Sperm cryopreservation of Indian major carp, Labeo rohita: cryodiluents, sperm: cryodiluent dilution ratio and cryoprotectan t concentration

Cryogenic preservation trials of spermatozoa of Labeo rohita were carried out. Twenty four cryodiluents (extender + cryoprotectant), with the combination of six extenders such as egg-yolk citrate, urea-egg-yolk, 0.9% NaCl, Kurokura-2, Ma and Mb and four cryoprotectants viz. DMSO, glycerol, methanol and ethanol, were used to screen out the suitable cryodiluents. Sperm was preserved in 0.25ml plastic straw in programmable freezer. Two step freezing method was followed. Sperm preserved with egg-yolk citrate and urea-egg-yolk containing 10% DMSO showed best post-thaw motility (80%) followed by 0.9% NaCl (60%) and Kurokura-2(30%) solutions. Sperm with the extenders M" and Mb clotted at the time of equilibration and also after few days of preservation. Egg-yolk citrate mixed with ethanol and methanol also showed good percentage of motility (80%) but egg-yolk citrate with glycerol showed less sperm motility (>60%). To determine suitable dilution ratio of milt and cryodiluent two best extender eggyolk citrate and urea-egg-yolk with four cryoprotectants such as DMSO, glycerol, methanol and ethanol at different ratio viz 1:2,1:4,1:7,1:10,1:15 and 1:20 were used. Highest post-thaw motility (>80%) was observed when milt was preserved with egg-yolk citrate containing 10% DMSO at 1:2, 1:4, 1:7 and 1:10 dilutions. Meanwhile using glycerol as cryoprotectants provided less post thaw motility at lower dilution ratio but with the increase of its dilution showed good sperm motility compared with other cryoprotectants. Finally, evaluation on the effect of cryoprotectant concentration on post-thaw sperm motility was conducted. Egg-yolk citrate and four cryoprotectant i.e. DMSO, glycerol, methanol and ethanol with six different concentrations namely 5%,7%, 10%, 15%, 20% and 30%.were evaluated. Among the cryoprotectants DMSO, methanol and ethanol showed highest post-thaw motility (about 80%) at 7% and 10% concentrations. Although glycerol was not suitable at low concentration but its 20% and 30% concentration levels provided best post-thaw motility. No post-thaw motility was obtained with DMSO at 30% concentration. The overall analysis on cryoprotectant concentration indicated that below 5% and above 20% cryoprotectant concentrations could not be suitable for effective cryopreservation of spermatozoa

Red seaweed liquid fertilizer increases growth, chlorophyll and yield of mungbean (Vigna radiata)

Received: October 29th, 2022 ; Accepted: February 12th, 2023 ; Published: April 3rd, 2023 ; Corresponding author: [email protected] demand for chemical fertilizers in Bangladesh is increasing by the day. Seaweed extracts are high in a variety of bioactive substances that can be used as a biostimulant as an alternative to agricultural plants. To assess the impact of foliar spraying of red seaweed (Gracilaria tenuistipitata var. liui) extracts at 5, 10, 15, 20 and 25% concentrationsin comparison to the control condition (water spray only) and soil application of recommended doses of fertilizer (RDF) as basal on growth, chlorophyll and yield of mungbean variety BU mug5, a pot experiment was conducted at the Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh during Kharif-1 season (March to May 2021). Seven (7) treatments: T1 – Control (foliar spray using water), T2 – Recommended doses of fertilizers (RDF) as basal, T3 – Foliar spray of 5% seaweed extracts, T4 – Foliar spray of 10% seaweed extracts, T5 – Foliar spray of 15% seaweed extracts, T6 – Foliar spray of 20% seaweed extracts and T7 – Foliar spray of 25% seaweed extracts were imposed following completely randomized design (CRD) with three replications. The results revealed that seaweed liquid fertilizer at 20% concentration increased leaf area, total dry matter and chlorophyll (SPAD value) by 25.00, 40.21 and 9.11% over the control and 15.42, 8.27 and 2.08% compared to RDF, respectively. Seed yield increased by 93.14% when compared to a control with 20% seaweed foliar spray, and by 9.04%, when compared to RDF. Foliar application of 20% seaweed liquid fertilizer performed best among the treatments in terms of mungbean growth and yield, according to findings of the experiment. The results of this study suggest that red seaweed extracts from Gracilaria tenuistipitata var. liui may be used as a fertilizer to reduce the chemical fertilizer to boost mungbean yield

Distribution, prevalence and intensity of protozoan and monogenean parasites of carp fingerlings in selected nursery ponds

An experiment was carried out on the distribution, prevalence and intensity of infestation of protozoan and monogenean parasites of carp fingerlings in two selected areas of Bangladesh. Six hundred and forty fingerlings of seven species viz. Catla calla, Hypophthalmicthys molitrix, Labeo rohita, Ctenophalyngodon idella, Cyprinus carpio, Barbodes gonionotus and Cirrhinus cirrhosus from different nursery ponds of Shambhuganj, Mymensingh, and Santaher, Bogra were examined during this investigation. This study revealed that carp fingerlings carried a large number of protozoan and monogenean parasites. Different protozoan parasites viz Trichodina domerguei, Trichodina reticulata, Myxobolus koi, Chilodonella cyprini and monogenean parasites such as Dactylogyrus extensus, Dactylogyrus catlarius and Dactylogyroides tripathi were identified in the experimental fishes throughout the study period. It has been observed that distribution, prevalence and intensity of parasite in carp fingerlings are species and zone specific. In case of C. cirrhosus, the highest prevalence of protozoan parasite viz Trichodina domerguei were 93.75% and 75.92% in Santhahar and Shambhuganj area respectively. Irrespective of host, the most prevalent ectoparasite was Dactylogyrus extensus, followed by Myxobolus koi, Chilodonella cyprini and Dactylogyroides tripathi. Relatively higher mortality of carp fingerlings was found at younger stage. The highest prevalent parasitic species was identified as Trichodina domerguei followed by Trichodina reticulata and Dactylogyrus catlarius were found 93.75% in Cirrhinus cirrhosus, 68.75% in Cyprinus carpio and 39.44% in Hypophthalmicthys molitrix respectively

Milt quality determination of a critically endangered fish, olive barb (Puntius sarana, Ham.) in Bangladesh

The present study was aimed to evaluate the characteristics of the olive barb sperm. Milt was collected fortnightly from 49 male fish (mean weight 90.8 g and length 18.64 cm) from April to July in 2008. In the olive barb ejaculated milt, volume (µl/g), motility (%), duration of motility (s), concentration (x 10 super(10)/ml) and pH values were found to be 6.06±0.32, 88.27±0.71, 171.41±7.41, 5.16±0.05 and 7.75±0.04, respectively. Milt volume was significantly (P<0.05) correlated with sperm concentration. Milt volume, sperm concentration, motility and duration of motility significantly varied (P<0.05) during spawning season

GENETIC DIVERSITY OF WILD AND FARMED KALIBAUS (Labeo calbasu, Hamilton, 1822) BY RAPD ANALYSIS OF THE GENOMIC DNA

Genetic diversity of two wild Kalibaus, Labeo calbasu populations and one hatchery stock was studied using random amplified polymorphic DNA (RAPD) method. The three 10–mer random primers (OPA01, OPB02 and OPC03) yielded a total of 26 reproducible and consistently scorable RAPD bands of which 15 (57.69%) were considered as polymorphic (P95) indicating a high level of genetic variation in all the studied populations. Among the three populations, Padma population shows low level of genetic diversity (0.1238) compared to other two and it might be caused by habitat degradation in many ways which ultimately affects the genetic variation of Kalibaus. The UPGMA dendrogram based on Nei’s (1972) original measures of genetic distance (D) indicated the segregation of two wild and hatchery populations of L. calbasu into two distinct clusters: the Hatchery and Padma populations produced one cluster whereas the Jamuna population belonged to another cluster. This indicates that hatchery brood stock is derived from Padma River. Nevertheless, the preliminary study revealed that RAPD technique could be an effective tool in the assessment of population genetic structure of Kalibaus

Cryopreservation of spermatozoa of Mrigal, Cirrhinus cirrhosus with a view to minimize inbreeding and hybridization

To develop and standardize the cryopreservation protocol of C. cirrhosus sperm, a series of experiments were conducted. Seven extenders, egg-yolk citrate, urea egg-yolk, 0.9% NaCl, Kurokura-2, Ma and Mb and four cryoprotectants viz. DMSO, glycerol, methanol and ethanol were used to find out the suitable cryodiluent. Among the cryodiluents egg-yolk citrate with DMSO yielded (mean±SD) highest post-thaw motility (83%±5.70) that was closely followed by egg-yolk citrate with methanol (81%±6.51) and urea egg-yolk with DMSO (79%±6.47). Six dilution ratios such as 1: 2, 1: 4, 1: 7, 1: 10, 1: 15, and 1: 20 (milt:cryodiluent) were used to determine the suitable milt dilution and found that sperm motility percentage increased roughly with the increase of dilution ratio. Different dilution ratios exhibited marked differences in the post-thaw spermatozoan motility (P=0.000) and revealed that it has an interaction effect with the extenders (P0.05). To determine the optimal cryoprotectant concentration, an increasing series of cryoprotectant concentrations from 5 to 30% (v/v) were tested. DMSO at 10% concentration produced averagely highest post-thaw motility with all three extenders. Methanol and ethanol produced best result at 10% concentration but their lower (20%) concentrations decreased spermatozoan motility

First Report of the Red Algal Genus Chondria C. Agardh (Rhodomelaceae, Rhodophyta) for the Marine Flora of Bangladesh

Epiphytic algae in mangrove forests contribute to high productivity in these unique mangrove ecosystems. A general survey of mangrove-associated macroalgae was conducted during February&ndash;March (dry season) and November&ndash;December (wet season) in the Sundarbans Mangrove Forest, Bangladesh. Different macroalgae were collected from mangrove pneumatophores, roots, and branches of trees. During this survey, a small and inconspicuous species of Chondria was encountered from the upper-middle of the intertidal zone in the Malancha River (22&deg;5&prime;11.37&Prime; N and 89&deg;13&prime;12.37&Prime; E). External&ndash;internal anatomical traits were examined and the sample was identified as Chondria intertexta Silva, a new record for the algal flora of Bangladesh. Furthermore, its geographical distribution and some other ecological notes are also discussed