species, Portunus sanguinolentus collected from the coastline of Karachi, Pakistan.

Title

9657-SEReferee Marked Copy

Elemental detection in the Shell of Economically important crab

1Wajeeha Razzaq, Zubia Masood* , Nosheen Rafique , Nelofer Jamil, Rehana Yasmeen

Farooq, Musarrat-ul- Ain , Farhat Iqbal.

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5 1

2,5 1 3,4 5

Department of Zoology Sardar Bahadur Khan Women’s University, Quetta, Balochistan.

2Department of Zoology, Jinnah University for Women, Karachi, Pakistan

3 Department of Environmental Sciences, SardarBahadur Khan Women’s University, Quetta, Balochistan, Pakistan4

Department of Chemistry, SardarBahadur Khan Women’s University, Quetta, Balochistan, Pakistan 5 Department of Zoology, University of Karachi-75270, Karachi, Pakistan

*Corresponding Author: Zubia Masood

Abstract

Present study was conducted to detect some elements in shells of a crab species i.e.,

Portunus sanguinolentus collected from Karachi seashore during the months of January to

March 2017. A total of 30 crab shell samples were collected and divided into three replicates (10

shells for each samples). The metal detection was performed by Element detection System (EDS)

with scanning electron microscope (SIM). The results of these three replicates revealed that crab

shell contain the elements including, i.e., 8.76 to 20.6 % Carbon (C), 32.0 to 58.8 % Oxygen (O),

18.8 to 55.7% Calcium (Ca), 0.00 to 3.55% Copper (Cu), 1.68 to 1.75 % Magnesium (Mg), and

0.0 to 2.98% Phosphorus (P) in variable quantities in each replicate, respectively. Thus, it was

concluded that crab shells are the valuable source of certain important minerals particularly

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calcium that can be utilized in preparation of products for pharmaceuticals and also a beneficial

source of certain minerals for humans in the future.

Key words: Elements, Crab shell, Portunus sanguinolentus, Karachi coastline.

Introduction

The crab Industry has been developed and also served as important food resources for

many years in international and national souks. Crabs are very famous and according to their

ranking, they are considered as third sea food besides the lobsters and shrimps for their venerated

delicacy among seafood and in addition to the value of their support to fishery [1]. Chitin is a

polysaccharide that is widely found it is biodegradable as well as non-toxic .It is composed of N-

acetyl-D Glucosamine units that are linked by β-1,4 bonds. It is well-known because basic

buildings block of the various arthropods shells as well as for shrimp, lobster, octopus, crab,

fungi, nematodes, squid, green algae and jellyfishes. It is also important constituent of

exoskeletons of the most abundant and successful creatures that are insects. The antimicrobial

activity of chitin is renowned and it has been subjugated in the dentistry to get rid of dental caries

and it has also been utilized as preservative appliances in the packaging of in various parts of the

world [2-5]. Chitin of crab shell is efficacious agent that helps to inhibit bacterial growth [6]. The

swimming or Portunid crabs are major fishery resources of the seas of South East Asia. The most

important species of these crabs includes Portunus sanguinolentus, also known as “three spotcrab” and Portunus pelagicus that is commonly known as “blue swimming crab” as well as

“flower crab”. These three species of crabs have elevated value from commercial perspective.

Blue crabs’ crabbing is famous and they are fished in bulk particularly in seas of various

countries that include Bangladesh, India, Arab countries and Southeast Asian countries [7], and

is considered as very importance for medical point of view, as it is usually recommended by

doctors to pregnant women [8]. Crab has high levels of amino acids that help to control various

diseases that includes inflammatory diseases

diseases.

and Crohn‟s disease. Crab is also used in

medicines as protective agent against development of rheumatoid arthritis and cardiovascular

Materials and Methods

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A total of 30 samples of a Crab shells of a species known as Portunus sanguinolentusshell samples were collected from the beach of Karachi during January to March 2017. Portunussanguinolentus shells and their Residues were instantaneously shifted to Laboratory of

department of Zoology, University of Karachi, and then there, these samples were rinsed

carefully using sterile distilled water. These shells were then identified upto specie level using

identification keys and pictorial keys (Bianchi, 1985). Samples were then divided in to three

replicates (10 shells for each sample). After credentials sample were instantly kept on digital

balance and dry weight of the samples were measured in grams before grinding them in to

powder using mortar. Grinding was applied to the shell and then 10g of powdered shell was

stored in cleaned polythene bags and was sent to laboratory for elemental detection as shown in

Figs. 1 and 2, respectively.

Fig. 1. Crab shells of Portunus sanguinolentus

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Fig. 2. Crab shell and its sampling pictures

Fig. 3 showing Scanning Electron Microscope (SIM) Images of Crab shell powder.

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Results and Discussion

As in the present investigation, as three replicates each sample that is, A, B and C were

tested and the percentages of each element were recorded accordingly in Table 1. While simple

camera images and SEM images of shell has also been taken that are represented in Fig. 3,

respectively. The Oxygen was most abundant and the trend of elements has following order

asfollows; Oxygen>Calcium>Carbon>Copper>Magnesium and Phosphorus was being lowest in

quantity.

Table 1. Percentage composition of each Element in three replicates of crab shell from Karachi coast.Element Symbol Quantity of elements in three

replicate, A, B & C (10 shellfor each) in percentage (%)

TotalMean± Standardamount of Deviation (S.D) eachelement inpercentage

41.00144.76104.28 3.55 3.43 2.98

1.36±6.1748.3±14.334.7±18.91.18±2.041.14±0.990.99±1.72

CarbonOxygenCalciumCopperMagnesiumPhosphorus

COCaCuMgP

Sample A 8.76 32.0 55.69 3.55 0.0 0

Sample B 11.64 53.9 29.73 0.0 1.75 2.98

Sample C 20.6 58.86 18.86 0.0 1.68 0

The existing studies stating that the range of Carbon was from 8.76 to 20.60 %, while Oxygen

showed range from 32.00 to 58.86 %, but calcium that was the most prominent after Oxygen that showed

range within values of 18.86 to 55.69%. Magnesium ranged from 1.68 to 1.75 %, and phosphorus being

lowest illustrated range of 0.0 to 2.98% . This fact was deliberated by studying crab that potassium and

sodium are prominent minerals that were found in crab [9]. Present study was analogous with the study

of Anon [10] and Thirunavukkarasu [11] who found more calcium content in both soft as well as hard

shell of crab. In addition, current study was also in concordance with Hagashi et al. [9]. Findings of this

research was similar to that of Sudhakar et al. [12] who noted that hard portion of crab shell comprise of

majority of minerals as comparison to soft part of shell. It has also been reported that calcium is highly

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abundant in crab shell, while other minerals that were found by them were also resemble with this current

study.

Conclusions

Thus, From the obtained results, the current research pave a way for enthusiastic researchers to

focus on developing new products using crab shells that involves cheaper medicines, toothpastes, bones

strengthening agents as well as beauty products that are demanded by conscious consumers.

Acknowledgements

I expressed my gratitude to Professor Dr. Rehana Yasmeen and Musarrat-Ul-Ain in conducting

the analysis of metals in Labs of department of Zoology of Karachi University. Also special thanks to my

research supervisor, Dr. Zubia Masood for her help and guidance in the preparation of this manuscript.

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