Method for efficiently promoting chlamys farreri larva attachment and metamorphosis by using levodopa

Abstract

The invention belongs to the field of shellfish culture, and particularly relates to a method for efficiently promoting chlamys farreri larva attachment and metamorphosis through levodopa. Aiming at the problem of low attachment and metamorphosis rate in the current chlamys farreri breeding process, the invention provides the method for efficiently promoting the attachment and metamorphosis of the chlamys farreri larvae by using the chemical inducer levodopa, and a technical support is provided for improving the attachment and metamorphosis rate in the chlamys farreri seedling production process.

Description

Technical Field

[0001] This invention belongs to the field of shellfish aquaculture, specifically relating to a method for efficiently promoting the attachment metamorphosis of scallop larvae using levodopa. Background Technology

[0002] As an important economic species of the class Bivalvia in the phylum Mollusca, the scallop *Ctenopharynx* suffers from larval mortality during metamorphosis, a major bottleneck in its large-scale seed production. During this stage, the larvae must complete key developmental events such as vegetative plate degeneration, foot development, and secondary shell formation. However, in practice, *Ctenopharynx* larvae frequently experience unexplained delayed metamorphosis and eventual death, with mortality rates reaching over 80%. Therefore, improving the metamorphosis rate of *Ctenopharynx* larvae is crucial for successful seed production. However, to date, no method has been found to solve the problem of low metamorphosis rates in *Ctenopharynx* larvae.

[0003] Previous studies on metamorphosis in Pacific oysters have found that L-DOPA can be absorbed by larvae and converted into DOPA, activating larval metamorphosis behavior; in hard-shell clams, L-DOPA has been found to regulate larval metamorphosis by activating the tyrosine hydroxylase pathway; and in mud clams, K... + Ca 2+ Metal cations can induce metamorphosis in larvae, but there are currently no studies on using levodopa to induce metamorphosis in scallop larvae. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a method for improving the metamorphosis rate of scallop larvae. When the number of eye-spot larvae in the scallop reaches 60%, the larvae are collected to a density five times that of the normal culture system, and then... -2 Scallop larvae were induced with mmol / L levodopa solution for 3-12 hours, and then cultured normally after induction.

[0005] Furthermore, the induction time is 6 hours.

[0006] The present invention also provides a scallop larva inducer, comprising levodopa.

[0007] The present invention has the following beneficial effects:

[0008] Adding levodopa to the aquaculture water effectively increases the attachment metamorphosis rate of the scallop. When the eyespot larvae of the scallop reach 60%, use 10 -2 When larvae were induced for 6 hours with mmol / L levodopa solution, the number of larvae was 5 times that of the normal culture system, and the attachment metamorphosis rate was as high as 66.67%, which was 37.36% higher than the control on average. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 Effects of levodopa treatment on metamorphosis of scallop larvae; C: control group; L: levodopa group. Detailed Implementation

[0011] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods used in the embodiments are conventional methods, and the reagents used are commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0012] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0013] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0014] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0015] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0016] Induction experiments were conducted at the Laizhou Seedling Farm in Yantai in April 2025. Using 10... -2 Inducing 6 hours of treatment with 60% eyespot larvae of the scallop *Ctenopharynx* using 6 mmol / L levodopa included the following steps:

[0017] 1. Experimental materials:

[0018] 1.1 Scallop larvae:

[0019] Scallop larvae with an eye spot larvae ratio of 60% were selected from the seedling farm in Laizhou City, Yantai in April 2025.

[0020] 1.2 Inducing reagent:

[0021] The reagent levodopa used in this experiment was purchased from MCE.

[0022] 2. Experimental methods:

[0023] 2.1 Preparation of levodopa solution: Prepare a 1 mmol / L levodopa stock solution using clean seawater, then dilute it to 10... -2 Working solution concentration: mmol / L. All solutions should be prepared fresh for each experiment.

[0024] 2.2 Induction of *Ctenopharynx scallop* larvae: *Ctenopharynx scallop* larvae with an eyepoint larval ratio of 60% were collected using 260-mesh sieve silk and induced in the working solution of step (1) for 6 hours. Simultaneously, ordinary *Ctenopharynx scallop* larvae without added levodopa induction solution were set as a control group, with three replicates in each group. The larval induction density was 20-25 larvae / ml, which is 5 times the larval density of the ordinary culture system. No feeding or water changes were performed during the induction period.

[0025] 2.3 Cultivation of *Scallop* larvae after induction; The larvae treated in step (2) were collected using a sieve, rinsed three times with filtered seawater, and placed in clean filtered seawater for continued aeration and cultivation. The larval density was 4-5 larvae / ml. After 1 hour of induced larval recovery, they were introduced into the substrate. The culture feed was *Isochrysis galbana*, fed four times a day. The culture temperature was 19-20℃, and the water was changed twice a day, half of it each time.

[0026] 2.4 Observation Records: Eight days after the induction treatment, the larvae completed their attachment metamorphosis. The number of larvae attached to the top and bottom of the attachment substrate in each group was counted, and the final metamorphosis rate was calculated. Metamorphosis rate = (Number of metamorphosed individuals / Total number of individuals) × 100%.

[0027] 3. Results:

[0028] The results are as follows Figure 1 As shown in Table 1.

[0029] Table 1. Effects of L-DOPA treatment on metamorphosis of scallop larvae.

[0030]

[0031] According to the data from the embodiment, using 10 -2 L-DOPA at mmol / L significantly increased the metamorphosis rate of scallop larvae in the experimental groups, with the highest metamorphosis rate reaching 66.67%, demonstrating a very good metamorphosis induction effect.

[0032] This invention selects levodopa as a metamorphosis inducer, which is safe and simple to operate; at the same time, it uses a 1 / 5 normal culture volume for induction, further reducing costs. This method provides the optimal induction concentration and time of levodopa, significantly improving the metamorphosis rate of larvae, with an average increase of 37.36%. Levodopa, as a neurotransmitter precursor, is environmentally friendly and can be applied in large-scale production. This invention can significantly improve the metamorphosis rate of scallop larvae, reduce the large-scale mortality caused by the inability to metamorphose normally during scallop farming, and provide an efficient and stable technical solution for large-scale seed production, which has important application value.

[0033] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for improving the metamorphosis rate of scallop larvae, characterized in that, When the number of eye spot larvae in the scallop reaches 60%, collect the larvae to a density of 1 / 5 of the normal culture system, and use 10 -2 Scallop larvae were induced with mmol / L levodopa solution for 3-12 hours, and then cultured normally after induction.

2. The method according to claim 1, characterized in that, When the number of larval eyespot larvae reaches 60%, inducement treatment is performed.

3. The method according to claim 1, characterized in that, The larval density during induction was 5 times that of the ordinary culture system.

4. The method according to claim 1, characterized in that, The induction time is 6 hours.

5. A scallop larvae attachment metamorphosis inducer, characterized in that, Including levodopa.

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