enhalus acoroides which was found to contain phytochemical compounds. This study aimed to analyse the genotoxic effect and the potential of encapsulated E. acoroides leaf extract as antigenotoxic against nickel nitrate NiNO3. The extraction was conducted using a mixture of chloroform and ethanol, and crude extract encapsulated using maltodextrin and tween 80. Chromosomal aberrations were evaluated using the squash technique of Allium cepa var. aggregatum root tips. Triphenyltetrazolium chloride and Evans Blue staining were used to observe mitochondrial and apoptotic activities. The results showed that at higher concentrations (250 ppm and 500 ppm), the encapsulated E. acoroides extract decreased mitotic indices; however, no chromosome aberration observed. NiNO3 itself induced a genotoxic effect as observed by low mitotic index and a high percentage of chromosome aberration. The modulation of NiNO3 effect by adding the encapsulated E. acoroides extract at low concentration (100 ppm) increased mitotic index compared to treatment with Ni alone, but did not reduce chromosome aberration. Simultaneous encapsulated E. acoroides extract and Ni treatment, significantly reduced nuclear fragmentation and nuclear lesion. The encapsulated E. acoroides extract can repair several types of nuclear damage but cannot minimise chromosomal damage.

Genetic Diversity Assessment of Iranian Kentucky Bluegrass Accessions: II. Nuclear DNA Content and Its Association with Morphological and Geographical Features.

Poa pratensis L. is a perennial turfgrass with high regeneration and fertility, resistance to cold and drought, and quick colonization. By facultative apomixis, this plant can create a wide range of ploidy levels (2n = 22 to 2n = 154), resulting in a wide range of chromosomal numbers and sexual and apomictic reproductive diversity. The plant materials included fifty accessions from Iran's Center, South, North, North-East, North-West, and West ecoregions. UPOV standards were used to measure the qualities that were researched. The squash technique of chromosome counting revealed that Iranian Kentucky bluegrass accessions had chromosomal counts ranging from 24 to 87. The relative sizes of the 2C genomes were measured using laser flow cytometry. The range of DNA content was fairly wide, ranging from 4.92 to 11.52pg. DNA content has a strong positive correlation with elevation, a moderately positive correlation with flag leaf length and leaf sheath width, and a negative correlation with inflorescence anthocyanin color and leaf anthocyanin color. The genotypes and ecological zones of this plant in Iran were distinguished based on morphological diversity and DNA content. The results from this study could be useful in identifying and studying wild Kentucky bluegrass genotypes. It aids in predicting the location of rare genotypes used as breeding materials. It can also increase the plant's variability for future generations by introducing new ecotypes, with particular genomicand morphological traits, to previously cultivated populations. We expect that the findings of this study will aid in understanding the evolution of this plant in the context of Iran's climatic variety.

A Preliminary Study of Apomictic Characteristics of ‘Mianli’ (Pyrus sinkiangensis Yü)

This study investigated the ploidy of ‘Mianli’ with flow cytometry and the traditional chromosome squash technique. Its pollination biology and the occurrence and formation of embryo sacs before and after flowering were observed in paraffin sections to characterize its embryo sacs. The intersimple sequence repeat (ISSR) marker technique was used to test the uniformity of progeny of ‘Mianli’ treatments. The chromosome number of ‘Mianli’ is 2n = 2x = 34. The ploidy results were consistent with those identified by flow cytometry. ‘Mianli’ is male-sterile, and the anatropous ovule has double integuments. ‘Mianli’ can bear fruit normally and produce fertile seeds under the treatments of emasculation with bagging or no emasculation with bagging, but the seed yield is very low and significantly lower than that under artificial pollination or natural pollination. The developmental process of embryo sacs under natural pollination showed that most megasporocytes develop into mature sexual embryo sacs through meiosis and a few megasporocytes degenerate. Some sexual embryo sacs continue to develop into embryos after fertilization, and some sexual embryo sacs are aborted. In addition, new aposporous initial cells are generated irregularly at each stage from the emergence of megasporocyte to the end of sexual reproduction or abortion. The observation of the development of embryo sacs under emasculation with bagging showed that after pollination is blocked, mature sexual embryo sacs degenerate, and aposporous mononucleate embryo sacs appear around the degenerated sexual embryo sacs or in the peripheral tissues. Then, the process of proembryonic masses developing into spherical embryo was observed. A genetic uniformity analysis of progeny of ‘Mianli’ using ISSR was performed. The results showed that the progeny population under emasculation with bagging has high consistency at the molecular level, with some plants having full consistency with the female parent’s banding pattern, demonstrating consistency with the maternal genetic characteristics. The progeny under artificial pollination or natural pollination do not have the same banding pattern as the female parent. Because there is no pseudogamy, all of the progeny are true hybrids. In summary, it seems that ‘Mianli’ only has sexual reproduction in the presence of pollen, and only a few ovules are stimulated to undergo apomixis after pollination is blocked.

An Improved Fully Homomorphic Encryption Scheme for Cloud Computing

Business in cloud computing is very popular among Small and Medium Enterprises (SMEs). By leveraging services from the cloud, such companies can migrate all of their in-house operations to cloud at low costs with minimum IT facility requirements such as desktop machines and the Internet. Even though the cloud promises tremendous advantages in terms of computing resources and storage spaces, some of the companies are still reluctant to adopt such a technology because of security concerns. To overcome such problems, a fully homomorphic encryption (FHE) scheme with improved efficiency can be implemented as the scheme allows computation on encrypted data without decryption. In this paper, we propose an improved FHE scheme that uses a symmetric key for encryption together with a protocol to implement the scheme. Furthermore, we also provide an analysis regarding to the noise growth in the processed ciphertext and squashing technique that is required to reduce the noise. This analysis is essential to improve the efficiency of the scheme as the squashing technique is time-consuming.

TOXICITY ASSESSMENT OF BIOREMEDIATED CONTAMINATED DOMESTIC WATER SOURCES IN WESTERN NIGER-DELTA BY A PHYTOGENOTOXICTY TEST

In this study, fungal mycelium was employed for the bioremoval of heavy metals in drinking water samples obtained from boreholes, streams and a pond in six rural communities in Warri North Local Government Area in Delta State. The efficacy of the fungal-based bioremediation technology for toxicity reduction in the contaminated water samples was evaluated using Allium cepa cyto-genotoxicity bioassay in vitro approach before and after treatment with the fungal biofilters. Data obtained from physicochemical analysis after a 24 h myco-filtration treatment of the water samples revealed significant (p &lt; 0.05) reduction/total elimination of heavy metals and microbial load in the samples. Results obtained from the 96 hour macroscopic evaluation of A. cepa showed that, compared to onions grown in untreated samples, there was significant (p &lt; 0.05) reduction in root growth inhibition in onion bulbs cultivated in mycofiltrated samples. Similarly, results obtained from cytological studies by the aceto-orcein squash technique in root tips of A. cepa grown in the contaminated water samples for 48 hours showed significant (p &lt; 0.05) reduction in chromosomal aberrations. These findings indicate that the reduction in genotoxicity established by the Allium bioassay is highly correlated with myco-filtration bioremediation of the contaminated drinking water sources.

Assessment of Cytotoxicity and Genotoxicity Potential of Effluents from Bahir Dar Tannery Using Allium cepa

Tannery effluent plays a significant role in increasing pollution in the environment; in particular, it contains toxic heavy metals which cause toxic effects on plant genetic materials. Among tannery effluent chemicals, chromium and lead have cytotoxicity and genotoxicity potentials on Allium cepa. This investigation was undertaken to assess the physicochemical properties of tannery wastewater and their effect on the genetic materials of A. cepa. Effluent’s physicochemical characteristics were investigated using digital instruments for direct measurement and standard methods of atomic absorption spectrophotometer colorimetric analysis. A series of six onion bulbs were grown in 0%, 20%, 40%, 60%, 80%, and 100% concentrations of wastewater (v/v) ratio, and root tips from each onion bulb were cut and processed for analysis by aceto-orcein squash technique. Most of effluent components were above the discharge limit standards set by Federal Environmental Protection Agency and Ethiopian Environmental Protection Authority. The cytotoxicity effect on the root growth showed a significant reduction at high concentration. Simple regression analysis showed that the results of mitotic index were statistically significant (P &lt; 0.05) in different concentrations. A decrease in mitotic index with increasing concentration of the effluent was observed. The effluent had induced chromosomal abnormalities such as laggard, fragmentation, stickiness, bridge, micronucleus, and binucleated and morphologically changed nuclei in A. cepa root cells among others. The results showed that cytotoxicity, genotoxicity, and chromosomal aberrations were induced by the tannery effluent. Industries shall think of biological waste treatment methods.

Comparative Evaluation of Different Diagnostic Tests for Bovine Sarcocystis in Telangana Region of India

Bovine sarcocystosis is a widely prevalent disease, causing significant impact on animal and public health throughout the world. During this study, oesophageal and diaphragmatic muscle samples collected from 100 cattle and buffaloes slaughtered at Chengicherla slaughter house, Hyderabad, were subjected to macroscopic and squash examination and pepsin HCl acid muscle digestion techniques. The sera of the animals were also screened for anti-Sarcocystis antibodies by IFAT. Gross macroscopical examination revealed the presence of macrocysts in 16.0 and 0% of oesophageal and diaphragmatic muscles, whereas squash and HCl pepsin method muscle digestion techniques revealed microcysts is 8.0 and 0% and bradyzoites in 76.0 and 52.0% of the samples, respectively. Immunofluorescent antibody test (IFAT) showed higher sensitivity in the diagnosis of bovine sarcocystosis followed by muscle digestion, macroscopic examination and squash techniques with positivity rates of 82.0,76.0, 16.0 and 8.0%, respectively. The present study suggests IFAT as a sensitive and specific test when compared to conventional diagnostic methods for ante mortem diagnosis of bovine sarcocystosis.

Mutagénesis in vitro en auturio inducida mediante colchicina

Developing new varieties of anthurium by hybridization can take 8-10 years; therefore, induced mutagenesis can be an alternative strategy to hybridization. The objective of this work was to induce mutations in A. andreanum by exposing explants obtained from vitroplants to colchicine. Explants of leaves, nodes and roots obtained from vitroplants were exposed to 0.1 % colchicine for 0, 2, 3 and 4 h. The mean lethal dose (LD50), survival, number of explants that generated callus, number of explants that formed shoots and the number of shoots per explant were evaluated. The karyotype of the presumed mutated regenerated plants was determined by the root apex squash technique. The leaves showed the highest sensitivity to cochicine. The survival of the root explants treated with colchicine was 100 %; 4 % of roots exposed for 2 and 3 h formed adventitious shoots (120 shoots). For nodes, the LD50 was found at 3.98 h; 76 and 56 % of the nodes cultivated for 2 and 3 h with colchicine formed adventitious shoots (4.4 and 3.6 shoots). The plants regenerated from the explants exposed to colchicine showed morphological changes. The chromosomal number of the regenerated vitroplants from the explants exposed for 2 and 3 h to colchicine was 2n = 29, while that of those obtained from the explants that remained on the colchicine for 4 h was 2n = 31. The sensitivity to colchicine was a function of the type of explant and the dose used. Colchicine caused the loss (monosomy) or gain of chromosomes (trisomy).

The optimum dose and period of 17α-methyltestosterone immersion on masculinization of red tilapia (Oreochromis spp.)

This study was carried out to examine the effect of combining factors for immersion technique on masculinization of red tilapia (Oreochromis spp.). Three selected doses (1000, 1,500, and 2000 μg/L) of 17α-methyltestosterone (17 MT) immersion, 2 exposure times (3 and 6 h) once or twice a week, and interaction of these factors were tested. A total of 12 treatment combinations under 3 × 2 × 2 factorial experiments in randomized complete block design were conducted to compare with the negative control group (no 17 MT-treated) and positive control group (17 MT-treated feed administration). One hundred red tilapia larvae (14 days post-hatch) were randomly allocated in each treatment and were operated in a 10-L glass jar for 21 days. At the end of the treatment regime, the survival rate was determined. Then, fish were raised in a 150-L glass tank using normal commercial feed for 2 months and sex ratios were determined via the gonad squash technique. None of the immersion treatments tested resulted in a statistically significant (p > 0.05) decrease in survival rate. All 17 MT-treated groups produced progenies with a significantly higher (p < 0.001) proportion of males than the predicted 1:1 sex ratio. Influences of some factor combinations in the masculinization of red tilapia were observed. The male ratio was significantly affected by the dose-period and dose-frequency treatments (p < 0.05). The highest male proportion (95.33% ± 0.58%) was recorded at 1000 μg/L of 17 MT for 6 h once a week which was significantly higher (p < 0.05) than other groups. The production cost of the best group was the cheapest (THB0.0066/fish) and decreased from the traditional procedure by about 10.81%. Therefore, this technique could be implemented for decreasing cost and operating process in commercial tilapia farms.

The Mitotic Index of Cajanus cajan from Kisar Island, in the Southwest of Maluku

The mitotic index of the roots of pigeon pea can be the basis for determining the growth of pigeon pea. The purpose of this research was to determine the time of root cell division, to observe the mitotic phases, and to determine the mitotic index of pigeon pea root cells. The preparation of the pigeon pea was carried out for 4 days to grow the roots. The roots were cut off at 08.00, 08.15, and 08.30 WIT (Eastern Indonesian Time). The roots were cut 0.5-1cm. Carnoy’s solution was used as the fixative solution using the Squash technique. The prepared roots were then observed using an Olympus cx-22 microscope and an OptiLab camera with a magnification of 100x40. The data were descriptively analyzed to describe the images of mitotic phases and the mitotic index presentation in the root cells of pigeon pea. The results of this research showed that the cell division of the pigeon pea roots began at 08.00 WIT, which was marked by the presence of a lot of prophase. The next phases that appeared were prometaphase, metaphase, and anaphase which occurred from 08.15 to 08.30 with different numbers. The highest mitotic index occurred at 08.15, when most of the root cells underwent metaphase. This study succeeded in revealing that the optimum time for pigeon pea root cell division is 08.15 WIT. In the future, this research can help pigeon pea farmers in Southwest of Maluku to carry out vegetative reproduction which is closely related to this mitotic study.

Tropical Wetland Earthworm Vermifluid Promotes Mitotic Activities and Root Growth in Allium cepa at low concentrations

It is well established that earthworms and their products promote plant growth and improve crop yield, but more information about their mechanisms of action, especially at cellular level, is required. This study assessed the enzyme and bacterial activities of vermifluid secreted by a tropical wetland earthworm, Alma millsoni. The effects of the vermifluid on the mitotic activities and root growth of Allium cepa (onions) were evaluated. Vermifluid enzyme and bacterial activities were assessed using standard procedures. Mitotic activities were evaluated using the Allium assay squash technique. Root lengths in onions grown in graduated dilutions of vermifluid were measured using a metre rule. Phosphatase had the highest activity (39.00 ± 3.70 units/ml/min) in the vermifluid, followed by urease (4.90 ± 0.18 units/ml/min), protease (3.20 ± 0.28 units/ml/min), amylase (1.40 ± 0.09 units/ml/min) and lipase (0.001 ± 0.00 units/ml/min). The total microbial count (TBC) and total fungi count (TFC) in the vermifluid were 6.0 × 104 CFU/ml and 2.4 × 105 CFU/ml, respectively. Results also indicated that the lower the vermifluid concentrations, the higher the number of dividing cells and mitotic index in onion roots. Onion roots grown in 10% vermifluid had the highest significant (P &lt; 0.05) root growth of 2.65 ± 0.30 cm, 4.01 ± 0.61 cm, and 4.54 ± 0.62 cm, at 12-hour, 24-hour, and 72-hour exposure period, respectively. The inverse relationships between onion mitotic activities, root growth and vermifluid concentrations imply that the growth-promoting enzymes and other products in vermifluid stimulate cellular root growth better in small concentrations. Keywords: Alma millsoni, earthworm fluid, enzymes, microbial activities, mitosis, phosphatase.

Evaluation of mitotic activity in tapetal cells of grapevine (Vitis L.)

The knowledge with reference to the grapevine tapetum has been centered on its anatomy/morphology and hardly anything at all is known about its mitotic activity throughout the microsporogenesis. The aim of this study was to ascertain the mitotic activity in tapetal cells of some grapevines (Vitis L.) broadening knowledge about this tissue and simultaneously corroborating the viability of its use as an alternative tissue for further cytogenetic studies. Young buds of 12 grapevine varieties at different meiotic stages were squashed and tapetal cells a prometaphase/metaphase scored in each meiotic stage. Mitotic activity was observed since the beginning of microsporogenesis, where it was more intense, decreasing toward tetrad. Polyploid tapetal cells arose through endomitosis while the microsporogenesis advanced. Two types of polyploid cells were evidenced, those with two or more individualized diploid chromosome groups and those with only one polyploid group. The percentage of diploid cells and of polyploid cells with two or more individualized diploid groups was higher during the first stage of microsporogenesis, though decreasing and giving way to cells with one large polyploid group as microsporogenesis moved toward tetrad. The nucleolus number was scored at interphase at different stages. Two and four nucleoli prevailed in tapetal cells at all stages except at tetrad where one large nucleolus was seen. The results showed that despite of the squashing technique applied, grapevine tapetum has a substantial amount of cells with mitotic activity with a satisfactory chromosome spreading therefore establishing an interesting alternative and promising tissue for later cytomolecular studies.

Evaluación del periodo de masculinización en la tilapia del Nilo var spring empleando 17α-metiltestosterona

Una alternativa para reducir el uso de hormonas con aplicación inmediata en el cultivo comercial de la tilapia del Nilo, es la evaluación precisa de los tiempos de masculinización en variedades domesticadas. El objetivo del trabajo fue evaluar el porcentaje de masculinización y el crecimiento obtenido en la tilapia del Nilo alimentada con alimento comercial adicionado con 17α- metiltestosterona a diferentes tiempos. Para ello se evaluaron cinco tiempos (0, 10, 15, 20 y 25 días) de administración de hormona a una población mixta de tilapia del Nilo variedad Spring. Para cada tratamiento se utilizaron tres réplicas. Los alevines fueron sembrados a densidad de 0.5 alevines L−1 en un sistema de recirculación cerrado. El cultivo consistió de 30 días en acuarios de acrílico de 85 L y 20 días en tanques exteriores de 1000 L. La determinación del sexo se realizó con la técnica de squash. El crecimiento se determinó por medio del peso húmedo y la longitud total obtenida de las biometrías. Los resultados indican una masculinización del 100% desde los 10 días de aplicación del esteroide, pero los mayores valores de crecimiento se observaron en los grupos que recibieron el esteroide por mayor tiempo. Los resultados muestran que no es necesario administrar el esteroide durante 30 días para lograr una masculinización del 100% en variedades domesticadas y que el esteroide tiene efecto positivo en la tasa de crecimiento de los alevínes, persistiendo por algunas semanas después de terminado el tratamiento.